Add existing tests to CI

.github/actions/run-godot-tests/action.yml

@@ -0,0 +1,16 @@
+name: Run Godot tests
+description: Run a test project on the target platform.
+
+inputs:
+  project-path:
+    default: "./tests"
+  run-script:
+    default: "./run.gd"
+
+runs:
+  using: "composite"
+  steps:
+    - name: Run the project script
+      shell: bash
+      run: |
+        godot --headless --path ${{ inputs.project-path }} --script ${{ inputs.run-script }} --verbose

.github/workflows/build-pull-request.yml

@@ -32,7 +32,12 @@ jobs:
     name: Compile and upload Android version
     uses: ./.github/workflows/extension-build-android.yml
 
-# Then, use the artifacts to test the example project.
+# Then, use the artifacts to do tests.
+
+  run-tests-project:
+    name: Run tests on target platforms
+    needs: [ build-linux, build-macos, build-windows, build-web, build-android ]
+    uses: ./.github/workflows/tests-run-project.yml
 
   export-example-project:
     name: Export the example project for target platforms

.github/workflows/build-release-tagged.yml

@@ -47,11 +47,18 @@ jobs:
     with:
       git-base-ref: ${{ github.ref }}
 
+# Then, use the artifacts to do tests.
+
+  run-tests-project:
+    name: Run tests on target platforms
+    needs: [ build-linux, build-macos, build-windows, build-web, build-android ]
+    uses: ./.github/workflows/tests-run-project.yml
+
 # Then, make a draft release for the tag.
 
   release-all:
     name: Make a draft GitHub Release for the tag
-    needs: [ build-linux, build-macos, build-windows, build-web, build-android ]
+    needs: [ run-tests-project ]
     runs-on: ubuntu-latest
     steps:
       - uses: actions/checkout@v4

.github/workflows/build-release-unstable.yml

@@ -46,18 +46,25 @@ jobs:
     with:
       git-base-ref: 'main'
 
+# Then, use the artifacts to do tests.
+
+  run-tests-project:
+    name: Run tests on target platforms
+    needs: [ build-linux, build-macos, build-windows, build-web, build-android ]
+    uses: ./.github/workflows/tests-run-project.yml
+
 # Then, use the artifacts to prepare the example project and publish the build.
 
   publish-all:
     name: Package and publish the extension
-    needs: [ build-linux, build-macos, build-windows, build-web, build-android ]
+    needs: [ run-tests-project ]
     uses: ./.github/workflows/extension-publish-all.yml
     with:
       release-version: 'latest-unstable'
 
   export-example-project:
     name: Export the example project for target platforms
-    needs: [ build-linux, build-macos, build-windows, build-web, build-android ]
+    needs: [ run-tests-project ]
     uses: ./.github/workflows/example-export-project.yml
     secrets: inherit
     with:

.github/workflows/tests-run-project.yml

@@ -0,0 +1,54 @@
+name: Run Tests
+
+on:
+  workflow_call:
+
+# Make sure jobs cannot overlap.
+concurrency:
+  group: test-${{ github.ref }}-project
+  cancel-in-progress: true
+
+env:
+  GODOT_VERSION: "4.3.0-stable"
+
+jobs:
+  export-publish:
+    strategy:
+      fail-fast: false
+      matrix:
+        include:
+          - platform: linux
+            arch: x86_64
+            preset: "Linux - x86_64"
+            runs-on: ubuntu-latest
+
+    name: Run the tests project (${{ matrix.preset }})
+    runs-on: ${{ matrix.runs-on }}
+    steps:
+      - uses: actions/checkout@v4
+
+      # Set up prerequisites.
+
+      - name: Install Godot ${{ env.GODOT_VERSION }}
+        uses: chickensoft-games/setup-godot@v2
+        with:
+          version: ${{ env.GODOT_VERSION }}
+          use-dotnet: false
+          include-templates: true
+
+      - name: Verify Godot
+        shell: bash
+        run: |
+          godot --version
+
+      - name: Download GDSiON artifacts
+        uses: actions/download-artifact@v4
+        with:
+          path: tests/bin
+          pattern: libgdsion-*
+          merge-multiple: true
+
+      # Run the tests.
+
+      - name: Run tests
+        uses: ./.github/actions/run-godot-tests