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Add extra tests for various uncovered parts of the code - #64907
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Jake Bailey (jakebailey) wants to merge 14 commits into
Open
Jake Bailey (jakebailey) wants to merge 14 commits into
Jake Bailey (jakebailey) wants to merge 14 commits into
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Declaration emit serializes the types of JS expando assignments as if they were declared in the namespace synthesized for the host function. That scope decides whether existing annotations can be reused, so a `unique symbol` annotation is emitted as `symbol`. No existing test covered this.
A CommonJS module whose export assignment references `exports` is reported as circular (TS7022), because the type resolution pushed for the module.exports symbol is still on the stack. No existing test covered this.
TS2729 for a static property read before it is initialized is suppressed only when an earlier static block definitely assigns that property, as decided by flow analysis. An empty or non-assigning static block must not hide the error. No existing test covered this.
When a unique symbol used as a property name is reached through a re- export, the module in its fully qualified name is printed with a specifier relative to the containing file (`"./b".key`), not the module's absolute path. No existing test covered this.
Whether a class extends null is decided from its resolved base
constructor type, so `const N = null; class A extends N {}` counts under
strictNullChecks and its constructor does not require a super call
(TS2377). Existing tests only cover a literal `extends null`.
An ambient const or readonly initializer may be a literal enum reference, which is verified by checking that the expression's type is enum-like. Other property and element accesses, such as `declare const x = NS.v;`, must still report TS1254. No existing test covered this.
With importHelpers and emitDecoratorMetadata, TS2343 is reported when the tslib in use lacks __metadata, since the emitted code would call a helper that does not exist. No existing test covered the __metadata case.
Accessing a missing property on a PromiseLike or user-defined thenable reports TS2339, with the "Did you forget to use 'await'?" hint when the promised type has the property. Existing tests only cover the global Promise.
The contextual type of an await operand is a promise-like of the outer contextual type, with `Awaited<T>` unwrapped. That changes what a generic call in the operand infers: with a non-thenable constraint it infers `T` and reports that `T` is not assignable to `Awaited<T>`. No existing test covered this.
The elements of a spread tuple argument are checked like argument expressions, including instantiating a single generic signature in context, which changes the inferred return type of the call. No existing test covered this.
`0n` is definitely falsy, so `x && "a"` with `x: 0n | 1n` keeps `0n` in the result type. No existing test covered this.
Signature identity compares type predicates, so a redeclared variable whose function type differs only in its predicate reports TS2403. No existing test covered this.
When `a ?? b` or `a || b` initializes a binding pattern, the right operand is contextually typed by the pattern's implied type rather than the pattern itself, so literals in it are not widened. No existing test covered this.
`never` distributes to no types, so two `[k: never]` index signatures are not reported as duplicates (TS2374); only the invalid parameter type error (TS1268) is. No existing test covered this.
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The changes only add regression fixtures and matching baselines, with no identified blocking issues.
No open issues 🎉
What changed in this PR
Adds 14 compiler regression fixtures and corresponding baselines to capture previously uncovered behavior without changing compiler implementation.
Changes:
- Covers inference, symbol resolution, initialization, and diagnostic edge cases.
- Adds JavaScript module and declaration-emission coverage.
- Records expected types, symbols, diagnostics, and output, including configuration variants.
| File | Description |
|---|---|
tsc/testdata/tests/cases/compiler/uniqueSymbolPropertyNameFromReexportedModule.ts |
Tests reexported unique-symbol diagnostics. |
tsc/testdata/tests/cases/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks.ts |
Tests static initialization across field modes. |
tsc/testdata/tests/cases/compiler/spreadArgumentWithSingleGenericSignature.ts |
Tests generic inference through spread arguments. |
tsc/testdata/tests/cases/compiler/nullishAndLogicalOrRightOperandWithBindingPattern.ts |
Tests destructuring fallback inference. |
tsc/testdata/tests/cases/compiler/nonexistentPropertyOnThenable.ts |
Tests missing-property diagnostics on thenables. |
tsc/testdata/tests/cases/compiler/neverIndexSignatureNotDuplicate.ts |
Tests repeated never index signatures. |
tsc/testdata/tests/cases/compiler/moduleExportsSelfReferenceCircularity.ts |
Tests circular CommonJS export references. |
tsc/testdata/tests/cases/compiler/jsExpandoUniqueSymbolDeclarationEmit.ts |
Tests JavaScript expando declaration emission. |
tsc/testdata/tests/cases/compiler/importHelpersMissingMetadataHelper.ts |
Tests missing decorator metadata helpers. |
tsc/testdata/tests/cases/compiler/identicalSignaturesWithTypePredicates.ts |
