SQ: Automated tests, that will run on each OS in CI automatically

src/crystal/browser/__init__.py

@@ -571,9 +571,6 @@ def start_server(self) -> 'ProjectServer':
         """
         if self._project_server is None:
             self._log_drawer = LogDrawer(parent=self._frame)
-
-            # TODO: If the server couldn't be started (ex: due to the default port being in
-            #       use), report an appropriate error.
             self._project_server = ProjectServer(self.project, stdout=self._log_drawer.writer)
 
         return self._project_server

src/crystal/server.py

@@ -58,6 +58,7 @@ def __init__(self,
         self._verbosity = verbosity
         self._stdout = stdout
 
+        # Start server on port, looking for alternative open port if needed
         while True:
             try:
                 address = ('', port)

src/crystal/tests/index.py

@@ -117,7 +117,7 @@ def _run_tests(test_names: List[str]) -> bool:
         except SkipTest as e:
             result_for_test_func_id[test_func_id] = e
 
-            print('SKIP')
+            print(f'SKIP ({str(e)})')
         except Exception as e:
             result_for_test_func_id[test_func_id] = e
 

src/crystal/tests/test_server.py

@@ -2,15 +2,19 @@
 from copy import deepcopy
 from crystal.model import Project, Resource, ResourceRevision, RootResource
 from crystal import server
-from crystal.server import get_request_url
+from crystal.server import _DEFAULT_SERVER_PORT, get_request_url
 from crystal.tests.util.controls import click_button, TreeItem
 from crystal.tests.util.runner import bg_sleep
 from crystal.tests.util.server import (
-    assert_does_open_webbrowser_to, extracted_project, fetch_archive_url, WebPage,
+    assert_does_open_webbrowser_to, extracted_project, fetch_archive_url,
+    served_project, WebPage,
 )
+from crystal.tests.util.skip import skipTest
+from crystal.tests.util.tasks import wait_for_download_to_start_and_finish
 from crystal.tests.util.wait import DEFAULT_WAIT_PERIOD
-from crystal.tests.util.windows import MainWindow, OpenOrCreateDialog
+from crystal.tests.util.windows import AddUrlDialog, MainWindow, OpenOrCreateDialog
 from io import StringIO
+import socket
 import tempfile
 from typing import AsyncIterator, Callable, Optional, Tuple
 from unittest import skip
@@ -20,6 +24,60 @@
 #       in test_workflows.py. Write stubs for all such behaviors
 #       and link them to the covering test.
 
+# ------------------------------------------------------------------------------
+# Test: Start Server
+
+async def test_given_default_serving_port_in_use_when_start_serving_project_then_finds_alternate_port() -> None:
+    LOCALHOST = '127.0.0.1'
+
+    if _is_port_in_use(LOCALHOST, _DEFAULT_SERVER_PORT):
+        skipTest('_DEFAULT_SERVER_PORT is already in use outside of tests')
+    if _is_port_in_use(LOCALHOST, _DEFAULT_SERVER_PORT + 1):
+        skipTest('_DEFAULT_SERVER_PORT + 1 is already in use outside of tests')
+
+    with served_project('testdata_xkcd.crystalproj.zip', port=_DEFAULT_SERVER_PORT) as sp:
+        assert _is_port_in_use(LOCALHOST, _DEFAULT_SERVER_PORT)
+
+        # Define URLs
+        home_url = sp.get_request_url('https://xkcd.com/')
+
+        with tempfile.TemporaryDirectory(suffix='.crystalproj') as project_dirpath:
+            async with (await OpenOrCreateDialog.wait_for()).create(project_dirpath) as (mw, _):
+                project = Project._last_opened_project
+                assert project is not None
+
+                # Create a URL
+                if True:
+                    root_ti = TreeItem.GetRootItem(mw.entity_tree.window)
+                    assert root_ti is not None
+                    assert root_ti.GetFirstChild() is None  # no entities
+
+                    click_button(mw.add_url_button)
+                    aud = await AddUrlDialog.wait_for()
+
+                    aud.name_field.Value = 'Home'
+                    aud.url_field.Value = home_url
+                    await aud.ok()
+                    (home_ti,) = root_ti.Children
+
+                # Download the URL
+                home_ti.SelectItem()
+                await mw.click_download_button()
+                await wait_for_download_to_start_and_finish(mw.task_tree)
+
+                # Try to start second server, also on _DEFAULT_SERVER_PORT.
+                # Expect it to actually start on (_DEFAULT_SERVER_PORT + 1).
+                expected_port = _DEFAULT_SERVER_PORT + 1
+                home_ti.SelectItem()
+                with assert_does_open_webbrowser_to(get_request_url(home_url, expected_port)):
+                    click_button(mw.view_button)
+                assert _is_port_in_use(LOCALHOST, expected_port)
+
+                # Ensure can fetch the revision through the server
+                server_page = await fetch_archive_url(home_url, expected_port)
+                assert 200 == server_page.status
+
+
 # ------------------------------------------------------------------------------
 # Test: Header Inclusion & Exclusion
 
@@ -156,4 +214,19 @@ async def serve_and_fetch_xkcd_home_page(mw: MainWindow) -> Tuple[WebPage, str]:
     return (server_page, captured_stdout.getvalue())
 
 
+def _is_port_in_use(hostname: str, port: int) -> bool:
+    s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+    try:
+        try:
+            result = s.connect_ex((hostname, port))
+        except:
+            raise ValueError(f'socket.connect_ex({(hostname, port)}) failed')
+        if result == 0:
+            return True
+        else:
+            return False
+    finally:
+        s.close()
+
+
 # ------------------------------------------------------------------------------

src/crystal/tests/util/server.py

@@ -28,6 +28,7 @@
 def served_project(
         zipped_project_filename: str,
         *, fetch_date_of_resources_set_to: Optional[datetime.datetime]=None,
+        port: Optional[int]=None,
         ) -> Iterator[ProjectServer]:
     if fetch_date_of_resources_set_to is not None:
         if not datetime_is_aware(fetch_date_of_resources_set_to):
@@ -67,7 +68,7 @@ def fg_task() -> None:
 
             # Start server
             project_server = ProjectServer(project,
-                port=2798,  # CRYT on telephone keypad
+                port=(port or 2798),  # CRYT on telephone keypad
                 verbosity='indent',
             )
             yield project_server
@@ -114,12 +115,13 @@ async def is_url_not_in_archive(archive_url: str) -> bool:
 
 async def fetch_archive_url(
         archive_url: str,
+        port: Optional[int]=None,
         *, headers: Optional[Dict[str, str]]=None,
         timeout: Optional[float]=None,
         ) -> WebPage:
     if timeout is None:
         timeout = DEFAULT_WAIT_TIMEOUT
-    return await bg_fetch_url(get_request_url(archive_url), headers=headers, timeout=timeout)
+    return await bg_fetch_url(get_request_url(archive_url, port), headers=headers, timeout=timeout)
 
 
 class WebPage: