Avoid running the same file multiple times (#856)

* avoid running the same file multiple times

* refactor `alreadySearchingParent` to make it a little easier to understand

lib/ava-files.js

@@ -197,9 +197,33 @@ function handlePaths(files, excludePatterns) {
 	// convert pinkie-promise to Bluebird promise
 	files = Promise.resolve(globby(files.concat(excludePatterns)));
 
+	var searchedParents = Object.create(null);
+	var foundFiles = Object.create(null);
+
+	function alreadySearchingParent(dir) {
+		if (searchedParents[dir]) {
+			return true;
+		}
+
+		var parentDir = path.dirname(dir);
+
+		if (parentDir === dir) {
+			// We have reached the root path.
+			return false;
+		}
+
+		return alreadySearchingParent(parentDir);
+	}
+
 	return files
 		.map(function (file) {
 			if (fs.statSync(file).isDirectory()) {
+				if (alreadySearchingParent(file)) {
+					return null;
+				}
+
+				searchedParents[file] = true;
+
 				var pattern = path.join(file, '**', '*.js');
 
 				if (process.platform === 'win32') {
@@ -216,10 +240,15 @@ function handlePaths(files, excludePatterns) {
 		})
 		.then(flatten)
 		.filter(function (file) {
-			return path.extname(file) === '.js' && path.basename(file)[0] !== '_';
+			return file && path.extname(file) === '.js' && path.basename(file)[0] !== '_';
 		})
 		.map(function (file) {
 			return path.resolve(file);
+		})
+		.filter(function (file) {
+			var alreadyFound = foundFiles[file];
+			foundFiles[file] = true;
+			return !alreadyFound;
 		});
 }
 

test/ava-files.js

@@ -95,3 +95,12 @@ test('sourceMatcher - providing negation patterns', function (t) {
 	t.false(matcher('foo/bar.js'));
 	t.end();
 });
+
+test('findFiles - does not return duplicates of the same file', function (t) {
+	var avaFiles = new AvaFiles(['**/ava-files/no-duplicates/**']);
+
+	avaFiles.findTestFiles().then(function (files) {
+		t.is(files.length, 2);
+		t.end();
+	});
+});

test/fixture/ava-files/no-duplicates/lib/bar.js

@@ -0,0 +1 @@
+// empty

test/fixture/ava-files/no-duplicates/lib/foo.js

@@ -0,0 +1 @@
+// empty