Ensure JNI primitive array type is appropriate.

Check the primitive array type for GetPrimitiveArray, ReleasePrimitiveArray,
GetPrimitiveArrayRegion and SetPrimitiveArrayRegion matches the given array
type. Check the GetPrimitiveArrayCritical and ReleasePrimitiveArrayCritical are
given a primitive array.
Add unit tests that null parameters lead to fatal errors, not crashes. Fix
issues where CheckJNI assumed non-null arguments.
Tidy testing code via the use of nullptr. Add a few extra checks.
Ensure arrays of void are not able to be created, use RI compatible
NoClassDefError.

Bug: 14817823

Change-Id: I9903bcd800d0da1988ced07f61fb97b783c5deab
diff --git a/runtime/jni_internal_test.cc b/runtime/jni_internal_test.cc
index 778b9e5..709530e 100644
--- a/runtime/jni_internal_test.cc
+++ b/runtime/jni_internal_test.cc
@@ -33,35 +33,54 @@
     // Turn on -verbose:jni for the JNI tests.
     // gLogVerbosity.jni = true;
 
-    vm_->AttachCurrentThread(&env_, NULL);
+    vm_->AttachCurrentThread(&env_, nullptr);
 
     ScopedLocalRef<jclass> aioobe(env_,
                                   env_->FindClass("java/lang/ArrayIndexOutOfBoundsException"));
-    CHECK(aioobe.get() != NULL);
+    CHECK(aioobe.get() != nullptr);
     aioobe_ = reinterpret_cast<jclass>(env_->NewGlobalRef(aioobe.get()));
 
     ScopedLocalRef<jclass> ase(env_, env_->FindClass("java/lang/ArrayStoreException"));
-    CHECK(ase.get() != NULL);
+    CHECK(ase.get() != nullptr);
     ase_ = reinterpret_cast<jclass>(env_->NewGlobalRef(ase.get()));
 
     ScopedLocalRef<jclass> sioobe(env_,
                                   env_->FindClass("java/lang/StringIndexOutOfBoundsException"));
-    CHECK(sioobe.get() != NULL);
+    CHECK(sioobe.get() != nullptr);
     sioobe_ = reinterpret_cast<jclass>(env_->NewGlobalRef(sioobe.get()));
   }
 
+  void ExpectException(jclass exception_class) {
+    EXPECT_TRUE(env_->ExceptionCheck());
+    jthrowable exception = env_->ExceptionOccurred();
+    EXPECT_NE(nullptr, exception);
+    env_->ExceptionClear();
+    EXPECT_TRUE(env_->IsInstanceOf(exception, exception_class));
+  }
+
+  void ExpectClassFound(const char* name) {
+    EXPECT_NE(env_->FindClass(name), nullptr) << name;
+    EXPECT_FALSE(env_->ExceptionCheck()) << name;
+  }
+
+  void ExpectClassNotFound(const char* name) {
+    EXPECT_EQ(env_->FindClass(name), nullptr) << name;
+    EXPECT_TRUE(env_->ExceptionCheck()) << name;
+    env_->ExceptionClear();
+  }
+
   void CleanUpJniEnv() {
-    if (aioobe_ != NULL) {
+    if (aioobe_ != nullptr) {
       env_->DeleteGlobalRef(aioobe_);
-      aioobe_ = NULL;
+      aioobe_ = nullptr;
     }
-    if (ase_ != NULL) {
+    if (ase_ != nullptr) {
       env_->DeleteGlobalRef(ase_);
-      ase_ = NULL;
+      ase_ = nullptr;
     }
-    if (sioobe_ != NULL) {
+    if (sioobe_ != nullptr) {
       env_->DeleteGlobalRef(sioobe_);
-      sioobe_ = NULL;
+      sioobe_ = nullptr;
     }
   }
 
@@ -86,9 +105,9 @@
 
 TEST_F(JniInternalTest, AllocObject) {
   jclass c = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
   jobject o = env_->AllocObject(c);
-  ASSERT_TRUE(o != NULL);
+  ASSERT_NE(o, nullptr);
 
   // We have an instance of the class we asked for...
   ASSERT_TRUE(env_->IsInstanceOf(o, c));
@@ -96,139 +115,152 @@
   // we didn't call a constructor.
   ASSERT_EQ(0, env_->GetIntField(o, env_->GetFieldID(c, "count", "I")));
   ASSERT_EQ(0, env_->GetIntField(o, env_->GetFieldID(c, "offset", "I")));
-  ASSERT_TRUE(env_->GetObjectField(o, env_->GetFieldID(c, "value", "[C")) == NULL);
+  ASSERT_TRUE(env_->GetObjectField(o, env_->GetFieldID(c, "value", "[C")) == nullptr);
 }
 
 TEST_F(JniInternalTest, GetVersion) {
   ASSERT_EQ(JNI_VERSION_1_6, env_->GetVersion());
 }
 
-#define EXPECT_CLASS_FOUND(NAME) \
-  EXPECT_TRUE(env_->FindClass(NAME) != NULL); \
-  EXPECT_FALSE(env_->ExceptionCheck())
-
-#define EXPECT_CLASS_NOT_FOUND(NAME) \
-  EXPECT_TRUE(env_->FindClass(NAME) == NULL); \
-  EXPECT_TRUE(env_->ExceptionCheck()); \
-  env_->ExceptionClear()
-
 TEST_F(JniInternalTest, FindClass) {
   // Reference types...
-  EXPECT_CLASS_FOUND("java/lang/String");
+  ExpectClassFound("java/lang/String");
   // ...for arrays too, where you must include "L;".
-  EXPECT_CLASS_FOUND("[Ljava/lang/String;");
+  ExpectClassFound("[Ljava/lang/String;");
   // Primitive arrays are okay too, if the primitive type is valid.
-  EXPECT_CLASS_FOUND("[C");
+  ExpectClassFound("[C");
 
   {
-    // We support . as well as / for compatibility, if -Xcheck:jni is off.
     CheckJniAbortCatcher check_jni_abort_catcher;
-    EXPECT_CLASS_FOUND("java.lang.String");
+    env_->FindClass(nullptr);
+    check_jni_abort_catcher.Check("name == null");
+
+    // We support . as well as / for compatibility, if -Xcheck:jni is off.
+    ExpectClassFound("java.lang.String");
     check_jni_abort_catcher.Check("illegal class name 'java.lang.String'");
-    EXPECT_CLASS_NOT_FOUND("Ljava.lang.String;");
+    ExpectClassNotFound("Ljava.lang.String;");
     check_jni_abort_catcher.Check("illegal class name 'Ljava.lang.String;'");
-    EXPECT_CLASS_FOUND("[Ljava.lang.String;");
+    ExpectClassFound("[Ljava.lang.String;");
     check_jni_abort_catcher.Check("illegal class name '[Ljava.lang.String;'");
-    EXPECT_CLASS_NOT_FOUND("[java.lang.String");
+    ExpectClassNotFound("[java.lang.String");
     check_jni_abort_catcher.Check("illegal class name '[java.lang.String'");
 
     // You can't include the "L;" in a JNI class descriptor.
-    EXPECT_CLASS_NOT_FOUND("Ljava/lang/String;");
+    ExpectClassNotFound("Ljava/lang/String;");
     check_jni_abort_catcher.Check("illegal class name 'Ljava/lang/String;'");
 
     // But you must include it for an array of any reference type.
-    EXPECT_CLASS_NOT_FOUND("[java/lang/String");
+    ExpectClassNotFound("[java/lang/String");
     check_jni_abort_catcher.Check("illegal class name '[java/lang/String'");
 
-    EXPECT_CLASS_NOT_FOUND("[K");
+    ExpectClassNotFound("[K");
     check_jni_abort_catcher.Check("illegal class name '[K'");
+
+    // Void arrays aren't allowed.
+    ExpectClassNotFound("[V");
+    check_jni_abort_catcher.Check("illegal class name '[V'");
   }
 
   // But primitive types aren't allowed...
-  EXPECT_CLASS_NOT_FOUND("C");
-  EXPECT_CLASS_NOT_FOUND("K");
+  ExpectClassNotFound("C");
+  ExpectClassNotFound("V");
+  ExpectClassNotFound("K");
 }
 
-#define EXPECT_EXCEPTION(exception_class) \
-  do { \
-    EXPECT_TRUE(env_->ExceptionCheck()); \
-    jthrowable exception = env_->ExceptionOccurred(); \
-    EXPECT_NE(static_cast<jthrowable>(NULL), exception); \
-    env_->ExceptionClear(); \
-    EXPECT_TRUE(env_->IsInstanceOf(exception, exception_class)); \
-  } while (false)
-
 TEST_F(JniInternalTest, GetFieldID) {
   jclass jlnsfe = env_->FindClass("java/lang/NoSuchFieldError");
-  ASSERT_TRUE(jlnsfe != NULL);
+  ASSERT_NE(jlnsfe, nullptr);
   jclass c = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
 
   // Wrong type.
   jfieldID fid = env_->GetFieldID(c, "count", "J");
-  EXPECT_EQ(static_cast<jfieldID>(NULL), fid);
-  EXPECT_EXCEPTION(jlnsfe);
+  EXPECT_EQ(nullptr, fid);
+  ExpectException(jlnsfe);
 
   // Wrong type where type doesn't exist.
   fid = env_->GetFieldID(c, "count", "Lrod/jane/freddy;");
-  EXPECT_EQ(static_cast<jfieldID>(NULL), fid);
-  EXPECT_EXCEPTION(jlnsfe);
+  EXPECT_EQ(nullptr, fid);
+  ExpectException(jlnsfe);
 
   // Wrong name.
   fid = env_->GetFieldID(c, "Count", "I");
-  EXPECT_EQ(static_cast<jfieldID>(NULL), fid);
-  EXPECT_EXCEPTION(jlnsfe);
+  EXPECT_EQ(nullptr, fid);
+  ExpectException(jlnsfe);
 
