Refactor handling of closed WebSocket connection (fixes #5)

This is refactored to be more similar to the way trio-websocket works:
the reader task should will catch ConnectionClosed and quietly exit. The
public APIs (i.e. session.execute()) will raise ConnectionClosed
instead. It's easier for the caller to catch an exception in a
foreground task than in a background task.

Author: mehaase

.gitignore

@@ -1,6 +1,7 @@
 .coverage
 *.egg-info
 .mypy_cache
+.vscode
 __pycache__
 dist
 test.png

Makefile

@@ -6,4 +6,4 @@ publish: test
 	twine upload dist/*
 
 test:
-	pytest test/ --cov=trio_cdp --cov-report=term-missing
+	pytest tests/ --cov=trio_cdp --cov-report=term-missing

README.md

@@ -15,7 +15,7 @@ multiplex commands, responses, and events over a single connection.
 The example demonstrates the salient features of the library.
 
 ```python
-async with open_cdp_connection(cdp_url) as conn:
+async with open_cdp(cdp_url) as conn:
     # Find the first available target (usually a browser tab).
     targets = await conn.execute(target.get_targets())
     target_id = targets[0].id
@@ -40,7 +40,7 @@ We'll go through this example bit by bit. First, it starts with a context
 manager:
 
 ```python
-async with open_cdp_connection(cdp_url) as conn:
+async with open_cdp(cdp_url) as conn:
 ```
 
 This context manager opens a connection to the browser when the block is entered
@@ -119,11 +119,11 @@ snippets.
 
 A more complete version of this example can be found in `examples/get_title.py`.
 There is also a screenshot example in `examples/screenshot.py`. The unit tests
-in `test/` also provide more examples.
+in `tests/` also provide more examples.
 
 To run the examples, you need a Chrome binary in your system. You can get one like this:
 
-#### FOR MAC
+## Running Examples on MacOS
 
 **Terminal 1**
 
@@ -132,7 +132,7 @@ This sets up the chrome browser in a specific version, and runs it in debug mode
 ```
 wget https://www.googleapis.com/download/storage/v1/b/chromium-browser-snapshots/o/Mac%2F678035%2Fchrome-mac.zip?generation=1563322360871926&alt=media
 unzip chrome-mac.zip && rm chrome-mac.zip
-./chrome-mac/Chromium.app/Contents/MacOS/Chromium --remote-debugging-port=9000 
+./chrome-mac/Chromium.app/Contents/MacOS/Chromium --remote-debugging-port=9000
 > DevTools listening on ws://127.0.0.1:9000/devtools/browser/<DEV_SESSION_GUID>
 ```
 
@@ -144,7 +144,7 @@ This runs the example browser automation script on the instantiated browser wind
 python examples/get_title.py ws://127.0.0.1:9000/devtools/browser/<DEV_SESSION_GUID> https://hyperiongray.com
 ```
 
-#### FOR LINUX
+## Running Examples on Linux
 
 **Terminal 1**
 
@@ -153,7 +153,7 @@ This sets up the chrome browser in a specific version, and runs it in debug mode
 ```
 wget https://storage.googleapis.com/chromium-browser-snapshots/Linux_x64/678025/chrome-linux.zip
 unzip chrome-linux.zip && rm chrome-linux.zip
-./chrome-linux/chrome --remote-debugging-port=9000 
+./chrome-linux/chrome --remote-debugging-port=9000
 > DevTools listening on ws://127.0.0.1:9000/devtools/browser/<DEV_SESSION_GUID>
 ```
 
