Use case

The WidgetTesterCallback typedef currently names its parameter widgetTester.

In practice, Flutter documentation, tutorials, and the vast majority of real-world
test code use the shorter and idiomatic name tester. Because IDEs use the
typedef’s parameter name for autocomplete, developers frequently need to manually
rename widgetTester to tester when writing widget tests.

This creates minor but repeated friction and inconsistency with established
Flutter conventions. There is no functional issue, but it negatively impacts
developer experience and API consistency.

Proposal

Rename the parameter in the WidgetTesterCallback typedef from widgetTester
to tester.

Current:

typedef WidgetTesterCallback = Future<void> Function(WidgetTester widgetTester);

Proposed:

typedef WidgetTesterCallback = Future<void> Function(WidgetTester tester);

This change is non-breaking, as parameter names in function typedefs are not part
of the public API contract.