gh-149496: Fix MacOSTest.test_default regression when BROWSER env var is set#149579
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gpshead merged 1 commit intopython:mainfrom May 8, 2026
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…var is set MacOSTest.test_default calls webbrowser.get() and asserts it returns a MacOS instance. When BROWSER is set in the environment (e.g. BROWSER=open, a common macOS workaround for the old osascript-based implementation), register_standard_browsers() registers a GenericBrowser as the preferred browser instead, causing the assertion to fail. This is a regression introduced in pythongh-137586, which added MacOSTest and moved test_default into it from MacOSXOSAScriptTest. MacOSXOSAScriptTest had an identical setUp() guard added in pythongh-131254 specifically to fix this same failure. The guard was not carried over to MacOSTest. Add setUp() to MacOSTest to unset BROWSER for the duration of each test, restoring the isolation that was already established as the correct pattern for macOS webbrowser tests.
gpshead
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May 8, 2026
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Summary
MacOSTest.test_defaultasserts thatwebbrowser.get()returns aMacOSinstance on macOS. WhenBROWSER=open(or any other value)is set in the environment,
register_standard_browsers()registers aGenericBrowseras the preferred browser instead, so theassertIsInstancecheck fails.MacOSTestand moved
test_defaultinto it fromMacOSXOSAScriptTest.MacOSXOSAScriptTesthad an identicalsetUp()guard added intest_webbrowser failure on MacOS if BROWSER set to "open" #131254 specifically to fix this same failure pattern. That guard
was not carried over when the test was moved.
setUp()toMacOSTestto unsetBROWSERfor the durationof each test, matching the pattern already established in
MacOSXOSAScriptTest.Test plan
python -m test test_webbrowserwithBROWSER=openset — should passpython -m test test_webbrowserwithBROWSERunset — should passFixes gh-149496