Add GitHub Actions workflow file (#2)

* Add GitHub Actions workflow file

* Remove warning when Explorer is not available

.github/workflows/ci.yml

@@ -0,0 +1,58 @@
+name: "ReqCh CI"
+
+on:
+  push:
+    branches:
+      - main
+  pull_request:
+  workflow_dispatch:
+
+env:
+  MIX_ENV: test
+
+jobs:
+  test:
+    services:
+      clickhouse:
+        image: clickhouse/clickhouse-server:24.10
+        ports:
+          - "8123:8123"
+          - "9000:9000"
+
+    strategy:
+      matrix:
+        include:
+          - otp_version: "25.3"
+            elixir_version: "1.14"
+
+          - otp_version: "27.1.2"
+            elixir_version: "1.17"
+
+    runs-on: ubuntu-latest
+    name: test
+    steps:
+      - uses: actions/checkout@v4
+
+      - uses: erlef/setup-beam@v1
+        with:
+          otp-version: ${{ matrix.otp_version }}
+          elixir-version: ${{ matrix.elixir_version }}
+
+      - run: mix deps.get
+      - run: mix deps.compile
+      - name: Run tests
+        run: mix test --warnings-as-errors
+
+      - name: Compile once again but without optional deps
+        run: mix compile --force --warnings-as-errors --no-optional-deps
+
+  format:
+    runs-on: ubuntu-latest
+    name: mix format
+    steps:
+      - uses: actions/checkout@v4
+      - uses: erlef/setup-beam@v1
+        with:
+          otp-version: "27.1.2"
+          elixir-version: "1.17"
+      - run: mix format --check-formatted

lib/req_ch.ex

@@ -154,14 +154,22 @@ defmodule ReqCh do
     is_parquet_response = response.headers["x-clickhouse-format"] == ["Parquet"]
 
     if want_explorer_df and is_parquet_response do
-      Req.Request.halt(request, %{
-        response
-        | body: Explorer.DataFrame.load_parquet!(response.body)
-      })
+      Req.Request.halt(request, %{response | body: load_parquet(response.body)})
     else
       pair
     end
   end
 
   defp handle_clickhouse_result(request_response), do: request_response
+
+  if Code.ensure_loaded?(Explorer) do
+    defp load_parquet(body) do
+      Explorer.DataFrame.load_parquet!(body)
+    end
+  else
+    defp load_parquet(_body) do
+      raise ArgumentError,
+            "format: :explorer - you need to install Explorer as a dependency in order to use this format"
+    end
+  end
 end