@@ -165,7 +165,27 @@ This runs the example browser automation script on the instantiated browser wind
 python examples/get_title.py ws://127.0.0.1:9000/devtools/browser/<DEV_SESSION_GUID> https://hyperiongray.com
 ```
 
-<a href="https://www.hyperiongray.com/?pk_campaign=github&pk_kwd=trio-cdp"><img alt="define hyperion gray" width="500px" src="https://hyperiongray.s3.amazonaws.com/define-hg.svg"></a>
+## Changelog
+
+### 0.5.0
+
+* **Backwards Compability Break:** Rename `open_cdp_connection()` to `open_cdp()`.
+* Fix `ConnectionClosed` bug.
+
+### 0.4.0
+
+* Add support for passing in a nursery. (Supports usage in Jupyter notebook.)
+
+### 0.3.0
 
-id=E89C70427E6B7D2F56365B3E4C2268AA
-id=CC6E9EA42D2FFBABEDCC4E3282EF2A74
+* New APIs for enabling DOM events and Page events.
+
+### 0.2.0
+
+* Restructure event listeners.
+
+### 0.1.0
+
+* Initial version
+
+<a href="https://www.hyperiongray.com/?pk_campaign=github&pk_kwd=trio-cdp"><img alt="define hyperion gray" width="500px" src="https://hyperiongray.s3.amazonaws.com/define-hg.svg"></a>

examples/get_title.py

@@ -18,7 +18,7 @@
 
 from cdp import dom, page, target
 import trio
-from trio_cdp import open_cdp_connection
+from trio_cdp import open_cdp
 
 
 log_level = os.environ.get('LOG_LEVEL', 'info').upper()
@@ -29,7 +29,7 @@
 
 async def main():
     logger.info('Connecting to browser: %s', sys.argv[1])
-    async with open_cdp_connection(sys.argv[1]) as conn:
+    async with open_cdp(sys.argv[1]) as conn:
         logger.info('Listing targets')
         targets = await conn.execute(target.get_targets())
 

examples/screenshot.py

@@ -19,7 +19,7 @@
 
 from cdp import emulation, page, target
 import trio
-from trio_cdp import open_cdp_connection
+from trio_cdp import open_cdp
 
 
 log_level = os.environ.get('LOG_LEVEL', 'info').upper()
@@ -30,10 +30,10 @@
 
 async def main():
     logger.info('Connecting to browser: %s', sys.argv[1])
-    async with open_cdp_connection(sys.argv[1]) as conn:
+    async with open_cdp(sys.argv[1]) as conn:
         logger.info('Listing targets')
         targets = await conn.execute(target.get_targets())
-        
+
         for t in targets:
             if (t.type == 'page' and
                 not t.url.startswith('devtools://') and

examples/take_heap_snapshot.py

@@ -5,10 +5,10 @@
 the option `--remote-debugging-port=9000`. The URL that Chrome is listening on
 is displayed in the terminal after Chrome starts up.
 
-Then run this script with the Chrome URL as the first argument 
+Then run this script with the Chrome URL as the first argument
 
 $ python examples/take_heap_snapshot.py \
-    ws://localhost:9000/devtools/browser/facfb2295-... 
+    ws://localhost:9000/devtools/browser/facfb2295-...
 '''
 from datetime import datetime
 import logging
@@ -17,7 +17,7 @@
 
 from cdp import browser, dom, heap_profiler, page, target
 import trio
-from trio_cdp import open_cdp_connection
+from trio_cdp import open_cdp
 
 
 log_level = os.environ.get('LOG_LEVEL', 'info').upper()
@@ -52,7 +52,7 @@ async def progress_helper():
 
 async def main():
     cdp_uri = sys.argv[1]
-    async with open_cdp_connection(cdp_uri) as conn:
+    async with open_cdp(cdp_uri) as conn:
         logger.info('Connecting')
         targets = await conn.execute(target.get_targets())
         target_id = targets[0].target_id

tests/__init__.py

@@ -0,0 +1,21 @@
+from functools import wraps
+
+import pytest
+import trio
+
+
+class fail_after:
+    ''' This decorator fails if the runtime of the decorated function (as
+    measured by the Trio clock) exceeds the specified value. '''
+    def __init__(self, seconds):
+        self._seconds = seconds
+
+    def __call__(self, fn):
+        @wraps(fn)
+        async def wrapper(*args, **kwargs):
+            with trio.move_on_after(self._seconds) as cancel_scope:
+                await fn(*args, **kwargs)
+            if cancel_scope.cancelled_caught:
+                pytest.fail('Test runtime exceeded the maximum {} seconds'
+                    .format(self._seconds))
+        return wrapper

test/test_trio_cdp.py tests/test_trio_cdp.pytest/test_trio_cdp.py renamed to tests/test_trio_cdp.py