   // Good declared field lookup.
   fid = env_->GetFieldID(c, "count", "I");
-  EXPECT_NE(static_cast<jfieldID>(NULL), fid);
-  EXPECT_TRUE(fid != NULL);
+  EXPECT_NE(nullptr, fid);
   EXPECT_FALSE(env_->ExceptionCheck());
 
   // Good superclass field lookup.
   c = env_->FindClass("java/lang/StringBuilder");
   fid = env_->GetFieldID(c, "count", "I");
-  EXPECT_NE(static_cast<jfieldID>(NULL), fid);
-  EXPECT_TRUE(fid != NULL);
+  EXPECT_NE(nullptr, fid);
+  EXPECT_NE(fid, nullptr);
   EXPECT_FALSE(env_->ExceptionCheck());
 
   // Not instance.
   fid = env_->GetFieldID(c, "CASE_INSENSITIVE_ORDER", "Ljava/util/Comparator;");
-  EXPECT_EQ(static_cast<jfieldID>(NULL), fid);
-  EXPECT_EXCEPTION(jlnsfe);
+  EXPECT_EQ(nullptr, fid);
+  ExpectException(jlnsfe);
+
+  // Bad arguments.
+  CheckJniAbortCatcher check_jni_abort_catcher;
+  fid = env_->GetFieldID(nullptr, "count", "I");
+  EXPECT_EQ(nullptr, fid);
+  check_jni_abort_catcher.Check("java_class == null");
+  fid = env_->GetFieldID(c, nullptr, "I");
+  EXPECT_EQ(nullptr, fid);
+  check_jni_abort_catcher.Check("name == null");
+  fid = env_->GetFieldID(c, "count", nullptr);
+  EXPECT_EQ(nullptr, fid);
+  check_jni_abort_catcher.Check("sig == null");
 }
 
 TEST_F(JniInternalTest, GetStaticFieldID) {
   jclass jlnsfe = env_->FindClass("java/lang/NoSuchFieldError");
-  ASSERT_TRUE(jlnsfe != NULL);
+  ASSERT_NE(jlnsfe, nullptr);
   jclass c = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
 
   // Wrong type.
   jfieldID fid = env_->GetStaticFieldID(c, "CASE_INSENSITIVE_ORDER", "J");
-  EXPECT_EQ(static_cast<jfieldID>(NULL), fid);
-  EXPECT_EXCEPTION(jlnsfe);
+  EXPECT_EQ(nullptr, fid);
+  ExpectException(jlnsfe);
 
   // Wrong type where type doesn't exist.
   fid = env_->GetStaticFieldID(c, "CASE_INSENSITIVE_ORDER", "Lrod/jane/freddy;");
-  EXPECT_EQ(static_cast<jfieldID>(NULL), fid);
-  EXPECT_EXCEPTION(jlnsfe);
+  EXPECT_EQ(nullptr, fid);
+  ExpectException(jlnsfe);
 
   // Wrong name.
   fid = env_->GetStaticFieldID(c, "cASE_INSENSITIVE_ORDER", "Ljava/util/Comparator;");
-  EXPECT_EQ(static_cast<jfieldID>(NULL), fid);
-  EXPECT_EXCEPTION(jlnsfe);
+  EXPECT_EQ(nullptr, fid);
+  ExpectException(jlnsfe);
 
   // Good declared field lookup.
   fid = env_->GetStaticFieldID(c, "CASE_INSENSITIVE_ORDER", "Ljava/util/Comparator;");
-  EXPECT_NE(static_cast<jfieldID>(NULL), fid);
-  EXPECT_TRUE(fid != NULL);
+  EXPECT_NE(nullptr, fid);
+  EXPECT_NE(fid, nullptr);
   EXPECT_FALSE(env_->ExceptionCheck());
 
   // Not static.
   fid = env_->GetStaticFieldID(c, "count", "I");
-  EXPECT_EQ(static_cast<jfieldID>(NULL), fid);
-  EXPECT_EXCEPTION(jlnsfe);
+  EXPECT_EQ(nullptr, fid);
+  ExpectException(jlnsfe);
+
+  // Bad arguments.
+  CheckJniAbortCatcher check_jni_abort_catcher;
+  fid = env_->GetStaticFieldID(nullptr, "CASE_INSENSITIVE_ORDER", "Ljava/util/Comparator;");
+  EXPECT_EQ(nullptr, fid);
+  check_jni_abort_catcher.Check("java_class == null");
+  fid = env_->GetStaticFieldID(c, nullptr, "Ljava/util/Comparator;");
+  EXPECT_EQ(nullptr, fid);
+  check_jni_abort_catcher.Check("name == null");
+  fid = env_->GetStaticFieldID(c, "CASE_INSENSITIVE_ORDER", nullptr);
+  EXPECT_EQ(nullptr, fid);
+  check_jni_abort_catcher.Check("sig == null");
 }
 
 TEST_F(JniInternalTest, GetMethodID) {
@@ -242,24 +274,36 @@
   // Check that java.lang.Object.foo() doesn't exist and NoSuchMethodError is
   // a pending exception
   jmethodID method = env_->GetMethodID(jlobject, "foo", "()V");
-  EXPECT_EQ(static_cast<jmethodID>(NULL), method);
-  EXPECT_EXCEPTION(jlnsme);
+  EXPECT_EQ(nullptr, method);
+  ExpectException(jlnsme);
 
   // Check that java.lang.Object.equals() does exist
   method = env_->GetMethodID(jlobject, "equals", "(Ljava/lang/Object;)Z");
-  EXPECT_NE(static_cast<jmethodID>(NULL), method);
+  EXPECT_NE(nullptr, method);
   EXPECT_FALSE(env_->ExceptionCheck());
 
   // Check that GetMethodID for java.lang.String.valueOf(int) fails as the
   // method is static
   method = env_->GetMethodID(jlstring, "valueOf", "(I)Ljava/lang/String;");
-  EXPECT_EQ(static_cast<jmethodID>(NULL), method);
-  EXPECT_EXCEPTION(jlnsme);
+  EXPECT_EQ(nullptr, method);
+  ExpectException(jlnsme);
 
   // Check that GetMethodID for java.lang.NoSuchMethodError.<init>(String) finds the constructor
   method = env_->GetMethodID(jlnsme, "<init>", "(Ljava/lang/String;)V");
-  EXPECT_NE(static_cast<jmethodID>(NULL), method);
+  EXPECT_NE(nullptr, method);
   EXPECT_FALSE(env_->ExceptionCheck());
+
+  // Bad arguments.
+  CheckJniAbortCatcher check_jni_abort_catcher;
+  method = env_->GetMethodID(nullptr, "<init>", "(Ljava/lang/String;)V");
+  EXPECT_EQ(nullptr, method);
+  check_jni_abort_catcher.Check("java_class == null");
+  method = env_->GetMethodID(jlnsme, nullptr, "(Ljava/lang/String;)V");
+  EXPECT_EQ(nullptr, method);
+  check_jni_abort_catcher.Check("name == null");
+  method = env_->GetMethodID(jlnsme, "<init>", nullptr);
+  EXPECT_EQ(nullptr, method);
+  check_jni_abort_catcher.Check("sig == null");
 }
 
 TEST_F(JniInternalTest, GetStaticMethodID) {
@@ -272,93 +316,155 @@
   // Check that java.lang.Object.foo() doesn't exist and NoSuchMethodError is
   // a pending exception
   jmethodID method = env_->GetStaticMethodID(jlobject, "foo", "()V");
-  EXPECT_EQ(static_cast<jmethodID>(NULL), method);
-  EXPECT_EXCEPTION(jlnsme);
+  EXPECT_EQ(nullptr, method);
+  ExpectException(jlnsme);
 
   // Check that GetStaticMethodID for java.lang.Object.equals(Object) fails as
   // the method is not static
   method = env_->GetStaticMethodID(jlobject, "equals", "(Ljava/lang/Object;)Z");
-  EXPECT_EQ(static_cast<jmethodID>(NULL), method);
-  EXPECT_EXCEPTION(jlnsme);
+  EXPECT_EQ(nullptr, method);
+  ExpectException(jlnsme);
 
   // Check that java.lang.String.valueOf(int) does exist
   jclass jlstring = env_->FindClass("java/lang/String");
-  method = env_->GetStaticMethodID(jlstring, "valueOf",
-                                   "(I)Ljava/lang/String;");
-  EXPECT_NE(static_cast<jmethodID>(NULL), method);
+  method = env_->GetStaticMethodID(jlstring, "valueOf", "(I)Ljava/lang/String;");
+  EXPECT_NE(nullptr, method);
   EXPECT_FALSE(env_->ExceptionCheck());
+
+  // Bad arguments.
+  CheckJniAbortCatcher check_jni_abort_catcher;
+  method = env_->GetStaticMethodID(nullptr, "valueOf", "(I)Ljava/lang/String;");
+  EXPECT_EQ(nullptr, method);
+  check_jni_abort_catcher.Check("java_class == null");
+  method = env_->GetStaticMethodID(jlstring, nullptr, "(I)Ljava/lang/String;");
+  EXPECT_EQ(nullptr, method);
+  check_jni_abort_catcher.Check("name == null");
+  method = env_->GetStaticMethodID(jlstring, "valueOf", nullptr);
+  EXPECT_EQ(nullptr, method);
+  check_jni_abort_catcher.Check("sig == null");
 }
 
