GH-28: Write the unit tests and setup CI (GH-36)

* Fix the JSON thumbnail when `--base` is given
* Add PyAV to the dependency list
* Fix the relative path issue of `listdir`
* Add .avi (ordinary) and .ogv (stream) videos for tests
* Write unit tests for primary workflows

Author: ArtyomVancyan

.github/workflows/tests.yml

@@ -0,0 +1,25 @@
+name: Tests
+
+on:
+  - pull_request
+
+jobs:
+  test:
+    runs-on: ${{ matrix.os }}
+    strategy:
+      matrix:
+        os: [ ubuntu-latest, windows-latest, macOS-latest ]
+        python-version: [ "3.7", "3.8", "3.9" ]
+
+    steps:
+      - uses: actions/checkout@v2
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install tox tox-gh-actions
+      - name: Test with tox
+        run: tox

.gitignore

@@ -1,3 +1,2 @@
-*/package-lock.json
-*/node_modules
-*/build
+.idea
+.tox

README.md

@@ -1,5 +1,7 @@
 # Thumbnails <img src="https://github.com/pysnippet.png" align="right" height="64" />
 
+[![PyPI](https://img.shields.io/pypi/v/thumbnails.svg)](https://pypi.org/project/thumbnails/)
+[![Tests](https://github.com/pysnippet/thumbnails/actions/workflows/tests.yml/badge.svg)](https://github.com/pysnippet/thumbnails/actions/workflows/tests.yml)
 [![Codacy Badge](https://app.codacy.com/project/badge/Grade/ab5414af4c9546fe97ad64365e2a66f0)](https://www.codacy.com?utm_source=github.com&amp;utm_medium=referral&amp;utm_content=pysnippet/thumbnails&amp;utm_campaign=Badge_Grade)
 [![License](https://img.shields.io/pypi/l/thumbnails.svg)](https://github.com/pysnippet/thumbnails/blob/master/LICENSE)
 
@@ -28,6 +30,30 @@ Video.js also can handle **JSON** formatted thumbnails' metadata, and this tool
 thumbnails --help
 ```
 
+[//]: # (TODO: usage for CLI and python API)
+
+## Development
+
+Install the dependencies:
+```bash
+python3 -m pip install -r requirements.txt
+```
+
+Install the development dependencies:
+```bash
+python3 -m pip install -r requirements-dev.txt
+```
+
+Install the package in editable mode:
+```bash
+python3 -m pip install -e .
+```
+
+Run the tests to ensure everything is working before opening a PR:
+```bash
+tox
+```
+
 ## Contribute
 
 Everyone is welcome to contribute to this project. Please read the [contribution guidelines](https://github.com/pysnippet/instructions#readme)

plyr/README.md

@@ -0,0 +1,7 @@
+[build-system]
+requires = ["setuptools>=42.0", "wheel"]
+build-backend = "setuptools.build_meta"
+
+[tool.pytest.ini_options]
+testpaths = ["tests"]
+filterwarnings = ["ignore::DeprecationWarning"]

plyr/package.json

@@ -0,0 +1,2 @@
+tox==3.24.3
+pytest==6.2.5