@@ -6,7 +6,8 @@
 import trio
 from trio_websocket import serve_websocket
 
-from trio_cdp import BrowserError, open_cdp_connection
+from . import fail_after
+from trio_cdp import BrowserError, open_cdp
 
 
 HOST = '127.0.0.1'
@@ -26,6 +27,7 @@ def test_browser_error():
         'This is extra data about the error'
 
 
+@fail_after(1)
 async def test_connection_execute(nursery):
     ''' Open a connection and execute a command on it. '''
     async def handler(request):
@@ -53,13 +55,13 @@ async def handler(request):
         except Exception:
             logging.exception('Server exception')
     server = await start_server(nursery, handler)
-
-    async with open_cdp_connection(server) as conn:
+    async with open_cdp(server) as conn:
         targets = await conn.execute(target.get_targets())
         assert len(targets) == 1
         assert isinstance(targets[0], target.TargetInfo)
 
 
+@fail_after(1)
 async def test_connection_invalid_json():
     ''' If the server sends invalid JSON, that exception is raised on the reader
     task, which crashes the entire connection. Therefore, the entire test needs
@@ -79,11 +81,12 @@ async def handler(request):
                     logging.exception('Server exception')
             server = await start_server(nursery, handler)
 
-            async with open_cdp_connection(server) as conn:
+            async with open_cdp(server) as conn:
                 targets = await conn.execute(target.get_targets())
     assert exc_info.value.code == -32700 # JSON parse error
 
 
+@fail_after(1)
 async def test_connection_browser_error(nursery):
     ''' If the browser sends an error with a valid command ID, then that error
     should be raised at the point where the command was executed. Compare to
@@ -110,13 +113,14 @@ async def handler(request):
             logging.exception('Server exception')
     server = await start_server(nursery, handler)
 
-    async with open_cdp_connection(server) as conn:
+    async with open_cdp(server) as conn:
         with pytest.raises(BrowserError) as exc_info:
             targets = await conn.execute(target.get_targets())
 
     assert exc_info.value.code == -32000
 
 
+@fail_after(1)
 async def test_session_execute(nursery):
     ''' Open a session and execute a command on it. '''
     async def handler(request):
@@ -159,14 +163,15 @@ async def handler(request):
             logging.exception('Server exception')
     server = await start_server(nursery, handler)
 
-    async with open_cdp_connection(server) as conn:
+    async with open_cdp(server) as conn:
         session = await conn.open_session(target.TargetID('target1'))
         assert session.session_id == 'session1'
         node_id = await session.execute(
             dom.query_selector(dom.NodeId(0),'p.foo'))
         assert node_id == 1
 
 
+@fail_after(1)
 async def test_wait_for_event(nursery):
     ''' The server sends 2 different events. The client is listening for a
     specific type of event and therefore only sees the 2nd one. '''
@@ -196,7 +201,7 @@ async def handler(request):
             logging.exception('Server exception')
     server = await start_server(nursery, handler)
 
-    async with open_cdp_connection(server) as conn:
+    async with open_cdp(server) as conn:
         async with conn.wait_for(page.LoadEventFired) as event:
             # In real code we would do something here to trigger a load event,
             # e.g. clicking a link.
@@ -205,6 +210,7 @@ async def handler(request):
         assert event.value.timestamp == 2
 
 
+@fail_after(1)
 async def test_listen_for_events(nursery):
     ''' The server sends 2 different events. The client is listening for a
     specific type of event and therefore only sees the 2nd one. '''
@@ -234,7 +240,7 @@ async def handler(request):
             logging.exception('Server exception')
     server = await start_server(nursery, handler)
 
-    async with open_cdp_connection(server) as conn:
+    async with open_cdp(server) as conn:
         n = 1
         async for event in conn.listen(page.LoadEventFired):
             assert isinstance(event, page.LoadEventFired)