Add basic logging infrastructure for bugreports

Test: as follows
    - built, flashed, booted
    - "adb shell dumpsys netd" shows logs
    - tests/runtests.sh passes
Change-Id: I0e44da7f9a9cc53074ffc396b958e9e2dbcd2603
diff --git a/libnetdutils/LogTest.cpp b/libnetdutils/LogTest.cpp
new file mode 100644
index 0000000..20f3e1e
--- /dev/null
+++ b/libnetdutils/LogTest.cpp
@@ -0,0 +1,114 @@
+/*
+ * Copyright (C) 2018 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <gtest/gtest.h>
+
+#include "netdutils/Log.h"
+
+android::netdutils::LogEntry globalFunctionName() {
+    return android::netdutils::LogEntry().function(__FUNCTION__);
+}
+
+android::netdutils::LogEntry globalPrettyFunctionName() {
+    return android::netdutils::LogEntry().prettyFunction(__PRETTY_FUNCTION__);
+}
+
+namespace android {
+namespace netdutils {
+
+namespace {
+
+LogEntry functionName() {
+    return LogEntry().function(__FUNCTION__);
+}
+
+LogEntry prettyFunctionName() {
+    return LogEntry().prettyFunction(__PRETTY_FUNCTION__);
+}
+
+}  // namespace
+
+class AAA {
+  public:
+    AAA() = default;
+
+    LogEntry functionName() {
+        return LogEntry().function(__FUNCTION__);
+    }
+
+    LogEntry prettyFunctionName() {
+        return LogEntry().prettyFunction(__PRETTY_FUNCTION__);
+    }
+
+    class BBB {
+      public:
+        BBB() = default;
+
+        LogEntry functionName() {
+            return LogEntry().function(__FUNCTION__);
+        }
+
+        LogEntry prettyFunctionName() {
+            return LogEntry().prettyFunction(__PRETTY_FUNCTION__);
+        }
+    };
+};
+
+TEST(LogEntryTest, Empty) {
+    LogEntry empty;
+    EXPECT_EQ("", empty.toString());
+}
+
+TEST(LogEntryTest, GlobalFunction) {
+    EXPECT_EQ("globalFunctionName()", ::globalFunctionName().toString());
+}
+
+TEST(LogEntryTest, GlobalPrettyFunction) {
+    EXPECT_EQ("globalPrettyFunctionName()", ::globalPrettyFunctionName().toString());
+}
+
+TEST(LogEntryTest, UnnamedNamespaceFunction) {
+    const LogEntry entry = functionName();
+    EXPECT_EQ("functionName()", entry.toString());
+}
+
+TEST(LogEntryTest, UnnamedNamespacePrettyFunction) {
+    const LogEntry entry = prettyFunctionName();
+    EXPECT_EQ("prettyFunctionName()", entry.toString());
+}
+
+TEST(LogEntryTest, ClassFunction) {
+    const LogEntry entry = AAA().functionName();
+    EXPECT_EQ("functionName()", entry.toString());
+}
+
+TEST(LogEntryTest, ClassPrettyFunction) {
+    const LogEntry entry = AAA().prettyFunctionName();
+    EXPECT_EQ("AAA::prettyFunctionName()", entry.toString());
+}
+
+TEST(LogEntryTest, InnerClassFunction) {
+    const LogEntry entry = AAA::BBB().functionName();
+    EXPECT_EQ("functionName()", entry.toString());
+}
+
+TEST(LogEntryTest, InnerClassPrettyFunction) {
+    const LogEntry entry = AAA::BBB().prettyFunctionName();
+    EXPECT_EQ("BBB::prettyFunctionName()", entry.toString());
+}
+
+}  // namespace netdutils
+}  // namespace android