Make sure executable ends with .exe under Windows

This commit fixes the executable name when the plugin is running
under Windows: `nativeRun` would fail because it doesn't append
the `.exe` extension to the file name.

Fixes #198

.github/workflows/windows.yml

@@ -0,0 +1,34 @@
+name: Windows Minimal Tests
+
+on:
+  push:
+    paths:
+      - 'native-gradle-plugin/**'
+      - 'samples/**'
+      - 'common/**'
+  pull_request:
+    paths:
+      - 'native-gradle-plugin/**'
+      - 'samples/**'
+      - 'common/**'
+  workflow_dispatch:
+
+jobs:
+  build:
+    runs-on: windows-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: graalvm/setup-graalvm@v1
+        with:
+          version: 'dev'
+          java-version: '11'
+          components: 'native-image'
+          github-token: ${{ secrets.GITHUB_TOKEN }}
+      - name: Check and test the Gradle plugin
+        run: ./gradlew.bat :native-gradle-plugin:functionalTest --no-daemon
+      - name: Tests results
+        if: always()
+        uses: actions/upload-artifact@v2
+        with:
+          name: functional-tests-results-${{ matrix.gradle-version }}
+          path: native-maven-plugin/build/reports/tests/

native-gradle-plugin/src/main/java/org/graalvm/buildtools/gradle/tasks/BuildNativeImageTask.java

@@ -73,6 +73,7 @@
 import java.nio.file.Paths;
 import java.util.List;
 
+import static org.graalvm.buildtools.utils.SharedConstants.EXECUTABLE_EXTENSION;
 import static org.graalvm.buildtools.utils.SharedConstants.GU_EXE;
 import static org.graalvm.buildtools.utils.SharedConstants.NATIVE_IMAGE_EXE;
 
@@ -107,7 +108,7 @@ protected Provider<String> getGraalVMHome() {
 
     @Internal
     public Provider<String> getExecutableName() {
-        return getOptions().flatMap(NativeImageOptions::getImageName);
+        return getOptions().flatMap(options -> options.getImageName().map(name -> name + EXECUTABLE_EXTENSION));
     }
 
     @Internal