 TEST_F(JniInternalTest, FromReflectedField_ToReflectedField) {
   jclass jlrField = env_->FindClass("java/lang/reflect/Field");
   jclass c = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
   jfieldID fid = env_->GetFieldID(c, "count", "I");
-  ASSERT_TRUE(fid != NULL);
+  ASSERT_NE(fid, nullptr);
   // Turn the fid into a java.lang.reflect.Field...
   jobject field = env_->ToReflectedField(c, fid, JNI_FALSE);
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
   ASSERT_TRUE(env_->IsInstanceOf(field, jlrField));
   // ...and back again.
   jfieldID fid2 = env_->FromReflectedField(field);
-  ASSERT_TRUE(fid2 != NULL);
+  ASSERT_NE(fid2, nullptr);
   // Make sure we can actually use it.
   jstring s = env_->NewStringUTF("poop");
   ASSERT_EQ(4, env_->GetIntField(s, fid2));
+
+  // Bad arguments.
+  CheckJniAbortCatcher check_jni_abort_catcher;
+  field = env_->ToReflectedField(c, nullptr, JNI_FALSE);
+  EXPECT_EQ(field, nullptr);
+  check_jni_abort_catcher.Check("fid == null");
+  fid2 = env_->FromReflectedField(nullptr);
+  ASSERT_EQ(fid2, nullptr);
+  check_jni_abort_catcher.Check("jlr_field == null");
 }
 
 TEST_F(JniInternalTest, FromReflectedMethod_ToReflectedMethod) {
   jclass jlrMethod = env_->FindClass("java/lang/reflect/Method");
   jclass c = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
   jmethodID mid = env_->GetMethodID(c, "length", "()I");
-  ASSERT_TRUE(mid != NULL);
+  ASSERT_NE(mid, nullptr);
   // Turn the mid into a java.lang.reflect.Method...
   jobject method = env_->ToReflectedMethod(c, mid, JNI_FALSE);
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
   ASSERT_TRUE(env_->IsInstanceOf(method, jlrMethod));
   // ...and back again.
   jmethodID mid2 = env_->FromReflectedMethod(method);
-  ASSERT_TRUE(mid2 != NULL);
+  ASSERT_NE(mid2, nullptr);
   // Make sure we can actually use it.
   jstring s = env_->NewStringUTF("poop");
   ASSERT_EQ(4, env_->CallIntMethod(s, mid2));
+
+  // Bad arguments.
+  CheckJniAbortCatcher check_jni_abort_catcher;
+  method = env_->ToReflectedMethod(c, nullptr, JNI_FALSE);
+  EXPECT_EQ(method, nullptr);
+  check_jni_abort_catcher.Check("mid == null");
+  mid2 = env_->FromReflectedMethod(method);
+  ASSERT_EQ(mid2, nullptr);
+  check_jni_abort_catcher.Check("jlr_method == null");
 }
 
-void BogusMethod() {
-  // You can't pass NULL function pointers to RegisterNatives.
+static void BogusMethod() {
+  // You can't pass nullptr function pointers to RegisterNatives.
 }
 
-TEST_F(JniInternalTest, RegisterNatives) {
+TEST_F(JniInternalTest, RegisterAndUnregisterNatives) {
   jclass jlobject = env_->FindClass("java/lang/Object");
   jclass jlnsme = env_->FindClass("java/lang/NoSuchMethodError");
 
-  // Sanity check that no exceptions are pending
+  // Sanity check that no exceptions are pending.
   ASSERT_FALSE(env_->ExceptionCheck());
 
-  // Check that registering to a non-existent java.lang.Object.foo() causes a
-  // NoSuchMethodError
+  // Check that registering to a non-existent java.lang.Object.foo() causes a NoSuchMethodError.
   {
-    JNINativeMethod methods[] = { { "foo", "()V", NULL } };
-    env_->RegisterNatives(jlobject, methods, 1);
+    JNINativeMethod methods[] = { { "foo", "()V", nullptr } };
+    EXPECT_EQ(env_->RegisterNatives(jlobject, methods, 1), JNI_ERR);
   }
-  EXPECT_EXCEPTION(jlnsme);
+  ExpectException(jlnsme);
 
-  // Check that registering non-native methods causes a NoSuchMethodError
+  // Check that registering non-native methods causes a NoSuchMethodError.
   {
-    JNINativeMethod methods[] = { { "equals", "(Ljava/lang/Object;)Z", NULL } };
-    env_->RegisterNatives(jlobject, methods, 1);
+    JNINativeMethod methods[] = { { "equals", "(Ljava/lang/Object;)Z", nullptr } };
+    EXPECT_EQ(env_->RegisterNatives(jlobject, methods, 1), JNI_ERR);
   }
-  EXPECT_EXCEPTION(jlnsme);
+  ExpectException(jlnsme);
 
-  // Check that registering native methods is successful
+  // Check that registering native methods is successful.
   {
     JNINativeMethod methods[] = { { "notify", "()V", reinterpret_cast<void*>(BogusMethod) } };
-    env_->RegisterNatives(jlobject, methods, 1);
+    EXPECT_EQ(env_->RegisterNatives(jlobject, methods, 1), JNI_OK);
+  }
+  EXPECT_FALSE(env_->ExceptionCheck());
+  EXPECT_EQ(env_->UnregisterNatives(jlobject), JNI_OK);
+
+  // Check that registering no methods isn't a failure.
+  {
+    JNINativeMethod methods[] = { };
+    EXPECT_EQ(env_->RegisterNatives(jlobject, methods, 0), JNI_OK);
+  }
+  EXPECT_FALSE(env_->ExceptionCheck());
+  EXPECT_EQ(env_->UnregisterNatives(jlobject), JNI_OK);
+
+  // Check that registering a -ve number of methods is a failure.
+  CheckJniAbortCatcher check_jni_abort_catcher;
+  for (int i = -10; i < 0; ++i) {
+    JNINativeMethod methods[] = { };
+    EXPECT_EQ(env_->RegisterNatives(jlobject, methods, i), JNI_ERR);
+    check_jni_abort_catcher.Check("negative method count: ");
   }
   EXPECT_FALSE(env_->ExceptionCheck());
 
-  env_->UnregisterNatives(jlobject);
+  // Passing a class of null is a failure.
+  {
+    JNINativeMethod methods[] = { };
+    EXPECT_EQ(env_->RegisterNatives(nullptr, methods, 0), JNI_ERR);
+    check_jni_abort_catcher.Check("java_class == null");
+  }
+
+  // Passing methods as null is a failure.
+  EXPECT_EQ(env_->RegisterNatives(jlobject, nullptr, 1), JNI_ERR);
+  check_jni_abort_catcher.Check("methods == null");
+
+  // Unregisters null is a failure.
+  EXPECT_EQ(env_->UnregisterNatives(nullptr), JNI_ERR);
+  check_jni_abort_catcher.Check("java_class == null");
+
+  // Unregistering a class with no natives is a warning.
+  EXPECT_EQ(env_->UnregisterNatives(jlnsme), JNI_OK);
 }
 
 #define EXPECT_PRIMITIVE_ARRAY(new_fn, \
@@ -368,52 +474,69 @@
                                release_elements_fn, \
                                scalar_type, \
                                expected_class_descriptor) \
+  jsize size = 4; \
+  \
   { \
     CheckJniAbortCatcher jni_abort_catcher; \
     /* Allocate an negative sized array and check it has the right failure type. */ \
-    env_->new_fn(-1); \
+    EXPECT_EQ(env_->new_fn(-1), nullptr); \
     jni_abort_catcher.Check("negative array length: -1"); \
-    env_->new_fn(std::numeric_limits<jint>::min()); \
+    EXPECT_EQ(env_->new_fn(std::numeric_limits<jint>::min()), nullptr); \
     jni_abort_catcher.Check("negative array length: -2147483648"); \
+    /* Pass the array as null. */ \
+    EXPECT_EQ(0, env_->GetArrayLength(nullptr)); \
+    jni_abort_catcher.Check("java_array == null"); \
+    env_->get_region_fn(nullptr, 0, 0, nullptr); \
+    jni_abort_catcher.Check("java_array == null"); \
+    env_->set_region_fn(nullptr, 0, 0, nullptr); \
+    jni_abort_catcher.Check("java_array == null"); \
+    env_->get_elements_fn(nullptr, nullptr); \
+    jni_abort_catcher.Check("java_array == null"); \
+    env_->release_elements_fn(nullptr, nullptr, 0); \
+    jni_abort_catcher.Check("java_array == null"); \
+    /* Pass the elements for region as null. */ \
+    scalar_type ## Array a = env_->new_fn(size); \
+    env_->get_region_fn(a, 0, size, nullptr); \
+    jni_abort_catcher.Check("buf == null"); \
+    env_->set_region_fn(a, 0, size, nullptr); \
+    jni_abort_catcher.Check("buf == null"); \
   } \
-  jsize size = 4; \
-  \
   /* Allocate an array and check it has the right type and length. */ \
   scalar_type ## Array a = env_->new_fn(size); \
-  EXPECT_TRUE(a != NULL); \
+  EXPECT_NE(a, nullptr); \
   EXPECT_TRUE(env_->IsInstanceOf(a, env_->FindClass(expected_class_descriptor))); \
   EXPECT_EQ(size, env_->GetArrayLength(a)); \
   \
   /* GetPrimitiveArrayRegion/SetPrimitiveArrayRegion */ \
   /* AIOOBE for negative start offset. */ \
-  env_->get_region_fn(a, -1, 1, NULL); \
-  EXPECT_EXCEPTION(aioobe_); \
-  env_->set_region_fn(a, -1, 1, NULL); \
-  EXPECT_EXCEPTION(aioobe_); \
+  env_->get_region_fn(a, -1, 1, nullptr); \
+  ExpectException(aioobe_); \
+  env_->set_region_fn(a, -1, 1, nullptr); \
+  ExpectException(aioobe_); \
   \
   /* AIOOBE for negative length. */ \
-  env_->get_region_fn(a, 0, -1, NULL); \
-  EXPECT_EXCEPTION(aioobe_); \
-  env_->set_region_fn(a, 0, -1, NULL); \
-  EXPECT_EXCEPTION(aioobe_); \
+  env_->get_region_fn(a, 0, -1, nullptr); \
+  ExpectException(aioobe_); \
+  env_->set_region_fn(a, 0, -1, nullptr); \
+  ExpectException(aioobe_); \
   \
   /* AIOOBE for buffer overrun. */ \
-  env_->get_region_fn(a, size - 1, size, NULL); \
-  EXPECT_EXCEPTION(aioobe_); \
-  env_->set_region_fn(a, size - 1, size, NULL); \
-  EXPECT_EXCEPTION(aioobe_); \
+  env_->get_region_fn(a, size - 1, size, nullptr); \
+  ExpectException(aioobe_); \
+  env_->set_region_fn(a, size - 1, size, nullptr); \
+  ExpectException(aioobe_); \
   \
-  /* It's okay for the buffer to be NULL as long as the length is 0. */ \
-  env_->get_region_fn(a, 2, 0, NULL); \
+  /* It's okay for the buffer to be nullptr as long as the length is 0. */ \
+  env_->get_region_fn(a, 2, 0, nullptr); \
   /* Even if the offset is invalid... */ \
-  env_->get_region_fn(a, 123, 0, NULL); \
-  EXPECT_EXCEPTION(aioobe_); \
+  env_->get_region_fn(a, 123, 0, nullptr); \
+  ExpectException(aioobe_); \
   \
-  /* It's okay for the buffer to be NULL as long as the length is 0. */ \
-  env_->set_region_fn(a, 2, 0, NULL); \
+  /* It's okay for the buffer to be nullptr as long as the length is 0. */ \
+  env_->set_region_fn(a, 2, 0, nullptr); \
   /* Even if the offset is invalid... */ \
-  env_->set_region_fn(a, 123, 0, NULL); \
-  EXPECT_EXCEPTION(aioobe_); \
+  env_->set_region_fn(a, 123, 0, nullptr); \
+  ExpectException(aioobe_); \
   \
   /* Prepare a couple of buffers. */ \
   UniquePtr<scalar_type[]> src_buf(new scalar_type[size]); \
@@ -437,12 +560,12 @@
   EXPECT_EQ(memcmp(&src_buf[0], &dst_buf[0], size * sizeof(scalar_type)), 0) \
     << "full copy not equal"; \
   /* GetPrimitiveArrayCritical */ \
-  void* v = env_->GetPrimitiveArrayCritical(a, NULL); \
+  void* v = env_->GetPrimitiveArrayCritical(a, nullptr); \
   EXPECT_EQ(memcmp(&src_buf[0], v, size * sizeof(scalar_type)), 0) \
     << "GetPrimitiveArrayCritical not equal"; \
   env_->ReleasePrimitiveArrayCritical(a, v, 0); \
   /* GetXArrayElements */ \
-  scalar_type* xs = env_->get_elements_fn(a, NULL); \
+  scalar_type* xs = env_->get_elements_fn(a, nullptr); \
   EXPECT_EQ(memcmp(&src_buf[0], xs, size * sizeof(scalar_type)), 0) \
     << # get_elements_fn " not equal"; \
   env_->release_elements_fn(a, xs, 0); \
@@ -480,31 +603,206 @@
                          GetShortArrayElements, ReleaseShortArrayElements, jshort, "[S");
 }
 
