Add test for SkRegion::writeToMemory.

tests/RegionTest.cpp

 /*
  * Copyright 2011 Google Inc.
  *
  * Use of this source code is governed by a BSD-style license that can be
  * found in the LICENSE file.
  */
 
 #include "SkPath.h"
 #include "SkRandom.h"
 #include "SkRegion.h"
@@ skipping 244 matching lines @@
             rand_rect(&rect[j], rand);
         }
         REPORTER_ASSERT(reporter, test_rects(rect, N));
     }
 
     test_proc(reporter, contains_proc);
     test_proc(reporter, intersects_proc);
     test_empties(reporter);
     test_fromchrome(reporter);
 }
+
+// Test that writeToMemory reports the same number of bytes whether there was a
+// buffer to write to or not.
+static void test_write(const SkRegion& region, skiatest::Reporter* r) {
+    const size_t bytesNeeded = region.writeToMemory(NULL);
+    SkAutoMalloc storage(bytesNeeded);
+    const size_t bytesWritten = region.writeToMemory(storage.get());
+    REPORTER_ASSERT(r, bytesWritten == bytesNeeded);
+}
+
+DEF_TEST(Region_writeToMemory, r) {
+    // Test an empty region.
+    SkRegion region;
+    REPORTER_ASSERT(r, region.isEmpty());
+    test_write(region, r);
+
+    // Test a rectangular region
+    bool nonEmpty = region.setRect(0, 0, 50, 50);
+    REPORTER_ASSERT(r, nonEmpty);
+    REPORTER_ASSERT(r, region.isRect());
+    test_write(region, r);
+
+    // Test a complex region
+    nonEmpty = region.op(50, 50, 100, 100, SkRegion::kUnion_Op);
+    REPORTER_ASSERT(r, nonEmpty);
+    REPORTER_ASSERT(r, region.isComplex());
+    test_write(region, r);
+}