---

title: ‘Writing Skia Tests’ linkTitle: ‘Writing Skia Tests’

We assume you have already synced Skia‘s dependencies and set up Skia’s build system.

python2 tools/git-sync-deps
bin/gn gen out/Debug
bin/gn gen out/Release --args='is_debug=false'

Writing a Unit Test

1. Add a file tests/NewUnitTest.cpp:

   /*
    * Copyright ........
    *
    * Use of this source code is governed by a BSD-style license
    * that can be found in the LICENSE file.
    */
   #include "Test.h"
   DEF_TEST(NewUnitTest, reporter) {
       if (1 + 1 != 2) {
           ERRORF(reporter, "%d + %d != %d", 1, 1, 2);
       }
       bool lifeIsGood = true;
       REPORTER_ASSERT(reporter, lifeIsGood);
   }
   

2. Add NewUnitTest.cpp to gn/tests.gni.

3. Recompile and run test:

   ninja -C out/Debug dm
   out/Debug/dm --match NewUnitTest
   

Writing a Rendering Test

1. Add a file gm/newgmtest.cpp:

   /*
    * Copyright ........
    *
    * Use of this source code is governed by a BSD-style license
    * that can be found in the LICENSE file.
    */
   #include "gm.h"
   DEF_SIMPLE_GM(newgmtest, canvas, 128, 128) {
       canvas->clear(SK_ColorWHITE);
       SkPaint p;
       p.setStrokeWidth(2);
       canvas->drawLine(16, 16, 112, 112, p);
   }
   

2. Add newgmtest.cpp to gn/gm.gni.

3. Recompile and run test:

   ninja -C out/Debug dm
   out/Debug/dm --match newgmtest
   

4. Run the GM inside Viewer:

   ninja -C out/Debug viewer
   out/Debug/viewer --slide GM_newgmtest
   

Writing a Benchmark Test

1. Add a file bench/FooBench.cpp:

   /*
    * Copyright ........
    *
    * Use of this source code is governed by a BSD-style license
    * that can be found in the LICENSE file.
    */
   #include "Benchmark.h"
   #include "SkCanvas.h"
   namespace {
   class FooBench : public Benchmark {
   public:
       FooBench() {}
       virtual ~FooBench() {}
   protected:
       const char* onGetName() override { return "Foo"; }
       SkIPoint onGetSize() override { return SkIPoint{100, 100}; }
       void onDraw(int loops, SkCanvas* canvas) override {
           while (loops-- > 0) {
               canvas->drawLine(0.0f, 0.0f, 100.0f, 100.0f, SkPaint());
           }
       }
   };
   }  // namespace
   DEF_BENCH(return new FooBench;)
   

2. Add FooBench.cpp to gn/bench.gni.

3. Recompile and run nanobench:

   ninja -C out/Release nanobench
   out/Release/nanobench --match Foo