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libraries/lvgl/tests/README.md

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+# Tests for LVGL
+
+The tests in the folder can be run locally and automatically by GitHub CI.
+
+## Running locally
+
+### Requirements (Linux)
+
+Install requirements by:
+
+```sh
+scripts/install-prerequisites.sh
+```
+
+### Run test
+1. Run all executable tests with `./tests/main.py test`.
+2. Build all build-only tests with `./tests/main.py build`.
+3. Clean prior test build, build all build-only tests,
+   run executable tests, and generate code coverage
+   report `./tests/main.py --clean --report build test`.
+4. You can re-generate the test images by adding option `--update-image`.
+   It relies on scripts/LVGLImage.py, which requires pngquant and pypng.
+   You can run below command firstly and follow instructions in logs to install them.
+   `./tests/main.py --update-image test`
+   Note that different version of pngquant may generate different images.
+   As of now the generated image on CI uses pngquant 2.13.1-1.
+
+For full information on running tests run: `./tests/main.py --help`.
+
+## Running automatically
+
+GitHub's CI automatically runs these tests on pushes and pull requests to `master` and `releasev8.*` branches.
+
+## Directory structure
+- `src` Source files of the tests
+    - `test_cases` The written tests,
+    - `test_runners` Generated automatically from the files in `test_cases`.
+    - other miscellaneous files and folders
+- `ref_imgs` - Reference images for screenshot compare
+- `report` - Coverage report. Generated if the `report` flag was passed to `./main.py`
+- `unity` Source files of the test engine
+
+## Add new tests
+
+### Create new test file
+New test needs to be added into the `src/test_cases` folder. The name of the files should look like `test_<name>.c`. The basic skeleton of a test file copy `_test_template.c`.
+
+### Asserts
+See the list of asserts [here](https://github.com/ThrowTheSwitch/Unity/blob/master/docs/UnityAssertionsReference.md).
+
+There are some custom, LVGL specific asserts:
+- `TEST_ASSERT_EQUAL_SCREENSHOT("image1.png")` Render the active screen and compare its content with an image in the `ref_imgs` folder.
+   - If the reference image is not found it will be created automatically from the rendered screen.
+   - If the compare fails an `<image_name>_err.png` file will be created with the rendered content next to the reference image.
+- `TEST_ASSERT_EQUAL_COLOR(color1, color2)` Compare two colors.
+