+TEST_F(JniInternalTest, GetPrimitiveArrayElementsOfWrongType) {
+  CheckJniAbortCatcher jni_abort_catcher;
+  jbooleanArray array = env_->NewBooleanArray(10);
+  jboolean is_copy;
+  EXPECT_EQ(env_->GetByteArrayElements(reinterpret_cast<jbyteArray>(array), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get byte primitive array elements with an object of type boolean[]");
+  EXPECT_EQ(env_->GetShortArrayElements(reinterpret_cast<jshortArray>(array), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get short primitive array elements with an object of type boolean[]");
+  EXPECT_EQ(env_->GetCharArrayElements(reinterpret_cast<jcharArray>(array), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get char primitive array elements with an object of type boolean[]");
+  EXPECT_EQ(env_->GetIntArrayElements(reinterpret_cast<jintArray>(array), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get int primitive array elements with an object of type boolean[]");
+  EXPECT_EQ(env_->GetLongArrayElements(reinterpret_cast<jlongArray>(array), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get long primitive array elements with an object of type boolean[]");
+  EXPECT_EQ(env_->GetFloatArrayElements(reinterpret_cast<jfloatArray>(array), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get float primitive array elements with an object of type boolean[]");
+  EXPECT_EQ(env_->GetDoubleArrayElements(reinterpret_cast<jdoubleArray>(array), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get double primitive array elements with an object of type boolean[]");
+  jbyteArray array2 = env_->NewByteArray(10);
+  EXPECT_EQ(env_->GetBooleanArrayElements(reinterpret_cast<jbooleanArray>(array2), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get boolean primitive array elements with an object of type byte[]");
+  jobject object = env_->NewStringUTF("Test String");
+  EXPECT_EQ(env_->GetBooleanArrayElements(reinterpret_cast<jbooleanArray>(object), &is_copy), nullptr);
+  jni_abort_catcher.Check(
+      "attempt to get boolean primitive array elements with an object of type java.lang.String");
+}
+
+TEST_F(JniInternalTest, ReleasePrimitiveArrayElementsOfWrongType) {
+  CheckJniAbortCatcher jni_abort_catcher;
+  jbooleanArray array = env_->NewBooleanArray(10);
+  ASSERT_TRUE(array != nullptr);
+  jboolean is_copy;
+  jboolean* elements = env_->GetBooleanArrayElements(array, &is_copy);
+  ASSERT_TRUE(elements != nullptr);
+  env_->ReleaseByteArrayElements(reinterpret_cast<jbyteArray>(array),
+                                 reinterpret_cast<jbyte*>(elements), 0);
+  jni_abort_catcher.Check(
+      "attempt to release byte primitive array elements with an object of type boolean[]");
+  env_->ReleaseShortArrayElements(reinterpret_cast<jshortArray>(array),
+                                  reinterpret_cast<jshort*>(elements), 0);
+  jni_abort_catcher.Check(
+      "attempt to release short primitive array elements with an object of type boolean[]");
+  env_->ReleaseCharArrayElements(reinterpret_cast<jcharArray>(array),
+                                 reinterpret_cast<jchar*>(elements), 0);
+  jni_abort_catcher.Check(
+      "attempt to release char primitive array elements with an object of type boolean[]");
+  env_->ReleaseIntArrayElements(reinterpret_cast<jintArray>(array),
+                                reinterpret_cast<jint*>(elements), 0);
+  jni_abort_catcher.Check(
+      "attempt to release int primitive array elements with an object of type boolean[]");
+  env_->ReleaseLongArrayElements(reinterpret_cast<jlongArray>(array),
+                                 reinterpret_cast<jlong*>(elements), 0);
+  jni_abort_catcher.Check(
+      "attempt to release long primitive array elements with an object of type boolean[]");
+  env_->ReleaseFloatArrayElements(reinterpret_cast<jfloatArray>(array),
+                                  reinterpret_cast<jfloat*>(elements), 0);
+  jni_abort_catcher.Check(
+      "attempt to release float primitive array elements with an object of type boolean[]");
+  env_->ReleaseDoubleArrayElements(reinterpret_cast<jdoubleArray>(array),
+                                  reinterpret_cast<jdouble*>(elements), 0);
+  jni_abort_catcher.Check(
+      "attempt to release double primitive array elements with an object of type boolean[]");
+  jbyteArray array2 = env_->NewByteArray(10);
+  env_->ReleaseBooleanArrayElements(reinterpret_cast<jbooleanArray>(array2), elements, 0);
+  jni_abort_catcher.Check(
+      "attempt to release boolean primitive array elements with an object of type byte[]");
+  jobject object = env_->NewStringUTF("Test String");
+  env_->ReleaseBooleanArrayElements(reinterpret_cast<jbooleanArray>(object), elements, 0);
+  jni_abort_catcher.Check(
+      "attempt to release boolean primitive array elements with an object of type java.lang.String");
+}
+TEST_F(JniInternalTest, GetReleasePrimitiveArrayCriticalOfWrongType) {
+  CheckJniAbortCatcher jni_abort_catcher;
+  jobject object = env_->NewStringUTF("Test String");
+  jboolean is_copy;
+  void* elements = env_->GetPrimitiveArrayCritical(reinterpret_cast<jarray>(object), &is_copy);
+  jni_abort_catcher.Check("expected primitive array, given java.lang.String");
+  env_->ReleasePrimitiveArrayCritical(reinterpret_cast<jarray>(object), elements, 0);
+  jni_abort_catcher.Check("expected primitive array, given java.lang.String");
+}
+
+TEST_F(JniInternalTest, GetPrimitiveArrayRegionElementsOfWrongType) {
+  CheckJniAbortCatcher jni_abort_catcher;
+  constexpr size_t kLength = 10;
+  jbooleanArray array = env_->NewBooleanArray(kLength);
+  ASSERT_TRUE(array != nullptr);
+  jboolean elements[kLength];
+  env_->GetByteArrayRegion(reinterpret_cast<jbyteArray>(array), 0, kLength,
+                           reinterpret_cast<jbyte*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of byte primitive array elements with an object of type boolean[]");
+  env_->GetShortArrayRegion(reinterpret_cast<jshortArray>(array), 0, kLength,
+                            reinterpret_cast<jshort*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of short primitive array elements with an object of type boolean[]");
+  env_->GetCharArrayRegion(reinterpret_cast<jcharArray>(array), 0, kLength,
+                           reinterpret_cast<jchar*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of char primitive array elements with an object of type boolean[]");
+  env_->GetIntArrayRegion(reinterpret_cast<jintArray>(array), 0, kLength,
+                          reinterpret_cast<jint*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of int primitive array elements with an object of type boolean[]");
+  env_->GetLongArrayRegion(reinterpret_cast<jlongArray>(array), 0, kLength,
+                           reinterpret_cast<jlong*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of long primitive array elements with an object of type boolean[]");
+  env_->GetFloatArrayRegion(reinterpret_cast<jfloatArray>(array), 0, kLength,
+                            reinterpret_cast<jfloat*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of float primitive array elements with an object of type boolean[]");
+  env_->GetDoubleArrayRegion(reinterpret_cast<jdoubleArray>(array), 0, kLength,
+                           reinterpret_cast<jdouble*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of double primitive array elements with an object of type boolean[]");
+  jbyteArray array2 = env_->NewByteArray(10);
+  env_->GetBooleanArrayRegion(reinterpret_cast<jbooleanArray>(array2), 0, kLength,
+                              reinterpret_cast<jboolean*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of boolean primitive array elements with an object of type byte[]");
+  jobject object = env_->NewStringUTF("Test String");
+  env_->GetBooleanArrayRegion(reinterpret_cast<jbooleanArray>(object), 0, kLength,
+                              reinterpret_cast<jboolean*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to get region of boolean primitive array elements with an object of type java.lang.String");
+}
+
+TEST_F(JniInternalTest, SetPrimitiveArrayRegionElementsOfWrongType) {
+  CheckJniAbortCatcher jni_abort_catcher;
+  constexpr size_t kLength = 10;
+  jbooleanArray array = env_->NewBooleanArray(kLength);
+  ASSERT_TRUE(array != nullptr);
+  jboolean elements[kLength];
+  env_->SetByteArrayRegion(reinterpret_cast<jbyteArray>(array), 0, kLength,
+                           reinterpret_cast<jbyte*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of byte primitive array elements with an object of type boolean[]");
+  env_->SetShortArrayRegion(reinterpret_cast<jshortArray>(array), 0, kLength,
+                            reinterpret_cast<jshort*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of short primitive array elements with an object of type boolean[]");
+  env_->SetCharArrayRegion(reinterpret_cast<jcharArray>(array), 0, kLength,
+                           reinterpret_cast<jchar*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of char primitive array elements with an object of type boolean[]");
+  env_->SetIntArrayRegion(reinterpret_cast<jintArray>(array), 0, kLength,
+                          reinterpret_cast<jint*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of int primitive array elements with an object of type boolean[]");
+  env_->SetLongArrayRegion(reinterpret_cast<jlongArray>(array), 0, kLength,
+                           reinterpret_cast<jlong*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of long primitive array elements with an object of type boolean[]");
+  env_->SetFloatArrayRegion(reinterpret_cast<jfloatArray>(array), 0, kLength,
+                            reinterpret_cast<jfloat*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of float primitive array elements with an object of type boolean[]");
+  env_->SetDoubleArrayRegion(reinterpret_cast<jdoubleArray>(array), 0, kLength,
+                           reinterpret_cast<jdouble*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of double primitive array elements with an object of type boolean[]");
+  jbyteArray array2 = env_->NewByteArray(10);
+  env_->SetBooleanArrayRegion(reinterpret_cast<jbooleanArray>(array2), 0, kLength,
+                              reinterpret_cast<jboolean*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of boolean primitive array elements with an object of type byte[]");
+  jobject object = env_->NewStringUTF("Test String");
+  env_->SetBooleanArrayRegion(reinterpret_cast<jbooleanArray>(object), 0, kLength,
+                              reinterpret_cast<jboolean*>(elements));
+  jni_abort_catcher.Check(
+      "attempt to set region of boolean primitive array elements with an object of type java.lang.String");
+}
+
 TEST_F(JniInternalTest, NewObjectArray) {
   jclass element_class = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(element_class != nullptr);
+  ASSERT_NE(element_class, nullptr);
   jclass array_class = env_->FindClass("[Ljava/lang/String;");
-  ASSERT_TRUE(array_class != nullptr);
+  ASSERT_NE(array_class, nullptr);
 
