commit 61f796b5bed91ef78783383cae34c5e06dab03d2
author Lorenzo Colitti <lorenzo@google.com> Thu May 21 00:57:49 2020 +0900
committer Lorenzo Colitti <lorenzo@google.com> Thu May 21 23:01:42 2020 +0900
tree f1a3ecb8809aeccaa3b578bd474ebe60eccb93cd
parent 511b6d4f1fb2cc611fb397bb212aee2120f43029

Test for unexpected prefix updates in SetAndClearNat64Prefix.

Add code to check that no onNat64PrefixEvent calls were sent by
the resolver other than the ones expected by the test.

This adds a simple counter of unexpected events to the test
DnsMetricsListener. It does not offer the ability to check which
events occur and in what order, but it does at least not require
adding timeouts to ensure that the unexpected events do not
occur.

Bug: 156914456
Test: test-only change
Change-Id: Ic86f93161293b4ad5366fd9cab2e26d4a6f636c4

tests/dns_metrics_listener/dns_metrics_listener.cpp

diff --git a/tests/dns_metrics_listener/dns_metrics_listener.cpp b/tests/dns_metrics_listener/dns_metrics_listener.cpp
index 18c98d2..c3a15ed 100644
--- a/tests/dns_metrics_listener/dns_metrics_listener.cpp
+++ b/tests/dns_metrics_listener/dns_metrics_listener.cpp
@@ -33,6 +33,7 @@
                                                             const std::string& prefixString,
                                                             int32_t /*prefixLength*/) {
     std::lock_guard lock(mMutex);
+    mUnexpectedNat64PrefixUpdates++;
     if (netId == mNetId) mNat64Prefix = added ? prefixString : "";
     return ::ndk::ScopedAStatus::ok();
 }
@@ -49,15 +50,16 @@
     return ::ndk::ScopedAStatus::ok();
 }
 
-bool DnsMetricsListener::waitForNat64Prefix(ExpectNat64PrefixStatus status,
-                                            milliseconds timeout) const {
+bool DnsMetricsListener::waitForNat64Prefix(ExpectNat64PrefixStatus status, milliseconds timeout) {
     android::base::Timer t;
     while (t.duration() < timeout) {
         {
             std::lock_guard lock(mMutex);
             if ((status == EXPECT_FOUND && !mNat64Prefix.empty()) ||
-                (status == EXPECT_NOT_FOUND && mNat64Prefix.empty()))
+                (status == EXPECT_NOT_FOUND && mNat64Prefix.empty())) {
+                mUnexpectedNat64PrefixUpdates--;
                 return true;
+            }
         }
         std::this_thread::sleep_for(kRetryIntervalMs);
     }

tests/dns_metrics_listener/dns_metrics_listener.h

diff --git a/tests/dns_metrics_listener/dns_metrics_listener.h b/tests/dns_metrics_listener/dns_metrics_listener.h
index 4322296..0b36462 100644
--- a/tests/dns_metrics_listener/dns_metrics_listener.h
+++ b/tests/dns_metrics_listener/dns_metrics_listener.h
@@ -51,8 +51,14 @@
                                                      bool validated) override;
 
     // Wait for expected NAT64 prefix status until timeout.
-    bool waitForNat64Prefix(ExpectNat64PrefixStatus status,
-                            std::chrono::milliseconds timeout) const;
+    bool waitForNat64Prefix(ExpectNat64PrefixStatus status, std::chrono::milliseconds timeout)
+            EXCLUDES(mMutex);
+
+    // Returns the number of updates to the NAT64 prefix that have not yet been waited for.
+    int getUnexpectedNat64PrefixUpdates() const EXCLUDES(mMutex) {
+        std::lock_guard lock(mMutex);
+        return mUnexpectedNat64PrefixUpdates;
+    }
 
     // Wait for the expected private DNS validation result until timeout.
     bool waitForPrivateDnsValidation(const std::string& serverAddr, const bool validated);
@@ -64,6 +70,12 @@
         return mValidationRecords.find({mNetId, serverAddr}) != mValidationRecords.end();
     }
 
+    void reset() EXCLUDES(mMutex) {
+        std::lock_guard lock(mMutex);
+        mUnexpectedNat64PrefixUpdates = 0;
+        mValidationRecords.clear();
+    }
+
   private:
     typedef std::pair<int32_t, std::string> ServerKey;
 
@@ -77,6 +89,13 @@
     // The NAT64 prefix of the network |mNetId|. It is updated by the event onNat64PrefixEvent().
     std::string mNat64Prefix GUARDED_BY(mMutex);
 
+    // The number of updates to the NAT64 prefix of network |mNetId| that have not yet been waited
+    // for. Increases by 1 every time onNat64PrefixEvent is called, and decreases by 1 every time
+    // waitForNat64Prefix returns true.
+    // This allows tests to check that no unexpected events have been received without having to
+    // resort to timeouts that make the tests slower and flakier.
+    int mUnexpectedNat64PrefixUpdates GUARDED_BY(mMutex);
+
     // Used to store the data from onPrivateDnsValidationEvent.
     std::map<ServerKey, bool> mValidationRecords GUARDED_BY(mMutex);
 

tests/resolv_integration_test.cpp

diff --git a/tests/resolv_integration_test.cpp b/tests/resolv_integration_test.cpp
index d70a552..595d621 100644
--- a/tests/resolv_integration_test.cpp
+++ b/tests/resolv_integration_test.cpp
@@ -185,7 +185,11 @@
     static void TearDownTestSuite() { AIBinder_DeathRecipient_delete(sResolvDeathRecipient); }
 
   protected:
-    void SetUp() { mDnsClient.SetUp(); }
+    void SetUp() {
+        mDnsClient.SetUp();
+        sDnsMetricsListener->reset();
+    }
+
     void TearDown() {
         // Ensure the dump works at the end of each test.
         DumpResolverService();
@@ -3816,6 +3820,8 @@
 
     EXPECT_TRUE(resolvService->stopPrefix64Discovery(TEST_NETID).isOk());
     EXPECT_TRUE(WaitForNat64Prefix(EXPECT_NOT_FOUND));
+
+    EXPECT_EQ(0, sDnsMetricsListener->getUnexpectedNat64PrefixUpdates());
 }
 
 namespace {