Mojo C bindings library pt1: MojomBuffer

mojo/public/c/bindings/tests/buffer_unittest.cc

Index: mojo/public/c/bindings/tests/buffer_unittest.cc
diff --git a/mojo/public/c/bindings/tests/buffer_unittest.cc b/mojo/public/c/bindings/tests/buffer_unittest.cc
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+++ b/mojo/public/c/bindings/tests/buffer_unittest.cc
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+// Copyright 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 "mojo/public/c/bindings/buffer.h"
+
+#include <stdint.h>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+TEST(MojomBufferTest, RoundTo8) {
+  char buffer[100];
+  struct MojomBuffer mbuf = {
+      buffer, sizeof(buffer),
+      0,  // num_bytes_used
+  };
+
+  // This should actually allocate 8 bytes:
+  EXPECT_EQ(buffer, MojomBuffer_Allocate(&mbuf, 6));
+  EXPECT_EQ(8ul, mbuf.num_bytes_used);
+  // The start of the next buffer is buffer + 8 bytes:
+  EXPECT_EQ(buffer + 8, MojomBuffer_Allocate(&mbuf, 6));
+  EXPECT_EQ(16ul, mbuf.num_bytes_used);
+  // 8-bye allocation results in 8-byte allocation.
+  EXPECT_EQ(buffer + 16, MojomBuffer_Allocate(&mbuf, 8));
+  EXPECT_EQ(24ul, mbuf.num_bytes_used);
+  // Allocate 0 bytes.
+  EXPECT_EQ(buffer + 24ul, MojomBuffer_Allocate(&mbuf, 0));
+  EXPECT_EQ(24ul, mbuf.num_bytes_used);
+}
+
+TEST(MojomBufferTest, Failure) {
+  char buffer[100];
+  struct MojomBuffer mbuf = {
+      buffer, sizeof(buffer),
+      0,  // num_bytes_used
+  };
+
+  // Allocate too much space.
+  EXPECT_EQ(NULL, MojomBuffer_Allocate(&mbuf, sizeof(buffer) + 10));
+
+  // Setup the buffer data so that it will overflow.
+  mbuf.num_bytes_used = UINT32_MAX - 7;  // This divides by 8.
+  mbuf.buf_size = UINT32_MAX;
+
+  // Rounds to 8, and allocates more than it has:
+  EXPECT_EQ(NULL, MojomBuffer_Allocate(&mbuf, 1));
+}
+
+}  // namespace