   jobjectArray a = env_->NewObjectArray(0, element_class, nullptr);
-  EXPECT_TRUE(a != nullptr);
+  EXPECT_NE(a, nullptr);
   EXPECT_TRUE(env_->IsInstanceOf(a, array_class));
   EXPECT_EQ(0, env_->GetArrayLength(a));
 
   a = env_->NewObjectArray(1, element_class, nullptr);
-  EXPECT_TRUE(a != nullptr);
+  EXPECT_NE(a, nullptr);
   EXPECT_TRUE(env_->IsInstanceOf(a, array_class));
   EXPECT_EQ(1, env_->GetArrayLength(a));
   EXPECT_TRUE(env_->IsSameObject(env_->GetObjectArrayElement(a, 0), nullptr));
-}
 
-TEST_F(JniInternalTest, NewObjectArrayWithNegativeLength) {
-  jclass element_class = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(element_class != nullptr);
-  jclass array_class = env_->FindClass("[Ljava/lang/String;");
-  ASSERT_TRUE(array_class != nullptr);
+  // Negative array length checks.
   CheckJniAbortCatcher jni_abort_catcher;
-
   env_->NewObjectArray(-1, element_class, nullptr);
   jni_abort_catcher.Check("negative array length: -1");
 
@@ -521,6 +819,8 @@
 
   CheckJniAbortCatcher jni_abort_catcher;
   for (size_t i = 0; i < strlen(primitive_descriptors); ++i) {
+    env_->NewObjectArray(0, nullptr, nullptr);
+    jni_abort_catcher.Check("element_jclass == null");
     jclass primitive_class = GetPrimitiveClass(primitive_descriptors[i]);
     env_->NewObjectArray(1, primitive_class, nullptr);
     std::string error_msg(StringPrintf("not an object type: %s", primitive_names[i]));
@@ -530,13 +830,13 @@
 
 TEST_F(JniInternalTest, NewObjectArrayWithInitialValue) {
   jclass element_class = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(element_class != nullptr);
+  ASSERT_NE(element_class, nullptr);
   jclass array_class = env_->FindClass("[Ljava/lang/String;");
-  ASSERT_TRUE(array_class != nullptr);
+  ASSERT_NE(array_class, nullptr);
 
   jstring s = env_->NewStringUTF("poop");
   jobjectArray a = env_->NewObjectArray(2, element_class, s);
-  EXPECT_TRUE(a != nullptr);
+  EXPECT_NE(a, nullptr);
   EXPECT_TRUE(env_->IsInstanceOf(a, array_class));
   EXPECT_EQ(2, env_->GetArrayLength(a));
   EXPECT_TRUE(env_->IsSameObject(env_->GetObjectArrayElement(a, 0), s));
@@ -555,9 +855,9 @@
 
 TEST_F(JniInternalTest, GetObjectClass) {
   jclass string_class = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(string_class != NULL);
+  ASSERT_NE(string_class, nullptr);
   jclass class_class = env_->FindClass("java/lang/Class");
-  ASSERT_TRUE(class_class != NULL);
+  ASSERT_NE(class_class, nullptr);
 
   jstring s = env_->NewStringUTF("poop");
   jclass c = env_->GetObjectClass(s);
@@ -565,33 +865,50 @@
 
   jclass c2 = env_->GetObjectClass(c);
   ASSERT_TRUE(env_->IsSameObject(class_class, env_->GetObjectClass(c2)));
+
+  // Null as object should fail.
+  CheckJniAbortCatcher jni_abort_catcher;
+  EXPECT_EQ(env_->GetObjectClass(nullptr), nullptr);
+  jni_abort_catcher.Check("java_object == null");
 }
 
 TEST_F(JniInternalTest, GetSuperclass) {
   jclass object_class = env_->FindClass("java/lang/Object");
-  ASSERT_TRUE(object_class != NULL);
+  ASSERT_NE(object_class, nullptr);
   jclass string_class = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(string_class != NULL);
+  ASSERT_NE(string_class, nullptr);
   jclass runnable_interface = env_->FindClass("java/lang/Runnable");
-  ASSERT_TRUE(runnable_interface != NULL);
+  ASSERT_NE(runnable_interface, nullptr);
   ASSERT_TRUE(env_->IsSameObject(object_class, env_->GetSuperclass(string_class)));
-  ASSERT_TRUE(env_->GetSuperclass(object_class) == NULL);
+  ASSERT_EQ(env_->GetSuperclass(object_class), nullptr);
   ASSERT_TRUE(env_->IsSameObject(object_class, env_->GetSuperclass(runnable_interface)));
+
+  // Null as class should fail.
+  CheckJniAbortCatcher jni_abort_catcher;
+  EXPECT_EQ(env_->GetSuperclass(nullptr), nullptr);
+  jni_abort_catcher.Check("java_class == null");
 }
 
 TEST_F(JniInternalTest, IsAssignableFrom) {
   jclass object_class = env_->FindClass("java/lang/Object");
-  ASSERT_TRUE(object_class != NULL);
+  ASSERT_NE(object_class, nullptr);
   jclass string_class = env_->FindClass("java/lang/String");
-  ASSERT_TRUE(string_class != NULL);
+  ASSERT_NE(string_class, nullptr);
 
   ASSERT_TRUE(env_->IsAssignableFrom(object_class, string_class));
   ASSERT_FALSE(env_->IsAssignableFrom(string_class, object_class));
+
+  // Null as either class should fail.
+  CheckJniAbortCatcher jni_abort_catcher;
+  EXPECT_EQ(env_->IsAssignableFrom(nullptr, string_class), JNI_FALSE);
+  jni_abort_catcher.Check("java_class1 == null");
+  EXPECT_EQ(env_->IsAssignableFrom(object_class, nullptr), JNI_FALSE);
+  jni_abort_catcher.Check("java_class2 == null");
 }
 
 TEST_F(JniInternalTest, GetObjectRefType) {
   jclass local = env_->FindClass("java/lang/Object");
-  ASSERT_TRUE(local != NULL);
+  ASSERT_TRUE(local != nullptr);
   EXPECT_EQ(JNILocalRefType, env_->GetObjectRefType(local));
 
   jobject global = env_->NewGlobalRef(local);
@@ -604,33 +921,38 @@
   EXPECT_EQ(JNIInvalidRefType, env_->GetObjectRefType(invalid));
 
