[extra-02] check code quality and test in ci

Configure github actions to execute:
1. Code analysis with format/credo/dialyzer
2. Test with code coverage

.github/workflows/ci.yml

@@ -0,0 +1,128 @@
+---
+# based on:
+# 1. https://dev.to/mnishiguchi/basic-github-actions-setup-for-phoenix-apps-m3g
+# 2. https://www.jonathanyeong.com/garden/how-to-setup-ci-with-phoenix-github-actions/
+name: CI
+
+on:
+  push:
+    branches: [main]
+  pull_request:
+    brances: [main]
+
+env:
+  MIX_ENV: test
+
+jobs:
+  dependencies:
+    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        elixir: ['1.12.1']
+        otp: ['24.0.2']
+    steps:
+      - name: cancel previous execution
+        uses: styfle/cancel-workflow-action@0.9.0
+        with:
+          access_token: ${{ github.token }}
+      - name: checkout repo
+        uses: actions/checkout@v2
+      - name: setup erlang/elixir
+        uses: erlef/setup-beam@v1
+        with:
+          elixir-version: ${{ matrix.elixir }}
+          otp-version: ${{ matrix.otp }}
+      - name: fecth cached dependencies
+        uses: actions/cache@v2
+        id: mix-cache
+        with:
+          path: |
+            deps
+            _build
+            priv/plts
+          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('mix.lock') }}
+      - name: install dependencies
+        if: steps.mix-cache.outputs.cache-hit != 'true'
+        run: |
+          mkdir -p priv/plts
+          mix local.rebar --force
+          mix local.hex --force
+          mix deps.get
+          mix deps.compile
+          mix dialyzer --plt
+  static-code-analysis:
+    needs: dependencies
+    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        elixir: ['1.12.1']
+        otp: ['24.0.2']
+    steps:
+      - name: cancel previous execution
+        uses: styfle/cancel-workflow-action@0.9.0
+        with:
+          access_token: ${{ github.token }}
+      - name: checkout repo
+        uses: actions/checkout@v2
+      - name: setup erlang/elixir
+        uses: erlef/setup-beam@v1
+        with:
+          elixir-version: ${{ matrix.elixir }}
+          otp-version: ${{ matrix.otp }}
+      - name: fecth cached dependencies
+        uses: actions/cache@v2
+        id: mix-cache
+        with:
+          path: |
+            deps
+            _build
+            priv/plts
+          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('mix.lock') }}
+      - run: mix format --check-formatted
+      - run: mix credo --strict --format flycheck
+      - run: mix dialyzer --no-check --quiet --ignore-exit-status --format short
+  test:
+    needs: dependencies
+    runs-on: ubuntu-20.04
+    strategy:
+      matrix:
+        elixir: ['1.12.1']
+        otp: ['24.0.2']
+    services:
+      db:
+        image: 'postgres:13.3-alpine'
+        ports:
+          - '5432:5432'
+        env:
+          POSTGRES_USER: postgres
+          POSTGRES_PASSWORD: postgres
+        options: >-
+          --health-cmd pg_isready
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+    steps:
+      - name: cancel previous execution
+        uses: styfle/cancel-workflow-action@0.9.0
+        with:
+          access_token: ${{ github.token }}
+      - name: checkout repo
+        uses: actions/checkout@v2
+      - name: setup erlang/elixir
+        uses: erlef/setup-beam@v1
+        with:
+          elixir-version: ${{ matrix.elixir }}
+          otp-version: ${{ matrix.otp }}
+      - name: fecth cached dependencies
+        uses: actions/cache@v2
+        id: mix-cache
+        with:
+          path: |
+            deps
+            _build
+            priv/plts
+          key: ${{ runner.os }}-${{ matrix.otp }}-${{ matrix.elixir }}-${{ hashFiles('mix.lock') }}
+      - run: mix test --cover --trace --slowest 10
+        env:
+          POSTGRES_USER: postgres
+          POSTGRES_PASS: postgres