Glamour comes with an extensive Morphic test suite.
You can check it here in the subclasses of GLMMorphicTest. The superclass also has a number of utility methods. The checking is done via excellent additions to Morphic (I believe by Sean).
GLMTextMorphicTest>>testAcceptKeyCanBeOverriden
| composite textMorph overriden |
overriden := false.
composite := GLMCompositePresentation new with: [ :a | a text act: [ :text | overriden := true ] on: $s entitled: 'Override'].
window := composite openOn: 4.
textMorph := self find: PluggableTextMorph in: window.
textMorph simulateClick.
self simulateKeyStroke: $s command.
self simulateKeyStroke: $s control.
self simulateKeyStroke: $s alt.
self assert: overriden.