ci(tests) use common script to install development prereqs (#2504)

Simplified workflow and documentation, by moving the
development package prerequisites into a new build script
`scripts/install-prerequisites.sh`.

Also, moved prerequisite installation into its own CI step and
removed explicit working directory change as it is no longer
needed (`main.py` does it).

.github/workflows/ccpp.yml

@@ -14,8 +14,10 @@ jobs:
     steps:
     - uses: actions/checkout@v2
     - uses: ammaraskar/gcc-problem-matcher@master
+    - name: Install prerequisites
+      run: scripts/install-prerequisites.sh
     - name: Run tests
-      run: sudo apt-get install libpng-dev ruby-full gcovr; cd tests; python ./main.py report
+      run: python tests/main.py report
     - name: Upload coverage to Codecov
       uses: codecov/codecov-action@v1
       if: github.event_name == 'push'

scripts/install-prerequisites.sh

@@ -0,0 +1,8 @@
+#!/usr/bin/sh
+
+# Install Linux package prerequisites needed for LVGL development
+# and testing. Some less-common development packages are not included
+# here, such as MicroPython and PC simulator packages.
+#
+# Note: This script is run by the CI workflows.
+sudo apt install gcc python3 libpng-dev ruby-full gcovr cmake

tests/README.md

@@ -5,11 +5,12 @@ The tests in the folder can be run locally and automatically by GitHub CI.
 ## Running locally
 
 ### Requirements (Linux)
-1. Be sure GCC and Python3 are installed.
-2. Install [cmake](https://cmake.org/) with `sudo apt install cmake`.
-3. Install [gcovr](https://gcovr.com/en/stable/index.html) with `sudo apt install gcovr`
-4. Install Ruby with `sudo apt install ruby-full`
-5. Install libpng development package with `sudo apt install libpng-dev`
+
+Install requirements by:
+
+```sh
+scripts/install-prerequisites.sh
+```
 
 ### Run test
 1. Enter `lvgl/tests/`