Add ScopedObjCClassSwizzler in base/mac, absorbs objc_method_swizzle and ScopedClassSwizzler

ui/gfx/mac/coordinate_conversion_unittest.mm

+// Copyright 2014 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.
+
+#import "ui/gfx/mac/coordinate_conversion.h"
+
+#import <Cocoa/Cocoa.h>
+
+#include "base/macros.h"
+#include "base/memory/scoped_ptr.h"
+#import "base/test/scoped_class_swizzler_mac.h"
+#import "testing/platform_test.h"
+#include "ui/gfx/geometry/rect.h"
+
+const int kTestWidth = 320;
+const int kTestHeight = 200;
+
+// Class to donate an implementation of -[NSScreen frame] that provides a known
+// value for robust tests.
+@interface MacCoordinateConversionTestScreenDonor : NSObject
+

[Robert Sesek, 2014/07/21 15:59:01]

optional: Feel free to omit blank lines around methods in these in-impl files.

[tapted, 2014/07/22 12:53:49]

Done.

+- (NSRect)frame;
+
+@end
+
+@implementation MacCoordinateConversionTestScreenDonor
+
+- (NSRect)frame {
+  return NSMakeRect(0, 0, kTestWidth, kTestHeight);
+}
+
+@end
+
+namespace gfx {
+namespace {
+
+class MacCoordinateConversionTest : public PlatformTest {
+ public:
+  MacCoordinateConversionTest() {}
+
+  // Overridden from testing::Test:
+  virtual void SetUp() OVERRIDE;
+  virtual void TearDown() OVERRIDE;
+
+ private:
+  scoped_ptr<base::ScopedClassSwizzler> swizzle_frame_;
+
+  DISALLOW_COPY_AND_ASSIGN(MacCoordinateConversionTest);
+};
+
+void MacCoordinateConversionTest::SetUp() {
+  // Before swizzling, do a sanity check that the primary screen's origin is
+  // (0, 0). This should always be true.
+  NSRect primary_screen_frame = [[[NSScreen screens] objectAtIndex:0] frame];
+  EXPECT_EQ(0, primary_screen_frame.origin.x);
+  EXPECT_EQ(0, primary_screen_frame.origin.y);
+
+  swizzle_frame_.reset(new base::ScopedClassSwizzler(
+      [NSScreen class],
+      [MacCoordinateConversionTestScreenDonor class],
+      @selector(frame)));
+
+  primary_screen_frame = [[[NSScreen screens] objectAtIndex:0] frame];
+  EXPECT_EQ(kTestWidth, primary_screen_frame.size.width);
+  EXPECT_EQ(kTestHeight, primary_screen_frame.size.height);
+}
+
+void MacCoordinateConversionTest::TearDown() {
+  swizzle_frame_.reset();
+}
+
+}  // namespace
+
+// Tests for coordinate conversion on Mac. Start with the following setup:
+// AppKit ....... gfx
+// 199              0
+// 189             10   Window of height 40 fills in pixel
+// 179  ---------  20   at index 20
+// 169  |       |  30   through
+// ...  :       :  ..   to
+// 150  |       |  49   pixel
+// 140  ---------  59   at index 59
+// 130             69   (inclusive).
+//  ..             ..
+//   0            199
+TEST_F(MacCoordinateConversionTest, ScreenRectToFromNSRect) {
+  Rect gfx_rect = Rect(10, 20, 30, 40);
+  NSRect ns_rect = ScreenRectToNSRect(gfx_rect);
+  EXPECT_TRUE(NSEqualRects(NSMakeRect(10, 140, 30, 40), ns_rect));
+  EXPECT_EQ(gfx_rect.ToString(), ScreenRectFromNSRect(ns_rect).ToString());
+
+  // Window in a screen to the left of the primary screen.
+  gfx_rect = Rect(-40, 20, 30, 40);
+  ns_rect = ScreenRectToNSRect(gfx_rect);
+  EXPECT_TRUE(NSEqualRects(NSMakeRect(-40, 140, 30, 40), ns_rect));
+  EXPECT_EQ(gfx_rect.ToString(), ScreenRectFromNSRect(ns_rect).ToString());
+
+  // Window in a screen below the primary screen.
+  gfx_rect = Rect(10, 220, 30, 40);
+  ns_rect = ScreenRectToNSRect(gfx_rect);
+  EXPECT_TRUE(NSEqualRects(NSMakeRect(10, -60, 30, 40), ns_rect));
+  EXPECT_EQ(gfx_rect.ToString(), ScreenRectFromNSRect(ns_rect).ToString());
+
+  // Window in a screen below and to the left primary screen.
+  gfx_rect = Rect(-40, 220, 30, 40);
+  ns_rect = ScreenRectToNSRect(gfx_rect);
+  EXPECT_TRUE(NSEqualRects(NSMakeRect(-40, -60, 30, 40), ns_rect));
+  EXPECT_EQ(gfx_rect.ToString(), ScreenRectFromNSRect(ns_rect).ToString());
+}
+
+}  // namespace gfx