Enhancement: Switch to GitHub Actions

.editorconfig

@@ -0,0 +1,17 @@
+root = true
+
+[*]
+charset = utf-8
+indent_size = 4
+indent_style = space
+insert_final_newline = true
+trim_trailing_whitespace = true
+
+[*.json]
+indent_size = 4
+
+[*.{yaml,yml}]
+indent_size = 2
+
+[Makefile]
+indent_style = tab

.gitattributes

@@ -0,0 +1,9 @@
+/.github/               export-ignore
+/tests/                 export-ignore
+/.codeclimate.yml       export-ignore
+/.gitattributes         export-ignore
+/.gitignore             export-ignore
+/.php_cs                export-ignore
+/infection.json         export-ignore
+/Makefile               export-ignore
+/phpunit.xml.dist       export-ignore

.github/CONTRIBUTING.md

@@ -0,0 +1,39 @@
+# CONTRIBUTING
+
+We are using [GitHub Actions](https://github.com/features/actions) as a continuous integration system.
+
+For details, take a look at the following workflow configuration files:
+
+- [`workflows/integrate.yaml`](workflows/integrate.yaml)
+
+## Tests
+
+We are using [`phpunit/phpunit`](https://github.com/sebastianbergmann/phpunit) to drive the development.
+
+Run
+
+```sh
+$ make tests
+```
+
+to run all the tests.
+
+## Extra lazy?
+
+Run
+
+```sh
+$ make
+```
+
+to run tests!
+
+## Help
+
+:bulb: Run
+
+```sh
+$ make help
+```
+
+to display a list of available targets with corresponding descriptions.

.github/workflows/integrate.yaml

@@ -0,0 +1,54 @@
+# https://help.github.com/en/categories/automating-your-workflow-with-github-actions
+
+name: "Integrate"
+
+on: # yamllint disable-line rule:truthy
+  pull_request: null
+  push:
+    branches:
+      - "master"
+
+jobs:
+  tests:
+    name: "Tests"
+
+    runs-on: "ubuntu-latest"
+
+    strategy:
+      matrix:
+        php-version:
+          - "5.4"
+          - "5.5"
+          - "5.6"
+          - "7.0"
+
+        dependencies:
+          - "locked"
+
+    steps:
+      - name: "Checkout"
+        uses: "actions/checkout@v2"
+
+      - name: "Install PHP with extensions"
+        uses: "shivammathur/setup-php@v2"
+        with:
+          coverage: "none"
+          php-version: "${{ matrix.php-version }}"
+
+      - name: "Determine composer cache directory"
+        id: "determine-composer-cache-directory"
+        run: "echo \"::set-output name=directory::$(composer config cache-dir)\""
+
+      - name: "Cache dependencies installed with composer"
+        uses: "actions/cache@v2"
+        with:
+          path: "${{ steps.determine-composer-cache-directory.outputs.directory }}"
+          key: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-${{ hashFiles('composer.lock') }}"
+          restore-keys: "php-${{ matrix.php-version }}-composer-${{ matrix.dependencies }}-"
+
+      - name: "Install locked dependencies from composer.lock"
+        if: "matrix.dependencies == 'locked'"
+        run: "composer install --no-interaction --no-progress --no-suggest"
+
+      - name: "Run tests with phpunit/phpunit"
+        run: "vendor/bin/phpunit --configuration=phpunit.xml.dist"

Makefile

@@ -0,0 +1,14 @@
+.PHONY: it
+it: tests ## Runs the tests target
+
+.PHONY: help
+help: ## Displays this list of targets with descriptions
+	@grep -E '^[a-zA-Z0-9_-]+:.*?## .*$$' $(MAKEFILE_LIST) | sort | awk 'BEGIN {FS = ":.*?## "}; {printf "\033[32m%-30s\033[0m %s\n", $$1, $$2}'
+
+.PHONY: tests
+tests: vendor ## Runs tests with phpunit/phpunit
+	vendor/bin/phpunit --configuration=phpunit.xml.dist
+
+vendor: composer.json composer.lock
+	composer validate --strict
+	composer install --no-interaction --no-progress --no-suggest

README.md

@@ -1,6 +1,6 @@
 # Tree
 
-[![Build Status](https://travis-ci.org/nicmart/Tree.svg?branch=master)](https://travis-ci.org/nicmart/Tree)
+[![Integrate](https://github.com/nicmart/Tree/workflows/Integrate/badge.svg?branch=master)](https://github.com/nicmart/Tree/actions)
 [![Latest Stable Version](https://poser.pugx.org/nicmart/tree/v/stable)](https://packagist.org/packages/nicmart/tree)
 [![Total Downloads](https://poser.pugx.org/nicmart/tree/downloads)](https://packagist.org/packages/nicmart/tree)
 [![License](https://poser.pugx.org/nicmart/tree/license)](https://packagist.org/packages/nicmart/tree)
@@ -161,7 +161,7 @@ Let's see how to build the following tree, where the nodes label are represents
         /|\
        D E F
       /|
-     G H   
+     G H
 ```
 
 And here is the code: