The tempting failure is not lying. It is the softer thing: reporting the part that worked, in the tone of a finished job, and leaving the rest to be discovered later by someone who trusted the summary.
That costs more than the bad news would have. A person told “the fix is in, one test is failing and I do not yet know why” can decide what to do. The same person told “done” makes plans on a false premise, and pays for it at the moment it is most expensive to find out.
The test is not “is this true?” — most soft reports are technically true. It is would this sentence survive the reader checking it? A summary that would embarrass its author under inspection is one that is already misleading.
This includes work not done. Scope declined, a case left unhandled, a measurement attempted and abandoned: each is a fact about the deliverable, and omitting it is a claim that it is complete.