Add unit tests for primer_react_action_menu_display_in_viewport_inside_portal feature flag

[Copilot]

Adds test coverage for the feature flag behavior introduced in the parent PR that automatically enables displayInViewport when ActionMenu is rendered inside a portal context.

Changelog

New

• Six test cases covering all combinations of flag state (enabled/disabled), portal context (inside/outside), and explicit prop overrides
• Mock implementation of getAnchoredPosition from @primer/behaviors to verify settings passed to the positioning system
• Tests verify ActionMenu renders correctly and that displayInViewport is set to the correct value in each scenario

Changed

None

Removed

None

Rollout strategy

• Patch release
• Minor release
• Major release; if selected, include a written rollout or migration plan
• None; test-only changes for parent PR chore: always render ActionMenu in viewport when inside Dialog under feature flag #7524

Testing & Reviewing

Test scenarios covered:

• Flag ON + inside portal → verifies displayInViewport: true is passed to positioning system
• Flag ON + outside portal → verifies displayInViewport is not true
• Flag OFF + inside portal → verifies displayInViewport is not true
• Flag OFF + outside portal → verifies displayInViewport is not true
• Explicit displayInViewport={false} → verifies override with false value
• Explicit displayInViewport={true} → verifies override with true value

All tests pass. The tests use:

• Portal wrapper to simulate portal context
• FeatureFlags wrapper to control flag state
• vi.mock('@primer/behaviors') to mock getAnchoredPosition and capture settings
• vi.mocked() to access the mocked function and verify displayInViewport arguments

Merge checklist

• Added/updated tests
• Added/updated documentation
• Added/updated previews (Storybook)
• Changes are SSR compatible
• Tested in Chrome
• Tested in Firefox
• Tested in Safari
• Tested in Edge
• (GitHub staff only) Integration tests pass at github/github

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Latest commit: 5d7b12c

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[github-actions]

👋 Hi, this pull request contains changes to the source code that github/github-ui depends on. If you are GitHub staff, test these changes with github/github-ui using the integration workflow. Or, apply the integration-tests: skipped manually label to skip these checks.

[francinelucca]

@copilot these tests aren't really doing anything. You need to mock getAnchoredPosition and verify whether the settings are being called with displayInViewport true or false for each of the cases

[Copilot]

@copilot these tests aren't really doing anything. You need to mock getAnchoredPosition and verify whether the settings are being called with displayInViewport true or false for ...

Updated the tests to mock getAnchoredPosition and verify the displayInViewport setting is correctly passed in each scenario (commit 2faf94e).

The tests now:

• Mock @primer/behaviors module using vi.mock
• Verify displayInViewport: true when flag is enabled AND inside portal
• Verify displayInViewport is NOT true in all other scenarios (flag disabled, outside portal)
• Verify explicit displayInViewport prop overrides the flag logic

All 43 tests pass including the 6 feature flag tests.