new QuarkusJavaLauncher which takes JAVA_HOME into account (fixes #2012)

This should fix the test failure on environments where the
wrong `java` is on the `PATH`, such as in Azure; for details, see
microsoft/azure-pipelines-tasks#10103.

devtools/gradle-it-run/src/test/java/io/quarkus/gradle/it/GradleRunIntegrationTest.java

@@ -17,14 +17,9 @@
 
 import static io.restassured.RestAssured.given;
 import static org.hamcrest.CoreMatchers.is;
-import static org.junit.jupiter.api.Assertions.assertTrue;
 
 import org.junit.jupiter.api.Test;
 
-import ch.vorburger.exec.ManagedProcess;
-import ch.vorburger.exec.ManagedProcessBuilder;
-import ch.vorburger.exec.ManagedProcessException;
-
 /**
  * Integration Test which runs the sample app built by Gradle.
  *
@@ -33,26 +28,14 @@
 public class GradleRunIntegrationTest {
     // do not rename this to *IT because we want it to run on regular mvn test without requiring failsafe
 
-    private static final String EXPECTED_CONSOLE_MESSAGE = "Listening on: http";
-    private static final int MAX_WAIT_IN_MS = 13000;
-
     @Test
-    public void testHelloEndpoint() throws ManagedProcessException {
-        ManagedProcess process = new ManagedProcessBuilder("java")
-                .addArgument("-jar").addArgument("../gradle-it/build/gradle-it-runner.jar").build();
-        assertTrue(
-                process.startAndWaitForConsoleMessageMaxMs(EXPECTED_CONSOLE_MESSAGE, MAX_WAIT_IN_MS),
-                EXPECTED_CONSOLE_MESSAGE + " did not appear?!");
-
-        try {
+    public void testHelloEndpoint() throws Exception {
+        try (QuarkusJavaLauncher process = new QuarkusJavaLauncher("../gradle-it/build/gradle-it-runner.jar")) {
             given()
                     .when().get("/hello")
                     .then()
                     .statusCode(200)
                     .body(is("hello"));
-
-        } finally {
-            process.destroy();
         }
     }
 }

devtools/gradle-it-run/src/test/java/io/quarkus/gradle/it/QuarkusJavaLauncher.java

@@ -0,0 +1,82 @@
+/*
+ * Copyright 2019 Red Hat, Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package io.quarkus.gradle.it;
+
+import ch.vorburger.exec.ManagedProcess;
+import ch.vorburger.exec.ManagedProcessBuilder;
+
+/**
+ * Launch Quarkus JARs as external processes for integration testing.
+ *
+ * @author <a href="mailto:mike@vorburger.ch">Michael Vorburger.ch</a>
+ */
+public class QuarkusJavaLauncher implements AutoCloseable {
+
+    // TODO Move this test utility class somewhere common so that it can be used by other ITs
+
+    public static final int MAX_CONSOLE_LINES = 1000;
+    private static final String EXPECTED_CONSOLE_MESSAGE = "Listening on: http";
+    private static final int MAX_WAIT_IN_MS = 13000;
+
+    private final ManagedProcess process;
+
+    // Use throws Exception instead of ManagedProcessException so that users don't depend on types from the internally used library
+    public QuarkusJavaLauncher(String pathToQuarkusJAR) throws Exception {
+        process = new ManagedProcessBuilder(getJavaExecutable())
+                .addArgument("-jar").addArgument(pathToQuarkusJAR)
+                .setConsoleBufferMaxLines(MAX_CONSOLE_LINES).build();
+
+        if (!process.startAndWaitForConsoleMessageMaxMs(EXPECTED_CONSOLE_MESSAGE, MAX_WAIT_IN_MS)) {
+            process.destroy();
+            throw new IllegalStateException(
+                    EXPECTED_CONSOLE_MESSAGE + " did not appear (after waiting " + MAX_WAIT_IN_MS / 1000 + "s)");
+        }
+    }
+
+    protected String getJavaExecutable() {
+        String javaHome = System.getenv("JAVA_HOME");
+        if (javaHome == null) {
+            return "java";
+        } else {
+            // required due to https://github.com/quarkusio/quarkus/issues/2012
+            return javaHome + "/bin/java";
+        }
+    }
+
+    /**
+     * Obtain the output which the process printed to (both) STDOUT and STDERR.
+     *
+     * It includes up to maximum {@link #MAX_CONSOLE_LINES} lines; earlier output is lost.
+     *
+     * This is useful for <a href="https://github.com/quarkusio/quarkus/issues/2005">tests who want to assert on the (non)
+     * appearance of particular log messages.
+     *
+     * @return new line separated multi-line output text
+     */
+    public String getOutput() {
+        return process.getConsole();
+    }
+
+    /**
+     * Stop the external JVM.
+     */
+    @Override
+    public void close() throws Exception {
+        if (process.isAlive()) {
+            process.destroy();
+        }
+    }
+}