Introduce ArrayView::subview function

webrtc/base/array_view_unittest.cc

 /*
  *  Copyright 2015 The WebRTC Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #include <algorithm>
 #include <string>
 #include <vector>
 
 #include "webrtc/base/array_view.h"
 #include "webrtc/base/buffer.h"
 #include "webrtc/base/checks.h"
 #include "webrtc/base/gunit.h"
+#include "webrtc/test/gmock.h"
 
 namespace rtc {
 
 namespace {
 
+using ::testing::ElementsAre;
+using ::testing::IsEmpty;
+
 template <typename T>
 void Call(ArrayView<T>) {}
 
 }  // namespace
 
 TEST(ArrayViewTest, TestConstructFromPtrAndArray) {
   char arr[] = "Arrr!";
   const char carr[] = "Carrr!";
   Call<const char>(arr);
   Call<const char>(carr);
@@ skipping 191 matching lines @@
 TEST(ArrayViewTest, TestCompare) {
   int a[] = {1, 2, 3};
   int b[] = {1, 2, 3};
   EXPECT_EQ(ArrayView<int>(a), ArrayView<int>(a));
   EXPECT_EQ(ArrayView<int>(), ArrayView<int>());
   EXPECT_NE(ArrayView<int>(a), ArrayView<int>(b));
   EXPECT_NE(ArrayView<int>(a), ArrayView<int>());
   EXPECT_NE(ArrayView<int>(a), ArrayView<int>(a, 2));
 }
 
+TEST(ArrayViewTest, TestSubView) {
+  int a[] = {1, 2, 3};
+  ArrayView<int> av(a);
+
+  EXPECT_EQ(av.subview(0), av);
+
+  EXPECT_THAT(av.subview(1), ElementsAre(2, 3));
+  EXPECT_THAT(av.subview(2), ElementsAre(3));
+  EXPECT_THAT(av.subview(3), IsEmpty());
+  EXPECT_THAT(av.subview(4), IsEmpty());
+
+  EXPECT_THAT(av.subview(1, 0), IsEmpty());
+  EXPECT_THAT(av.subview(1, 1), ElementsAre(2));
+  EXPECT_THAT(av.subview(1, 2), ElementsAre(2, 3));
+  EXPECT_THAT(av.subview(1, 3), ElementsAre(2, 3));
+}
+
 }  // namespace rtc