   // TODO: invoke a native method and test that its arguments are considered local references.
+
+  // Null as object should fail.
+  CheckJniAbortCatcher jni_abort_catcher;
+  EXPECT_EQ(JNIInvalidRefType, env_->GetObjectRefType(nullptr));
+  jni_abort_catcher.Check("java_object == null");
 }
 
 TEST_F(JniInternalTest, StaleWeakGlobal) {
   jclass java_lang_Class = env_->FindClass("java/lang/Class");
-  ASSERT_TRUE(java_lang_Class != NULL);
-  jobjectArray local_ref = env_->NewObjectArray(1, java_lang_Class, NULL);
-  ASSERT_TRUE(local_ref != NULL);
+  ASSERT_NE(java_lang_Class, nullptr);
+  jobjectArray local_ref = env_->NewObjectArray(1, java_lang_Class, nullptr);
+  ASSERT_NE(local_ref, nullptr);
   jweak weak_global = env_->NewWeakGlobalRef(local_ref);
-  ASSERT_TRUE(weak_global != NULL);
+  ASSERT_NE(weak_global, nullptr);
   env_->DeleteLocalRef(local_ref);
   Runtime::Current()->GetHeap()->CollectGarbage(false);  // GC should clear the weak global.
   jobject new_global_ref = env_->NewGlobalRef(weak_global);
-  EXPECT_TRUE(new_global_ref == NULL);
+  EXPECT_EQ(new_global_ref, nullptr);
   jobject new_local_ref = env_->NewLocalRef(weak_global);
-  EXPECT_TRUE(new_local_ref == NULL);
+  EXPECT_EQ(new_local_ref, nullptr);
 }
 
 TEST_F(JniInternalTest, NewStringUTF) {
-  EXPECT_TRUE(env_->NewStringUTF(NULL) == NULL);
+  EXPECT_EQ(env_->NewStringUTF(nullptr), nullptr);
   jstring s;
 
   s = env_->NewStringUTF("");
-  EXPECT_TRUE(s != NULL);
+  EXPECT_NE(s, nullptr);
   EXPECT_EQ(0, env_->GetStringLength(s));
   EXPECT_EQ(0, env_->GetStringUTFLength(s));
   s = env_->NewStringUTF("hello");
-  EXPECT_TRUE(s != NULL);
+  EXPECT_NE(s, nullptr);
   EXPECT_EQ(5, env_->GetStringLength(s));
   EXPECT_EQ(5, env_->GetStringUTFLength(s));
 
@@ -641,11 +963,11 @@
   jchar chars[] = { 'h', 'i' };
   jstring s;
   s = env_->NewString(chars, 0);
-  EXPECT_TRUE(s != NULL);
+  EXPECT_NE(s, nullptr);
   EXPECT_EQ(0, env_->GetStringLength(s));
   EXPECT_EQ(0, env_->GetStringUTFLength(s));
   s = env_->NewString(chars, 2);
-  EXPECT_TRUE(s != NULL);
+  EXPECT_NE(s, nullptr);
   EXPECT_EQ(2, env_->GetStringLength(s));
   EXPECT_EQ(2, env_->GetStringUTFLength(s));
 
@@ -654,7 +976,7 @@
 
 TEST_F(JniInternalTest, NewStringNullCharsZeroLength) {
   jstring s = env_->NewString(nullptr, 0);
-  EXPECT_TRUE(s != nullptr);
+  EXPECT_NE(s, nullptr);
   EXPECT_EQ(0, env_->GetStringLength(s));
 }
 
@@ -678,16 +1000,16 @@
 
 TEST_F(JniInternalTest, GetStringRegion_GetStringUTFRegion) {
   jstring s = env_->NewStringUTF("hello");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_TRUE(s != nullptr);
 
-  env_->GetStringRegion(s, -1, 0, NULL);
-  EXPECT_EXCEPTION(sioobe_);
-  env_->GetStringRegion(s, 0, -1, NULL);
-  EXPECT_EXCEPTION(sioobe_);
-  env_->GetStringRegion(s, 0, 10, NULL);
-  EXPECT_EXCEPTION(sioobe_);
-  env_->GetStringRegion(s, 10, 1, NULL);
-  EXPECT_EXCEPTION(sioobe_);
+  env_->GetStringRegion(s, -1, 0, nullptr);
+  ExpectException(sioobe_);
+  env_->GetStringRegion(s, 0, -1, nullptr);
+  ExpectException(sioobe_);
+  env_->GetStringRegion(s, 0, 10, nullptr);
+  ExpectException(sioobe_);
+  env_->GetStringRegion(s, 10, 1, nullptr);
+  ExpectException(sioobe_);
 
   jchar chars[4] = { 'x', 'x', 'x', 'x' };
   env_->GetStringRegion(s, 1, 2, &chars[1]);
@@ -696,20 +1018,20 @@
   EXPECT_EQ('l', chars[2]);
   EXPECT_EQ('x', chars[3]);
 
-  // It's okay for the buffer to be NULL as long as the length is 0.
-  env_->GetStringRegion(s, 2, 0, NULL);
+  // It's okay for the buffer to be nullptr as long as the length is 0.
+  env_->GetStringRegion(s, 2, 0, nullptr);
   // Even if the offset is invalid...
-  env_->GetStringRegion(s, 123, 0, NULL);
-  EXPECT_EXCEPTION(sioobe_);
+  env_->GetStringRegion(s, 123, 0, nullptr);
+  ExpectException(sioobe_);
 
-  env_->GetStringUTFRegion(s, -1, 0, NULL);
-  EXPECT_EXCEPTION(sioobe_);
-  env_->GetStringUTFRegion(s, 0, -1, NULL);
-  EXPECT_EXCEPTION(sioobe_);
-  env_->GetStringUTFRegion(s, 0, 10, NULL);
-  EXPECT_EXCEPTION(sioobe_);
-  env_->GetStringUTFRegion(s, 10, 1, NULL);
-  EXPECT_EXCEPTION(sioobe_);
+  env_->GetStringUTFRegion(s, -1, 0, nullptr);
+  ExpectException(sioobe_);
+  env_->GetStringUTFRegion(s, 0, -1, nullptr);
+  ExpectException(sioobe_);
+  env_->GetStringUTFRegion(s, 0, 10, nullptr);
+  ExpectException(sioobe_);
+  env_->GetStringUTFRegion(s, 10, 1, nullptr);
+  ExpectException(sioobe_);
 
   char bytes[4] = { 'x', 'x', 'x', 'x' };
   env_->GetStringUTFRegion(s, 1, 2, &bytes[1]);
@@ -718,25 +1040,25 @@
   EXPECT_EQ('l', bytes[2]);
   EXPECT_EQ('x', bytes[3]);
 
-  // It's okay for the buffer to be NULL as long as the length is 0.
-  env_->GetStringUTFRegion(s, 2, 0, NULL);
+  // It's okay for the buffer to be nullptr as long as the length is 0.
+  env_->GetStringUTFRegion(s, 2, 0, nullptr);
   // Even if the offset is invalid...
-  env_->GetStringUTFRegion(s, 123, 0, NULL);
-  EXPECT_EXCEPTION(sioobe_);
+  env_->GetStringUTFRegion(s, 123, 0, nullptr);
+  ExpectException(sioobe_);
 }
 
 TEST_F(JniInternalTest, GetStringUTFChars_ReleaseStringUTFChars) {
-  // Passing in a NULL jstring is ignored normally, but caught by -Xcheck:jni.
+  // Passing in a nullptr jstring is ignored normally, but caught by -Xcheck:jni.
   {
     CheckJniAbortCatcher check_jni_abort_catcher;
-    EXPECT_TRUE(env_->GetStringUTFChars(NULL, NULL) == NULL);
+    EXPECT_EQ(env_->GetStringUTFChars(nullptr, nullptr), nullptr);
     check_jni_abort_catcher.Check("GetStringUTFChars received null jstring");
   }
 
   jstring s = env_->NewStringUTF("hello");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_TRUE(s != nullptr);
 
-  const char* utf = env_->GetStringUTFChars(s, NULL);
+  const char* utf = env_->GetStringUTFChars(s, nullptr);
   EXPECT_STREQ("hello", utf);
   env_->ReleaseStringUTFChars(s, utf);
 
@@ -749,10 +1071,10 @@
 
 TEST_F(JniInternalTest, GetStringChars_ReleaseStringChars) {
   jstring s = env_->NewStringUTF("hello");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_TRUE(s != nullptr);
 
   jchar expected[] = { 'h', 'e', 'l', 'l', 'o' };
-  const jchar* chars = env_->GetStringChars(s, NULL);
+  const jchar* chars = env_->GetStringChars(s, nullptr);
   EXPECT_EQ(expected[0], chars[0]);
   EXPECT_EQ(expected[1], chars[1]);
   EXPECT_EQ(expected[2], chars[2]);
@@ -773,10 +1095,10 @@
 
 TEST_F(JniInternalTest, GetStringCritical_ReleaseStringCritical) {
   jstring s = env_->NewStringUTF("hello");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_TRUE(s != nullptr);
 
   jchar expected[] = { 'h', 'e', 'l', 'l', 'o' };
-  const jchar* chars = env_->GetStringCritical(s, NULL);
+  const jchar* chars = env_->GetStringCritical(s, nullptr);
   EXPECT_EQ(expected[0], chars[0]);
   EXPECT_EQ(expected[1], chars[1]);
   EXPECT_EQ(expected[2], chars[2]);
@@ -798,45 +1120,72 @@
 
 TEST_F(JniInternalTest, GetObjectArrayElement_SetObjectArrayElement) {
   jclass java_lang_Class = env_->FindClass("java/lang/Class");
-  ASSERT_TRUE(java_lang_Class != NULL);
+  ASSERT_TRUE(java_lang_Class != nullptr);
 
