Add a test for MemoryMonitorAndroid::GetFreeMemoryUntilCriticalMB

content/browser/memory/memory_monitor_android_unittest.cc

 // Copyright (c) 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "content/browser/memory/memory_monitor_android.h"
 
+#include "base/memory/ptr_util.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace content {
 
+class MockMemoryMonitorAndroidDelegate : public MemoryMonitorAndroid::Delegate {
+ public:
+  MockMemoryMonitorAndroidDelegate() {}
+  ~MockMemoryMonitorAndroidDelegate() override {}
+
+  using MemoryInfo = MemoryMonitorAndroid::MemoryInfo;
+
+  void SetMemoryInfo(const MemoryInfo& info) {
+    memcpy(&memory_info_, &info, sizeof(memory_info_));
+  }
+
+  void GetMemoryInfo(MemoryInfo* out) override {
+    memcpy(out, &memory_info_, sizeof(memory_info_));
+  }
+
+ private:
+  MemoryInfo memory_info_;
+
+  DISALLOW_COPY_AND_ASSIGN(MockMemoryMonitorAndroidDelegate);
+};
+
 class MemoryMonitorAndroidTest : public testing::Test {
  public:
-  MemoryMonitorAndroidTest() : monitor_(MemoryMonitorAndroid::Create()) {}
+  MemoryMonitorAndroidTest() : monitor_(MemoryMonitorAndroid::Create()) {
+    auto mock_delegate = base::WrapUnique(new MockMemoryMonitorAndroidDelegate);
+    mocked_monitor_.reset(
+        new MemoryMonitorAndroid(std::move(mock_delegate)));
+  }
 
  protected:
+  static const int kMBShift = 20;
+
+  MockMemoryMonitorAndroidDelegate* mock_delegate() {
+    return static_cast<MockMemoryMonitorAndroidDelegate*>(
+        mocked_monitor_->delegate());
+  }
+
   std::unique_ptr<MemoryMonitorAndroid> monitor_;
+  std::unique_ptr<MemoryMonitorAndroid> mocked_monitor_;
 };
 
 TEST_F(MemoryMonitorAndroidTest, GetMemoryInfo) {
   MemoryMonitorAndroid::MemoryInfo info;
   monitor_->GetMemoryInfo(&info);
   EXPECT_GT(info.avail_mem, 0);
   EXPECT_GT(info.threshold, 0);
   EXPECT_GT(info.total_mem, 0);
 }
 
+TEST_F(MemoryMonitorAndroidTest, GetFreeMemoryUntilCriticalMB) {
+  MemoryMonitorAndroid::MemoryInfo info = {
+    .avail_mem = 100 << kMBShift,
+    .low_memory = false,
+    .threshold = 80 << kMBShift,
+    .total_mem = 150 << kMBShift,
+  };
+  mock_delegate()->SetMemoryInfo(info);
+  EXPECT_EQ(20, mocked_monitor_->GetFreeMemoryUntilCriticalMB());
+}
+
 }  // namespace content