[testing] Pass tests files to mocha as dashed args

This avoids mocha accidentally picking up the test files itself.

Bug: 333423685
Change-Id: I5c15c619f07c913a5ababb8b7b9dd24ed195eb09
Reviewed-on: https://chromium-review.googlesource.com/c/devtools/devtools-frontend/+/5591052
Commit-Queue: Simon Zünd <szuend@chromium.org>
Auto-Submit: Philip Pfaffe <pfaffe@chromium.org>
Reviewed-by: Simon Zünd <szuend@chromium.org>

test/conductor/test_config.ts

@@ -62,8 +62,20 @@ function mochaGrep(): Config['mochaGrep'] {
   return grep;
 }
 
+function getTestsFromOptions() {
+  const tests = options['tests'];
+  if (Array.isArray(tests)) {
+    return tests;
+  }
+
+  if (typeof tests === 'string') {
+    return [tests];
+  }
+  return [];
+}
+
 export const TestConfig: Config = {
-  tests: options['tests'],
+  tests: getTestsFromOptions(),
   artifactsDir: options['artifacts-dir'] || SOURCE_ROOT,
   chromeBinary: options['chrome-binary'] ?? defaultChromePath(),
   serverType: ServerType.HostedMode,

test/run.ts

@@ -92,11 +92,11 @@ class Tests {
         pathToCheck => isContainedInDirectory(path.buildPath, pathToCheck.buildPath));
   }
 
-  protected run(tests: PathPair[], args: string[]) {
+  protected run(tests: PathPair[], args: string[], positionalTestArgs = true) {
     const argumentsForNode = [
       ...args,
       '--',
-      ...tests.map(t => t.buildPath),
+      ...tests.map(t => positionalTestArgs ? t.buildPath : `--tests=${t.buildPath}`),
       ...forwardOptions(),
     ];
     if (options['debug-driver']) {
@@ -112,11 +112,16 @@ class Tests {
 
 class MochaTests extends Tests {
   override run(tests: PathPair[]) {
-    return super.run(tests, [
-      path.join(SOURCE_ROOT, 'node_modules', 'mocha', 'bin', 'mocha'),
-      '--config',
-      path.join(this.suite.buildPath, 'mocharc.js'),
-    ]);
+    return super.run(
+        tests,
+        [
+          path.join(SOURCE_ROOT, 'node_modules', 'mocha', 'bin', 'mocha'),
+          '--config',
+          path.join(this.suite.buildPath, 'mocharc.js'),
+        ],
+        /* positionalTestArgs= */ false,  // Mocha interprets positional arguments as test files itself. Work around
+                                          // that by passing the tests as dashed args instead.
+    );
   }
 }