-  jobjectArray array = env_->NewObjectArray(1, java_lang_Class, NULL);
-  EXPECT_TRUE(array != NULL);
-  EXPECT_TRUE(env_->GetObjectArrayElement(array, 0) == NULL);
+  jobjectArray array = env_->NewObjectArray(1, java_lang_Class, nullptr);
+  EXPECT_NE(array, nullptr);
+  EXPECT_EQ(env_->GetObjectArrayElement(array, 0), nullptr);
   env_->SetObjectArrayElement(array, 0, java_lang_Class);
   EXPECT_TRUE(env_->IsSameObject(env_->GetObjectArrayElement(array, 0), java_lang_Class));
 
   // ArrayIndexOutOfBounds for negative index.
   env_->SetObjectArrayElement(array, -1, java_lang_Class);
-  EXPECT_EXCEPTION(aioobe_);
+  ExpectException(aioobe_);
 
   // ArrayIndexOutOfBounds for too-large index.
   env_->SetObjectArrayElement(array, 1, java_lang_Class);
-  EXPECT_EXCEPTION(aioobe_);
+  ExpectException(aioobe_);
 
   // ArrayStoreException thrown for bad types.
   env_->SetObjectArrayElement(array, 0, env_->NewStringUTF("not a jclass!"));
-  EXPECT_EXCEPTION(ase_);
+  ExpectException(ase_);
+
+  // Null as array should fail.
+  CheckJniAbortCatcher jni_abort_catcher;
+  EXPECT_EQ(nullptr, env_->GetObjectArrayElement(nullptr, 0));
+  jni_abort_catcher.Check("java_array == null");
+  env_->SetObjectArrayElement(nullptr, 0, nullptr);
+  jni_abort_catcher.Check("java_array == null");
 }
 
 #define EXPECT_STATIC_PRIMITIVE_FIELD(type, field_name, sig, value1, value2) \
   do { \
     jfieldID fid = env_->GetStaticFieldID(c, field_name, sig); \
-    EXPECT_TRUE(fid != NULL); \
+    EXPECT_NE(fid, nullptr); \
     env_->SetStatic ## type ## Field(c, fid, value1); \
-    EXPECT_TRUE(value1 == env_->GetStatic ## type ## Field(c, fid)); \
+    EXPECT_EQ(value1, env_->GetStatic ## type ## Field(c, fid)); \
     env_->SetStatic ## type ## Field(c, fid, value2); \
-    EXPECT_TRUE(value2 == env_->GetStatic ## type ## Field(c, fid)); \
+    EXPECT_EQ(value2, env_->GetStatic ## type ## Field(c, fid)); \
+    \
+    CheckJniAbortCatcher jni_abort_catcher; \
+    env_->GetStatic ## type ## Field(nullptr, fid); \
+    jni_abort_catcher.Check("received null jclass"); \
+    env_->SetStatic ## type ## Field(nullptr, fid, value1); \
+    jni_abort_catcher.Check("received null jclass"); \
+    env_->GetStatic ## type ## Field(c, nullptr); \
+    jni_abort_catcher.Check("fid == null"); \
+    env_->SetStatic ## type ## Field(c, nullptr, value1); \
+    jni_abort_catcher.Check("fid == null"); \
   } while (false)
 
 #define EXPECT_PRIMITIVE_FIELD(instance, type, field_name, sig, value1, value2) \
   do { \
     jfieldID fid = env_->GetFieldID(c, field_name, sig); \
-    EXPECT_TRUE(fid != NULL); \
+    EXPECT_NE(fid, nullptr); \
     env_->Set ## type ## Field(instance, fid, value1); \
-    EXPECT_TRUE(value1 == env_->Get ## type ## Field(instance, fid)); \
+    EXPECT_EQ(value1, env_->Get ## type ## Field(instance, fid)); \
     env_->Set ## type ## Field(instance, fid, value2); \
-    EXPECT_TRUE(value2 == env_->Get ## type ## Field(instance, fid)); \
+    EXPECT_EQ(value2, env_->Get ## type ## Field(instance, fid)); \
+    \
+    CheckJniAbortCatcher jni_abort_catcher; \
+    env_->Get ## type ## Field(nullptr, fid); \
+    jni_abort_catcher.Check("obj == null"); \
+    env_->Set ## type ## Field(nullptr, fid, value1); \
+    jni_abort_catcher.Check("obj == null"); \
+    env_->Get ## type ## Field(instance, nullptr); \
+    jni_abort_catcher.Check("fid == null"); \
+    env_->Set ## type ## Field(instance, nullptr, value1); \
+    jni_abort_catcher.Check("fid == null"); \
   } while (false)
 
 
@@ -845,14 +1194,14 @@
   Thread::Current()->TransitionFromSuspendedToRunnable();
   LoadDex("AllFields");
   bool started = runtime_->Start();
-  CHECK(started);
+  ASSERT_TRUE(started);
 
   jclass c = env_->FindClass("AllFields");
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
   jobject o = env_->AllocObject(c);
-  ASSERT_TRUE(o != NULL);
+  ASSERT_NE(o, nullptr);
 
-  EXPECT_STATIC_PRIMITIVE_FIELD(Boolean, "sZ", "Z", true, false);
+  EXPECT_STATIC_PRIMITIVE_FIELD(Boolean, "sZ", "Z", JNI_TRUE, JNI_FALSE);
   EXPECT_STATIC_PRIMITIVE_FIELD(Byte, "sB", "B", 1, 2);
   EXPECT_STATIC_PRIMITIVE_FIELD(Char, "sC", "C", 'a', 'b');
   EXPECT_STATIC_PRIMITIVE_FIELD(Double, "sD", "D", 1.0, 2.0);
@@ -861,7 +1210,7 @@
   EXPECT_STATIC_PRIMITIVE_FIELD(Long, "sJ", "J", 1, 2);
   EXPECT_STATIC_PRIMITIVE_FIELD(Short, "sS", "S", 1, 2);
 
-  EXPECT_PRIMITIVE_FIELD(o, Boolean, "iZ", "Z", true, false);
+  EXPECT_PRIMITIVE_FIELD(o, Boolean, "iZ", "Z", JNI_TRUE, JNI_FALSE);
   EXPECT_PRIMITIVE_FIELD(o, Byte, "iB", "B", 1, 2);
   EXPECT_PRIMITIVE_FIELD(o, Char, "iC", "C", 'a', 'b');
   EXPECT_PRIMITIVE_FIELD(o, Double, "iD", "D", 1.0, 2.0);
@@ -878,19 +1227,19 @@
   runtime_->Start();
 
   jclass c = env_->FindClass("AllFields");
-  ASSERT_TRUE(c != NULL);
+  ASSERT_NE(c, nullptr);
   jobject o = env_->AllocObject(c);
-  ASSERT_TRUE(o != NULL);
+  ASSERT_NE(o, nullptr);
 
   jstring s1 = env_->NewStringUTF("hello");
-  ASSERT_TRUE(s1 != NULL);
+  ASSERT_NE(s1, nullptr);
   jstring s2 = env_->NewStringUTF("world");
-  ASSERT_TRUE(s2 != NULL);
+  ASSERT_NE(s2, nullptr);
 
   jfieldID s_fid = env_->GetStaticFieldID(c, "sObject", "Ljava/lang/Object;");
-  ASSERT_TRUE(s_fid != NULL);
+  ASSERT_NE(s_fid, nullptr);
   jfieldID i_fid = env_->GetFieldID(c, "iObject", "Ljava/lang/Object;");
-  ASSERT_TRUE(i_fid != NULL);
+  ASSERT_NE(i_fid, nullptr);
 
   env_->SetStaticObjectField(c, s_fid, s1);
   ASSERT_TRUE(env_->IsSameObject(s1, env_->GetStaticObjectField(c, s_fid)));
@@ -903,27 +1252,27 @@
   ASSERT_TRUE(env_->IsSameObject(s2, env_->GetObjectField(o, i_fid)));
 }
 
-TEST_F(JniInternalTest, NewLocalRef_NULL) {
-  EXPECT_TRUE(env_->NewLocalRef(NULL) == NULL);
+TEST_F(JniInternalTest, NewLocalRef_nullptr) {
+  EXPECT_EQ(env_->NewLocalRef(nullptr), nullptr);
 }
 
 TEST_F(JniInternalTest, NewLocalRef) {
   jstring s = env_->NewStringUTF("");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_NE(s, nullptr);
   jobject o = env_->NewLocalRef(s);
-  EXPECT_TRUE(o != NULL);
-  EXPECT_TRUE(o != s);
+  EXPECT_NE(o, nullptr);
+  EXPECT_NE(o, s);
 
   EXPECT_EQ(JNILocalRefType, env_->GetObjectRefType(o));
 }
 
-TEST_F(JniInternalTest, DeleteLocalRef_NULL) {
-  env_->DeleteLocalRef(NULL);
+TEST_F(JniInternalTest, DeleteLocalRef_nullptr) {
+  env_->DeleteLocalRef(nullptr);
 }
 
 TEST_F(JniInternalTest, DeleteLocalRef) {
   jstring s = env_->NewStringUTF("");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_NE(s, nullptr);
   env_->DeleteLocalRef(s);
 
   // Currently, deleting an already-deleted reference is just a CheckJNI warning.
@@ -937,9 +1286,9 @@
   }
 
   s = env_->NewStringUTF("");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_NE(s, nullptr);
   jobject o = env_->NewLocalRef(s);
-  ASSERT_TRUE(o != NULL);
+  ASSERT_NE(o, nullptr);
 
   env_->DeleteLocalRef(s);
   env_->DeleteLocalRef(o);
@@ -951,7 +1300,7 @@
   // Android historically treated it, and it's how the RI treats it. It's also the more useful
   // interpretation!
   ASSERT_EQ(JNI_OK, env_->PushLocalFrame(0));
-  env_->PopLocalFrame(NULL);
+  env_->PopLocalFrame(nullptr);
 
   // Negative capacities are not allowed.
   ASSERT_EQ(JNI_ERR, env_->PushLocalFrame(-1));
@@ -962,7 +1311,7 @@
 
