Setup CI (#1)

.formatter.exs

@@ -1,4 +1,8 @@
 # Used by "mix format"
 [
-  inputs: ["{mix,.credo,.formatter}.exs", "{config,lib,test}/**/*.{ex,exs}"]
+  inputs: [
+    "{mix,.credo,.formatter}.exs",
+    ".github/github_workflows.ex",
+    "{config,lib,test}/**/*.{ex,exs}"
+  ]
 ]

.github/github_workflows.ex

@@ -0,0 +1,260 @@
+defmodule GithubWorkflows do
+  @moduledoc false
+
+  def get do
+    %{
+      "ci.yml" => ci_workflow()
+    }
+  end
+
+  defp ci_workflow do
+    [
+      [
+        name: "CI",
+        on: [
+          pull_request: [],
+          push: [
+            branches: ["main"]
+          ]
+        ],
+        jobs: [
+          compile: compile_job(),
+          credo: credo_job(),
+          deps_audit: deps_audit_job(),
+          dialyzer: dialyzer_job(),
+          format: format_job(),
+          hex_audit: hex_audit_job(),
+          prettier: prettier_job(),
+          test: test_job(),
+          unused_deps: unused_deps_job()
+        ]
+      ]
+    ]
+  end
+
+  defp compile_job do
+    elixir_job("Install deps and compile",
+      steps: [
+        [
+          name: "Install Elixir dependencies",
+          env: [MIX_ENV: "test"],
+          run: "mix deps.get"
+        ],
+        [
+          name: "Compile",
+          env: [MIX_ENV: "test"],
+          run: "mix compile"
+        ]
+      ]
+    )
+  end
+
+  defp credo_job do
+    elixir_job("Credo",
+      needs: :compile,
+      steps: [
+        [
+          name: "Check code style",
+          env: [MIX_ENV: "test"],
+          run: "mix credo --strict"
+        ]
+      ]
+    )
+  end
+
+  defp deps_audit_job do
+    elixir_job("Deps audit",
+      needs: :compile,
+      steps: [
+        [
+          name: "Check for vulnerable Mix dependencies",
+          env: [MIX_ENV: "test"],
+          run: "mix deps.audit"
+        ]
+      ]
+    )
+  end
+
+  defp dialyzer_job do
+    elixir_job("Dialyzer",
+      needs: :compile,
+      steps: [
+        [
+          name: "Restore PLT cache",
+          uses: "actions/cache@v3",
+          with:
+            [
+              path: "priv/plts"
+            ] ++ cache_opts(prefix: "plt-${{ matrix.versions.runner-image }}")
+        ],
+        [
+          name: "Create PLTs",
+          env: [MIX_ENV: "test"],
+          run: "mix dialyzer --plt"
+        ],
+        [
+          name: "Run dialyzer",
+          env: [MIX_ENV: "test"],
+          run: "mix dialyzer --format short 2>&1"
+        ]
+      ]
+    )
+  end
+
+  defp elixir_job(name, opts) do
+    needs = Keyword.get(opts, :needs)
+    steps = Keyword.get(opts, :steps, [])
+
+    job = [
+      name: name,
+      "runs-on": "${{ matrix.versions.runner-image }}",
+      strategy: [
+        "fail-fast": false,
+        matrix: [
+          versions: [
+            %{
+              elixir: "1.11",
+              otp: "21.3",
+              "runner-image": "ubuntu-20.04"
+            },
+            %{
+              elixir: "1.16",
+              otp: "26.2",
+              "runner-image": "ubuntu-latest"
+            }
+          ]
+        ]
+      ],
+      steps:
+        [
+          checkout_step(),
+          [
+            name: "Set up Elixir",
+            uses: "erlef/setup-beam@v1",
+            with: [
+              "elixir-version": "${{ matrix.versions.elixir }}",
+              "otp-version": "${{ matrix.versions.otp }}"
+            ]
+          ],
+          [
+            uses: "actions/cache@v3",
+            with:
+              [
+                path: ~S"""
+                _build
+                deps
+                """
+              ] ++ cache_opts(prefix: "mix-${{ matrix.versions.runner-image }}")
+          ]
+        ] ++ steps
+    ]
+
+    if needs do
+      Keyword.put(job, :needs, needs)
+    else
+      job
+    end
+  end
+
+  defp format_job do
+    elixir_job("Format",
+      needs: :compile,
+      steps: [
+        [
+          name: "Check Elixir formatting",
+          env: [MIX_ENV: "test"],
+          run: "mix format --check-formatted"
+        ]
+      ]
+    )
+  end
+
+  defp hex_audit_job do
+    elixir_job("Hex audit",
+      needs: :compile,
+      steps: [
+        [
+          name: "Check for retired Hex packages",
+          env: [MIX_ENV: "test"],
+          run: "mix hex.audit"
+        ]
+      ]
+    )
+  end
+
+  defp prettier_job do
+    [
+      name: "Check formatting using Prettier",
+      "runs-on": "ubuntu-latest",
+      steps: [
+        checkout_step(),
+        [
+          name: "Restore npm cache",
+          uses: "actions/cache@v3",
+          id: "npm-cache",
+          with: [
+            path: "~/.npm",
+            key: "npm-ubuntu-latest"
+          ]
+        ],
+        [
+          name: "Install Prettier",
+          if: "steps.npm-cache.outputs.cache-hit != 'true'",
+          run: "npm i -g prettier"
+        ],
+        [
+          name: "Run Prettier",
+          run: "npx prettier -c ."
+        ]
+      ]
+    ]
+  end
+
+  defp test_job do
+    elixir_job("Test",
+      needs: :compile,
+      steps: [
+        [
+          name: "Run tests",
+          env: [
+            MIX_ENV: "test",
+            MUX_CREDENTIALS_EMAIL: "${{ secrets.MUX_CREDENTIALS_EMAIL }}",
+            MUX_CREDENTIALS_PASSWORD: "${{ secrets.MUX_CREDENTIALS_PASSWORD }}"
+          ],
+          run: "mix test --cover"
+        ]
+      ]
+    )
+  end
+
+  defp unused_deps_job do
+    elixir_job("Check unused deps",
+      needs: :compile,
+      steps: [
+        [
+          name: "Check for unused Mix dependencies",
+          env: [MIX_ENV: "test"],
+          run: "mix deps.unlock --check-unused"
+        ]
+      ]
+    )
+  end
+
+  defp checkout_step do
+    [
+      name: "Checkout",
+      uses: "actions/checkout@v4"
+    ]
+  end
+
+  defp cache_opts(opts) do
+    prefix = Keyword.get(opts, :prefix)
+
+    [
+      key: "#{prefix}-${{ matrix.versions.otp }}-${{ matrix.versions.elixir }}-${{ github.sha }}",
+      "restore-keys": ~s"""
+      #{prefix}-
+      """
+    ]
+  end
+end