Add Gradle functional tests

Reference: https://guides.gradle.org/testing-gradle-plugins/

devtools/gradle/build.gradle

@@ -18,12 +18,6 @@ repositories {
     mavenCentral()
 }
 
-// Add a source set for the functional test suite
-sourceSets {
-    functionalTest {
-    }
-}
-
 dependencies {
     api gradleApi()
     implementation "io.quarkus:quarkus-bootstrap-core:${version}"
@@ -33,7 +27,7 @@ dependencies {
     implementation "io.quarkus:quarkus-development-mode:${version}"
     implementation "io.quarkus:quarkus-creator:${version}"
 
-    testImplementation 'org.assertj:assertj-core:3.13.2'
+    testImplementation 'org.assertj:assertj-core:3.14.0'
     testImplementation 'org.junit.jupiter:junit-jupiter-api:5.5.2'
     testImplementation 'org.junit.jupiter:junit-jupiter-params:5.5.2'
     testRuntimeOnly 'org.junit.jupiter:junit-jupiter-engine:5.5.2'
@@ -67,5 +61,26 @@ gradlePlugin {
     }
 }
 
-buildScan {
+// Add a source set for the functional test suite
+sourceSets {
+    functionalTest {
+    }
+}
+
+gradlePlugin.testSourceSets(sourceSets.functionalTest)
+configurations.functionalTestImplementation.extendsFrom(configurations.testImplementation)
+configurations.functionalTestRuntime.extendsFrom(configurations.testRuntimeOnly)
+
+// Add a task to run the functional tests
+task functionalTest(type: Test) {
+    description = "Runs functional tests"
+    group = "verification"
+    useJUnitPlatform()
+    testClassesDirs = sourceSets.functionalTest.output.classesDirs
+    classpath = sourceSets.functionalTest.runtimeClasspath
+}
+
+check {
+    // Run the functional tests as part of `check`
+    dependsOn(tasks.functionalTest)
 }

devtools/gradle/pom.xml

@@ -19,6 +19,8 @@
         <gradle.executable>./gradlew</gradle.executable>
         <gradle.task>build</gradle.task>
         <skip.gradle.build>false</skip.gradle.build>
+        <maven.install.skip>true</maven.install.skip>
+        <maven.deploy.skip>true</maven.deploy.skip>
     </properties>
 
     <dependencies>
@@ -77,6 +79,15 @@
                     </execution>
                 </executions>
             </plugin>
+            <!-- Do not deploy this project-->
+            <plugin>
+                <groupId>org.sonatype.plugins</groupId>
+                <artifactId>nexus-staging-maven-plugin</artifactId>
+                <version>${nexus-staging-maven-plugin.version}</version>
+                <configuration>
+                    <skipNexusStagingDeployMojo>true</skipNexusStagingDeployMojo>
+                </configuration>
+            </plugin>
         </plugins>
     </build>
     <profiles>

devtools/gradle/src/functionalTest/java/io/quarkus/gradle/QuarkusPluginFunctionalTest.java

@@ -0,0 +1,39 @@
+package io.quarkus.gradle;
+
+import java.io.File;
+import java.io.IOException;
+import java.util.HashMap;
+
+import io.quarkus.cli.commands.CreateProject;
+import io.quarkus.cli.commands.writer.FileProjectWriter;
+import io.quarkus.generators.BuildTool;
+import org.gradle.testkit.runner.BuildResult;
+import org.gradle.testkit.runner.GradleRunner;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+public class QuarkusPluginFunctionalTest {
+
+    @Test
+    public void canRunListExtensions(@TempDir File projectRoot) throws IOException {
+        assertThat(new CreateProject(new FileProjectWriter(projectRoot))
+                           .groupId("com.acme.foo")
+                           .artifactId("foo")
+                           .version("1.0.0-SNAPSHOT")
+                           .buildTool(BuildTool.GRADLE)
+                           .doCreateProject(new HashMap<>()))
+                .withFailMessage("Project was not created")
+                .isTrue();
+
+        BuildResult build = GradleRunner.create()
+                .forwardOutput()
+                .withPluginClasspath()
+                .withArguments("listExtensions")
+                .withProjectDir(projectRoot)
+                .build();
+
+        assertThat(build.getOutput()).contains("Quarkus - Core");
+    }
+}