chore: add stack trace utilities and tests (#2371)

Author: dgozman

src/debug/sourceMap.ts

@@ -16,10 +16,7 @@
 
 import * as fs from 'fs';
 import * as util from 'util';
-import * as path from 'path';
-
-// NOTE: update this to point to playwright/lib when moving this file.
-const PLAYWRIGHT_LIB_PATH = path.normalize(path.join(__dirname, '..'));
+import { getCallerFilePath } from './stackTrace';
 
 type Position = {
   line: number;
@@ -118,28 +115,3 @@ function advancePosition(position: Position, delta: Position) {
     column: delta.column + (delta.line ? 0 : position.column),
   };
 }
-
-function getCallerFilePath(): string | null {
-  const error = new Error();
-  const stackFrames = (error.stack || '').split('\n').slice(1);
-  // Find first stackframe that doesn't point to PLAYWRIGHT_LIB_PATH.
-  for (let frame of stackFrames) {
-    frame = frame.trim();
-    if (!frame.startsWith('at '))
-      return null;
-    if (frame.endsWith(')')) {
-      const from = frame.indexOf('(');
-      frame = frame.substring(from + 1, frame.length - 1);
-    } else {
-      frame = frame.substring('at '.length);
-    }
-    const match = frame.match(/^(?:async )?(.*):(\d+):(\d+)$/);
-    if (!match)
-      return null;
-    const filePath = match[1];
-    if (filePath.startsWith(PLAYWRIGHT_LIB_PATH))
-      continue;
-    return filePath;
-  }
-  return null;
-}

src/debug/stackTrace.ts

@@ -0,0 +1,81 @@
+/**
+ * Copyright (c) Microsoft Corporation.
+ *
+ * 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.
+ */
+
+import * as path from 'path';
+
+// NOTE: update this to point to playwright/lib when moving this file.
+const PLAYWRIGHT_LIB_PATH = path.normalize(path.join(__dirname, '..'));
+
+type ParsedStackFrame = { filePath: string, functionName: string };
+
+function parseStackFrame(frame: string): ParsedStackFrame | null {
+  frame = frame.trim();
+  if (!frame.startsWith('at '))
+    return null;
+  frame = frame.substring('at '.length);
+  if (frame.startsWith('async '))
+    frame = frame.substring('async '.length);
+  let location: string;
+  let functionName: string;
+  if (frame.endsWith(')')) {
+    const from = frame.indexOf('(');
+    location = frame.substring(from + 1, frame.length - 1);
+    functionName = frame.substring(0, from).trim();
+  } else {
+    location = frame;
+    functionName = '';
+  }
+  const match = location.match(/^(?:async )?([^(]*):(\d+):(\d+)$/);
+  if (!match)
+    return null;
+  const filePath = match[1];
+  return { filePath, functionName };
+}
+
+export function getCallerFilePath(ignorePrefix = PLAYWRIGHT_LIB_PATH): string | null {
+  const error = new Error();
+  const stackFrames = (error.stack || '').split('\n').slice(1);
+  // Find first stackframe that doesn't point to ignorePrefix.
+  for (const frame of stackFrames) {
+    const parsed = parseStackFrame(frame);
+    if (!parsed)
+      return null;
+    if (parsed.filePath.startsWith(ignorePrefix) || parsed.filePath === __filename)
+      continue;
+    return parsed.filePath;
+  }
+  return null;
+}
+
+export function getCurrentApiCall(prefix = PLAYWRIGHT_LIB_PATH): string {
+  const error = new Error();
+  const stackFrames = (error.stack || '').split('\n').slice(1);
+  // Find last stackframe that points to prefix - that should be the api call.
+  let apiName: string = '';
+  for (const frame of stackFrames) {
+    const parsed = parseStackFrame(frame);
+    if (!parsed || (!parsed.filePath.startsWith(prefix) && parsed.filePath !== __filename))
+      break;
+    apiName = parsed.functionName;
+  }
+  const parts = apiName.split('.');
+  if (parts.length && parts[0].length) {
+    parts[0] = parts[0][0].toLowerCase() + parts[0].substring(1);
+    if (parts[0] === 'webKit')
+      parts[0] = 'webkit';
+  }
+  return parts.join('.');
+}

test/fixtures.spec.js

@@ -177,3 +177,20 @@ describe('Fixtures', function() {
     });
   });
 });
+
+describe('StackTrace', () => {
+  it('caller file path', async state => {
+    const stackTrace = require(path.join(state.playwrightPath, 'lib', 'debug', 'stackTrace'));
+    const callme = require('./fixtures/callback');
+    const filePath = callme(() => {
+      return stackTrace.getCallerFilePath(path.join(__dirname, 'fixtures') + path.sep);
+    });
+    expect(filePath).toBe(__filename);
+  });
+  it('api call', async state => {
+    const stackTrace = require(path.join(state.playwrightPath, 'lib', 'debug', 'stackTrace'));
+    const callme = require('./fixtures/callback');
+    const apiCall = callme(stackTrace.getCurrentApiCall.bind(stackTrace, path.join(__dirname, 'fixtures') + path.sep));
+    expect(apiCall).toBe('callme');
+  });
+});

test/fixtures/callback.js

@@ -0,0 +1,5 @@
+function callme(cb) {
+  return cb();
+}
+
+module.exports = callme;