 TEST_F(JniInternalTest, PushLocalFrame_PopLocalFrame) {
   jobject original = env_->NewStringUTF("");
-  ASSERT_TRUE(original != NULL);
+  ASSERT_NE(original, nullptr);
 
   jobject outer;
   jobject inner1, inner2;
@@ -988,7 +1337,7 @@
     // gets a new local reference...
     EXPECT_EQ(JNIInvalidRefType, env_->GetObjectRefType(inner2));
 
-    env_->PopLocalFrame(NULL);
+    env_->PopLocalFrame(nullptr);
   }
   EXPECT_EQ(JNILocalRefType, env_->GetObjectRefType(original));
   EXPECT_EQ(JNIInvalidRefType, env_->GetObjectRefType(outer));
@@ -996,30 +1345,30 @@
   EXPECT_EQ(JNIInvalidRefType, env_->GetObjectRefType(inner2));
 }
 
-TEST_F(JniInternalTest, NewGlobalRef_NULL) {
-  EXPECT_TRUE(env_->NewGlobalRef(NULL) == NULL);
+TEST_F(JniInternalTest, NewGlobalRef_nullptr) {
+  EXPECT_EQ(env_->NewGlobalRef(nullptr), nullptr);
 }
 
 TEST_F(JniInternalTest, NewGlobalRef) {
   jstring s = env_->NewStringUTF("");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_NE(s, nullptr);
   jobject o = env_->NewGlobalRef(s);
-  EXPECT_TRUE(o != NULL);
-  EXPECT_TRUE(o != s);
+  EXPECT_NE(o, nullptr);
+  EXPECT_NE(o, s);
 
-  // TODO: check that o is a global reference.
+  EXPECT_EQ(env_->GetObjectRefType(o), JNIGlobalRefType);
 }
 
-TEST_F(JniInternalTest, DeleteGlobalRef_NULL) {
-  env_->DeleteGlobalRef(NULL);
+TEST_F(JniInternalTest, DeleteGlobalRef_nullptr) {
+  env_->DeleteGlobalRef(nullptr);
 }
 
 TEST_F(JniInternalTest, DeleteGlobalRef) {
   jstring s = env_->NewStringUTF("");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_NE(s, nullptr);
 
   jobject o = env_->NewGlobalRef(s);
-  ASSERT_TRUE(o != NULL);
+  ASSERT_NE(o, nullptr);
   env_->DeleteGlobalRef(o);
 
   // Currently, deleting an already-deleted reference is just a CheckJNI warning.
@@ -1033,38 +1382,38 @@
   }
 
   jobject o1 = env_->NewGlobalRef(s);
-  ASSERT_TRUE(o1 != NULL);
+  ASSERT_NE(o1, nullptr);
   jobject o2 = env_->NewGlobalRef(s);
-  ASSERT_TRUE(o2 != NULL);
+  ASSERT_NE(o2, nullptr);
 
   env_->DeleteGlobalRef(o1);
   env_->DeleteGlobalRef(o2);
 }
 
-TEST_F(JniInternalTest, NewWeakGlobalRef_NULL) {
-  EXPECT_TRUE(env_->NewWeakGlobalRef(NULL) == NULL);
+TEST_F(JniInternalTest, NewWeakGlobalRef_nullptr) {
+  EXPECT_EQ(env_->NewWeakGlobalRef(nullptr),   nullptr);
 }
 
 TEST_F(JniInternalTest, NewWeakGlobalRef) {
   jstring s = env_->NewStringUTF("");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_NE(s, nullptr);
   jobject o = env_->NewWeakGlobalRef(s);
-  EXPECT_TRUE(o != NULL);
-  EXPECT_TRUE(o != s);
+  EXPECT_NE(o, nullptr);
+  EXPECT_NE(o, s);
 
-  // TODO: check that o is a weak global reference.
+  EXPECT_EQ(env_->GetObjectRefType(o), JNIWeakGlobalRefType);
 }
 
-TEST_F(JniInternalTest, DeleteWeakGlobalRef_NULL) {
-  env_->DeleteWeakGlobalRef(NULL);
+TEST_F(JniInternalTest, DeleteWeakGlobalRef_nullptr) {
+  env_->DeleteWeakGlobalRef(nullptr);
 }
 
 TEST_F(JniInternalTest, DeleteWeakGlobalRef) {
   jstring s = env_->NewStringUTF("");
-  ASSERT_TRUE(s != NULL);
+  ASSERT_NE(s, nullptr);
 
   jobject o = env_->NewWeakGlobalRef(s);
-  ASSERT_TRUE(o != NULL);
+  ASSERT_NE(o, nullptr);
   env_->DeleteWeakGlobalRef(o);
 
   // Currently, deleting an already-deleted reference is just a CheckJNI warning.
@@ -1078,21 +1427,21 @@
   }
 
   jobject o1 = env_->NewWeakGlobalRef(s);
-  ASSERT_TRUE(o1 != NULL);
+  ASSERT_NE(o1, nullptr);
   jobject o2 = env_->NewWeakGlobalRef(s);
-  ASSERT_TRUE(o2 != NULL);
+  ASSERT_NE(o2, nullptr);
 
   env_->DeleteWeakGlobalRef(o1);
   env_->DeleteWeakGlobalRef(o2);
 }
 
 TEST_F(JniInternalTest, Throw) {
-  EXPECT_EQ(JNI_ERR, env_->Throw(NULL));
+  EXPECT_EQ(JNI_ERR, env_->Throw(nullptr));
 
   jclass exception_class = env_->FindClass("java/lang/RuntimeException");
-  ASSERT_TRUE(exception_class != NULL);
+  ASSERT_TRUE(exception_class != nullptr);
   jthrowable exception = reinterpret_cast<jthrowable>(env_->AllocObject(exception_class));
-  ASSERT_TRUE(exception != NULL);
+  ASSERT_TRUE(exception != nullptr);
 
   EXPECT_EQ(JNI_OK, env_->Throw(exception));
   EXPECT_TRUE(env_->ExceptionCheck());
@@ -1102,10 +1451,10 @@
 }
 
 TEST_F(JniInternalTest, ThrowNew) {
-  EXPECT_EQ(JNI_ERR, env_->Throw(NULL));
+  EXPECT_EQ(JNI_ERR, env_->Throw(nullptr));
 
   jclass exception_class = env_->FindClass("java/lang/RuntimeException");
-  ASSERT_TRUE(exception_class != NULL);
+  ASSERT_TRUE(exception_class != nullptr);
 
   jthrowable thrown_exception;
 
@@ -1115,7 +1464,7 @@
   env_->ExceptionClear();
   EXPECT_TRUE(env_->IsInstanceOf(thrown_exception, exception_class));
 
-  EXPECT_EQ(JNI_OK, env_->ThrowNew(exception_class, NULL));
+  EXPECT_EQ(JNI_OK, env_->ThrowNew(exception_class, nullptr));
   EXPECT_TRUE(env_->ExceptionCheck());
   thrown_exception = env_->ExceptionOccurred();
   env_->ExceptionClear();
@@ -1141,26 +1490,26 @@
   ASSERT_TRUE(started);
 
   jclass buffer_class = env_->FindClass("java/nio/Buffer");
-  ASSERT_TRUE(buffer_class != NULL);
+  ASSERT_NE(buffer_class, nullptr);
 
   char bytes[1024];
   jobject buffer = env_->NewDirectByteBuffer(bytes, sizeof(bytes));
-  ASSERT_TRUE(buffer != NULL);
+  ASSERT_NE(buffer, nullptr);
   ASSERT_TRUE(env_->IsInstanceOf(buffer, buffer_class));
-  ASSERT_TRUE(env_->GetDirectBufferAddress(buffer) == bytes);
-  ASSERT_TRUE(env_->GetDirectBufferCapacity(buffer) == sizeof(bytes));
+  ASSERT_EQ(env_->GetDirectBufferAddress(buffer), bytes);
+  ASSERT_EQ(env_->GetDirectBufferCapacity(buffer), sizeof(bytes));
 }
 
 TEST_F(JniInternalTest, MonitorEnterExit) {
-  // Create an object to torture
+  // Create an object to torture.
   jclass object_class = env_->FindClass("java/lang/Object");
-  ASSERT_TRUE(object_class != NULL);
+  ASSERT_NE(object_class, nullptr);
   jobject object = env_->AllocObject(object_class);
-  ASSERT_TRUE(object != NULL);
+  ASSERT_NE(object, nullptr);
 
   // Expected class of exceptions
   jclass imse_class = env_->FindClass("java/lang/IllegalMonitorStateException");
-  ASSERT_TRUE(imse_class != NULL);
+  ASSERT_NE(imse_class, nullptr);
 
   jthrowable thrown_exception;
 
@@ -1197,13 +1546,13 @@
   env_->ExceptionClear();
   EXPECT_TRUE(env_->IsInstanceOf(thrown_exception, imse_class));
 
-  // It's an error to call MonitorEnter or MonitorExit on NULL.
+  // It's an error to call MonitorEnter or MonitorExit on nullptr.
   {
     CheckJniAbortCatcher check_jni_abort_catcher;
-    env_->MonitorEnter(NULL);
+    env_->MonitorEnter(nullptr);
     check_jni_abort_catcher.Check("in call to MonitorEnter");
 
-    env_->MonitorExit(NULL);
+    env_->MonitorExit(nullptr);
     check_jni_abort_catcher.Check("in call to MonitorExit");
   }
 }
@@ -1215,7 +1564,7 @@
 
   jint err = vm_->DetachCurrentThread();
   EXPECT_EQ(JNI_ERR, err);
-  vm_->AttachCurrentThread(&env_, NULL);  // need attached thread for CommonRuntimeTest::TearDown
+  vm_->AttachCurrentThread(&env_, nullptr);  // need attached thread for CommonRuntimeTest::TearDown
 }
 
 }  // namespace art