fix - Use project's jacoco agent when it's available (#1723)

src/utils/coverageUtils.ts

@@ -1,10 +1,29 @@
 // Copyright (c) Microsoft Corporation. All rights reserved.
 // Licensed under the MIT license.
 
+import { DebugConfiguration } from 'vscode';
 import { extensionContext } from '../extension';
 import * as path from 'path';
 
-export function getJacocoAgentPath(): string {
+const jacocoAgentRegex: RegExp = /org\.jacoco\.agent-\d+\.\d+\.\d+-runtime\.jar$/;
+
+export function getJacocoAgentPath(debugConfiguration: DebugConfiguration): string {
+    if (debugConfiguration.classPaths) {
+        for (const classPath of debugConfiguration.classPaths) {
+            if (jacocoAgentRegex.test(classPath)) {
+                return classPath;
+            }
+        }
+    }
+
+    if (debugConfiguration.modulePaths) {
+        for (const modulePath of debugConfiguration.modulePaths) {
+            if (jacocoAgentRegex.test(modulePath)) {
+                return modulePath;
+            }
+        }
+    }
+
     return extensionContext.asAbsolutePath('server/jacocoagent.jar');
 }
 

src/utils/launchUtils.ts

@@ -83,7 +83,7 @@ export async function resolveLaunchConfigurationForRunner(runner: BaseRunner, te
     }
 
     if (testContext.profile?.kind === TestRunProfileKind.Coverage) {
-        let agentArg: string = `-javaagent:${getJacocoAgentPath()}=destfile=${getJacocoDataFilePath(launchArguments.projectName)}`;
+        let agentArg: string = `-javaagent:${getJacocoAgentPath(debugConfiguration)}=destfile=${getJacocoDataFilePath(launchArguments.projectName)}`;
         if (config?.coverage?.appendResult === false) {
             agentArg += ',append=false';
         }

test/suite/coverageUtils.test.ts

@@ -0,0 +1,28 @@
+// Copyright (c) Microsoft Corporation. All rights reserved.
+// Licensed under the MIT license.
+
+'use strict';
+
+import * as assert from 'assert';
+import * as coverageUtils from '../../src/utils/coverageUtils';
+import { DebugConfiguration } from 'vscode';
+
+// tslint:disable: only-arrow-functions
+// tslint:disable: no-object-literal-type-assertion
+suite('CoverageUtils Tests', () => {
+
+    test('Use project jacoco agent if it is available', async () => {
+        const debugConfiguration: DebugConfiguration = {
+            name: 'Tests',
+            type: 'java',
+            request: 'launch',
+            classPaths: [
+                '/foo/bar/org.jacoco.agent-1.2.3-runtime.jar',
+            ]
+        }
+        assert.strictEqual(
+            coverageUtils.getJacocoAgentPath(debugConfiguration),
+            '/foo/bar/org.jacoco.agent-1.2.3-runtime.jar'
+        );
+    });
+});