skia2/site/dev/testing/tests.md

Writing Skia Tests
==================

+   [Unit Tests](#test)
+   [Rendering Tests](#gm)
+   [Benchmark Tests](#bench)

We assume you have already synced Skia's dependecies and set up Skia's build system.

<!--?prettify lang=sh?-->

    python bin/sync
    gn gen out/Debug
    gn gen out/Release --args='is_debug=false'

<span id="test"></span>

Writing a Unit Test
-------------------

1.  Add a file `tests/NewUnitTest.cpp`:

    <!--?prettify lang=cc?-->

        /*
         * 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:

    <!--?prettify lang=sh?-->

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

<span id="gm"></span>

Writing a Rendering Test
------------------------

1.  Add a file `gm/newgmtest.cpp`:

    <!--?prettify lang=cc?-->

        /*
         * 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:

    <!--?prettify lang=sh?-->

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

4.  Run the GM inside SampleApp:

    <!--?prettify lang=sh?-->

        ninja -C out/Debug SampleApp
        out/Debug/SampleApp --slide GM:newgmtest

<span id="bench"></span>

Writing a Benchmark Test
------------------------

1.  Add a file `bench/FooBench.cpp`:

    <!--?prettify lang=cc?-->

        /*
         * 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:

    <!--?prettify lang=sh?-->

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