feat(logger): add pw:api logger (microsoft#386)

Author: pavelfeldman

client.py

@@ -18,14 +18,6 @@
 
 def main(playwright: Playwright) -> None:
     browser = playwright.chromium.launch(headless=False)
-    page = browser.new_page(viewport=0)
-    page.set_content(
-        "<button id=button onclick=\"window.open('http://webkit.org', '_blank')\">Click me</input>"
-    )
-
-    with page.expect_popup() as popup_info:
-        page.click("#button")
-    print(popup_info.value)
 
     print("Contexts in browser: %d" % len(browser.contexts))
     print("Creating context...")

playwright/_impl/_driver.py

@@ -18,6 +18,7 @@
 from pathlib import Path
 
 import playwright
+from playwright._impl._logger import init_logger
 
 
 def compute_driver_executable() -> Path:
@@ -37,3 +38,5 @@ def compute_driver_executable() -> Path:
         # RuntimeError: Cannot add child handler, the child watcher does not have a loop attached
         asyncio.get_event_loop()
         asyncio.get_child_watcher()
+
+init_logger()

playwright/_impl/_logger.py

@@ -0,0 +1,32 @@
+# 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 os
+import sys
+
+debug_enabled = os.environ.get("PWDEBUG") or (
+    "DEBUG" in os.environ and "pw:api" in os.environ["DEBUG"]
+)
+
+
+def init_logger() -> None:
+    if os.environ.get("PWDEBUG"):
+        os.environ["DEBUG"] = (
+            os.environ["DEBUG"] + ",pw:api" if "DEBUG" in os.environ else "pw:api"
+        )
+
+
+def log_api(text: str) -> None:
+    if debug_enabled:
+        print(f"  \033[1m\033[96mpw:api\033[0m {text}", file=sys.stderr)