bcquality/microsoft/knowledge/testing/asserterror-needs-expectederror-and-code.md

bc-version	domain	keywords	technologies	countries	application-area
all	testing	asserterror expectederror expectederrorcode negative-test error-code	al	w1	all

Pin asserterror to a specific error with ExpectedError and ExpectedErrorCode

Description

asserterror passes when the guarded statement raises any error at all. That is too permissive for a negative test: a typo, a missing setup record, or a permission failure all raise errors, so a bare asserterror can go green while never exercising the rule it claims to verify — false confidence that the validation works. Constrain it. Assert.ExpectedError(text) checks the message of the error that was actually raised, and Assert.ExpectedErrorCode(code) checks its error code. Together they assert that the specific failure occurred, turning "something went wrong" into "the right thing went wrong for the right reason".

Best Practice

Follow every asserterror with a verification of the error it expects: assert the action raises, then Assert.ExpectedError with the message — or a stable substring of it — and, where the code is known, Assert.ExpectedErrorCode (for example 'TestField' for a mandatory-field check). Prefer matching on a code or an invariant fragment over the full localized sentence so the test survives caption changes without going blind to the wrong error.

See sample: asserterror-needs-expectederror-and-code.good.al.

Anti Pattern

asserterror DoInvalid(); with nothing after it. The test asserts only that the call failed somehow; swap the validation for a different bug and the test still passes, certifying a guard that may no longer fire. A negative test that cannot tell one error from another verifies almost nothing.

See sample: asserterror-needs-expectederror-and-code.bad.al.