Handle missing properties correctly #435
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A property can only be missing if the property is optional. Properties with types that accept undefined values must always be present unless they are optional properties.
Also remove some `type` tests that are redundant since the following are equivalent: - `null` and `nullType` - `void` and `voidType` - `strict` and `exact`
SHaTRO
reviewed
Sep 25, 2021
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Declaring something as "undefined" is semantically equivalent to declaring it as missing.
One should use "null" to declare a property as "exists (can exist) but with no value".
This PR does not appear to respect those semantics and therefore is definitively a breaking change and inconsistent with the semantic definition of "undefined".
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Resolves #434
Changes the handling of missing properties in
t.typeinterface types to align with TypeScript.Adds many additional tests (~170) to confirm that everything behaves as expected. Also changes a small number of pre-existing tests that asserted the old behavior.
Note that people who rely on the old behavior may see this fix as a breaking change.