Add unit tests for ShellSubscriber and fix a bug

Test: statsd_test
Change-Id: Iaf0558ec2a2dc190bedb240da8019868266ec8f5
diff --git a/cmds/statsd/Android.mk b/cmds/statsd/Android.mk
index 27c5a17..838eff6 100644
--- a/cmds/statsd/Android.mk
+++ b/cmds/statsd/Android.mk
@@ -227,7 +227,8 @@
     tests/e2e/Anomaly_count_e2e_test.cpp \
     tests/e2e/Anomaly_duration_sum_e2e_test.cpp \
     tests/e2e/ConfigTtl_e2e_test.cpp \
-    tests/e2e/PartialBucket_e2e_test.cpp
+    tests/e2e/PartialBucket_e2e_test.cpp \
+    tests/shell/ShellSubscriber_test.cpp
 
 LOCAL_STATIC_LIBRARIES := \
     $(statsd_common_static_libraries) \
diff --git a/cmds/statsd/src/shell/ShellSubscriber.cpp b/cmds/statsd/src/shell/ShellSubscriber.cpp
index 3cd49d7..1306a46 100644
--- a/cmds/statsd/src/shell/ShellSubscriber.cpp
+++ b/cmds/statsd/src/shell/ShellSubscriber.cpp
@@ -113,12 +113,12 @@
 
     for (const auto& matcher : mPushedMatchers) {
         if (matchesSimple(*mUidMap, matcher, event)) {
+            event.ToProto(mProto);
             // First write the payload size.
             size_t bufferSize = mProto.size();
             write(mOutput, &bufferSize, sizeof(bufferSize));
 
             // Then write the payload.
-            event.ToProto(mProto);
             mProto.flush(mOutput);
             mProto.clear();
             break;
@@ -137,4 +137,4 @@
 
 }  // namespace statsd
 }  // namespace os
-}  // namespace android
\ No newline at end of file
+}  // namespace android
diff --git a/cmds/statsd/tests/shell/ShellSubscriber_test.cpp b/cmds/statsd/tests/shell/ShellSubscriber_test.cpp
new file mode 100644
index 0000000..b380b03
--- /dev/null
+++ b/cmds/statsd/tests/shell/ShellSubscriber_test.cpp
@@ -0,0 +1,136 @@
+// 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 <unistd.h>
+#include "frameworks/base/cmds/statsd/src/atoms.pb.h"
+#include "frameworks/base/cmds/statsd/src/shell/shell_config.pb.h"
+#include "src/shell/ShellSubscriber.h"
+#include "tests/metrics/metrics_test_helper.h"
+
+#include <stdio.h>
+#include <vector>
+
+using namespace android::os::statsd;
+using android::sp;
+using std::vector;
+using testing::NaggyMock;
+
+#ifdef __ANDROID__
+
+class MyResultReceiver : public BnResultReceiver {
+public:
+    Mutex mMutex;
+    Condition mCondition;
+    bool mHaveResult = false;
+    int32_t mResult = 0;
+
+    virtual void send(int32_t resultCode) {
+        AutoMutex _l(mMutex);
+        mResult = resultCode;
+        mHaveResult = true;
+        mCondition.signal();
+    }
+
+    int32_t waitForResult() {
+        AutoMutex _l(mMutex);
+        mCondition.waitRelative(mMutex, 1000000000);
+        return mResult;
+    }
+};
+
+TEST(ShellSubscriberTest, testPushedSubscription) {
+    // set up 2 pipes for read/write config and data
+    int fds_config[2];
+    ASSERT_EQ(0, pipe(fds_config));
+
+    int fds_data[2];
+    ASSERT_EQ(0, pipe(fds_data));
+
+    // create a simple config to get screen events
+    ShellSubscription config;
+    config.add_pushed()->set_atom_id(29);
+
+    size_t bufferSize = config.ByteSize();
+
+    // write the config to pipe, first write size of the config
+    vector<uint8_t> size_buffer(sizeof(bufferSize));
+    std::memcpy(size_buffer.data(), &bufferSize, sizeof(bufferSize));
+    write(fds_config[1], &bufferSize, sizeof(bufferSize));
+    // then write config itself
+    vector<uint8_t> buffer(bufferSize);
+    config.SerializeToArray(&buffer[0], bufferSize);
+    write(fds_config[1], buffer.data(), bufferSize);
+    close(fds_config[1]);
+
+    // create a shell subscriber.
+    sp<MockUidMap> uidMap = new NaggyMock<MockUidMap>();
+    sp<ShellSubscriber> shellClient = new ShellSubscriber(uidMap);
+    sp<MyResultReceiver> resultReceiver = new MyResultReceiver();
+
+    LogEvent event1(29, 1000);
+    event1.write(2);
+    event1.init();
+
+    // mimic a binder thread that a shell subscriber runs on. it would block.
+    std::thread reader([&resultReceiver, &fds_config, &fds_data, &shellClient] {
+        shellClient->startNewSubscription(fds_config[0], fds_data[1], resultReceiver);
+    });
+    reader.detach();
+
+    // let the shell subscriber to receive the config from pipe.
+    std::this_thread::sleep_for(100ms);
+
+    // send a log event that matches the config.
+    std::thread log_reader([&shellClient, &event1] { shellClient->onLogEvent(event1); });
+    log_reader.detach();
+
+    if (log_reader.joinable()) {
+        log_reader.join();
+    }
+
+    // wait for the data to be written.
+    std::this_thread::sleep_for(100ms);
+
+    // this is the expected screen event atom.
+    Atom atom;
+    atom.mutable_screen_state_changed()->set_state(
+            ::android::view::DisplayStateEnum::DISPLAY_STATE_ON);
+
+    int atom_size = atom.ByteSize();
+
+    // now read from the pipe. firstly read the atom size.
+    size_t dataSize = 0;
+    EXPECT_EQ((int)sizeof(dataSize), read(fds_data[0], &dataSize, sizeof(dataSize)));
+    EXPECT_EQ(atom_size, (int)dataSize);
+
+    // then read that much data which is the atom in proto binary format
+    vector<uint8_t> dataBuffer(dataSize);
+    EXPECT_EQ((int)dataSize, read(fds_data[0], dataBuffer.data(), dataSize));
+
+    // make sure the received bytes can be parsed to an atom
+    Atom receivedAtom;
+    EXPECT_TRUE(receivedAtom.ParseFromArray(dataBuffer.data(), dataSize) != 0);
+
+    // serialze the expected atom to bytes. and compare. to make sure they are the same.
+    vector<uint8_t> atomBuffer(atom_size);
+    atom.SerializeToArray(&atomBuffer[0], atom_size);
+    EXPECT_EQ(atomBuffer, dataBuffer);
+    close(fds_data[0]);
+}
+
+#else
+GTEST_LOG_(INFO) << "This test does nothing.\n";
+#endif