Tests predicate signature identity. |
tsc/testdata/tests/cases/compiler/classExtendsNullValuedIdentifier.ts |
Tests null-valued bases across strictness modes. |
tsc/testdata/tests/cases/compiler/bigintZeroIsDefinitelyFalsy.ts |
Tests bigint-zero falsiness inference. |
tsc/testdata/tests/cases/compiler/awaitOperandContextualTypeUnwrapsAwaited.ts |
Tests contextual inference through await. |
tsc/testdata/tests/cases/compiler/ambientConstInitializerNonEnumReference.ts |
Tests ambient initializer restrictions. |
tsc/testdata/baselines/reference/compiler/uniqueSymbolPropertyNameFromReexportedModule.types |
Records reexported symbol types. |
tsc/testdata/baselines/reference/compiler/uniqueSymbolPropertyNameFromReexportedModule.symbols |
Records reexport symbol bindings. |
tsc/testdata/baselines/reference/compiler/uniqueSymbolPropertyNameFromReexportedModule.js |
Records reexport JavaScript output. |
tsc/testdata/baselines/reference/compiler/uniqueSymbolPropertyNameFromReexportedModule.errors.txt |
Records missing symbol-key diagnostics. |
tsc/testdata/baselines/reference/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks(usedefineforclassfields=true).types |
Records define-mode static-field types. |
tsc/testdata/baselines/reference/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks(usedefineforclassfields=true).symbols |
Records define-mode field bindings. |
tsc/testdata/baselines/reference/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks(usedefineforclassfields=true).js |
Records define-mode field emission. |
tsc/testdata/baselines/reference/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks(usedefineforclassfields=true).errors.txt |
Records define-mode initialization diagnostics. |
tsc/testdata/baselines/reference/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks(usedefineforclassfields=false).types |
Records assignment-mode static-field types. |
tsc/testdata/baselines/reference/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks(usedefineforclassfields=false).symbols |
Records assignment-mode field bindings. |
tsc/testdata/baselines/reference/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks(usedefineforclassfields=false).js |
Records assignment-mode field emission. |
tsc/testdata/baselines/reference/compiler/staticPropertyUsedBeforeInitializationWithStaticBlocks(usedefineforclassfields=false).errors.txt |
Records assignment-mode initialization diagnostics. |
tsc/testdata/baselines/reference/compiler/spreadArgumentWithSingleGenericSignature.types |
Records inferred spread-call result types. |
tsc/testdata/baselines/reference/compiler/spreadArgumentWithSingleGenericSignature.symbols |
Records generic spread-call bindings. |
tsc/testdata/baselines/reference/compiler/nullishAndLogicalOrRightOperandWithBindingPattern.types |
Records fallback literal-union inference. |
tsc/testdata/baselines/reference/compiler/nullishAndLogicalOrRightOperandWithBindingPattern.symbols |
Records destructuring symbol bindings. |
tsc/testdata/baselines/reference/compiler/nonexistentPropertyOnThenable.types |
Records thenable property-access types. |
tsc/testdata/baselines/reference/compiler/nonexistentPropertyOnThenable.symbols |
Records thenable symbol bindings. |
tsc/testdata/baselines/reference/compiler/nonexistentPropertyOnThenable.js |
Records thenable-access emission. |
tsc/testdata/baselines/reference/compiler/nonexistentPropertyOnThenable.errors.txt |
Records missing-property and await suggestions. |
tsc/testdata/baselines/reference/compiler/neverIndexSignatureNotDuplicate.types |
Records never index parameter types. |
tsc/testdata/baselines/reference/compiler/neverIndexSignatureNotDuplicate.symbols |
Records index-signature bindings. |
tsc/testdata/baselines/reference/compiler/neverIndexSignatureNotDuplicate.js |
Records interface erasure. |
tsc/testdata/baselines/reference/compiler/neverIndexSignatureNotDuplicate.errors.txt |
Records invalid index-type diagnostics. |
tsc/testdata/baselines/reference/compiler/moduleExportsSelfReferenceCircularity.types |
Records circular export inference. |
tsc/testdata/baselines/reference/compiler/moduleExportsSelfReferenceCircularity.symbols |
Records circular export bindings. |
tsc/testdata/baselines/reference/compiler/moduleExportsSelfReferenceCircularity.errors.txt |
Records export circularity diagnostics. |
tsc/testdata/baselines/reference/compiler/jsExpandoUniqueSymbolDeclarationEmit.types |
Records expando symbol widening. |
tsc/testdata/baselines/reference/compiler/jsExpandoUniqueSymbolDeclarationEmit.symbols |
Records expando property bindings. |
tsc/testdata/baselines/reference/compiler/jsExpandoUniqueSymbolDeclarationEmit.js |
Records emitted expando declarations. |
tsc/testdata/baselines/reference/compiler/importHelpersMissingMetadataHelper.types |
Records decorator fixture types. |
tsc/testdata/baselines/reference/compiler/importHelpersMissingMetadataHelper.symbols |
Records decorator and helper bindings. |
tsc/testdata/baselines/reference/compiler/importHelpersMissingMetadataHelper.js |
Records imported metadata helper calls. |
tsc/testdata/baselines/reference/compiler/importHelpersMissingMetadataHelper.errors.txt |
Records missing __metadata diagnostics. |
tsc/testdata/baselines/reference/compiler/identicalSignaturesWithTypePredicates.types |
Records predicate declaration types. |
tsc/testdata/baselines/reference/compiler/identicalSignaturesWithTypePredicates.symbols |
Records merged declaration bindings. |
tsc/testdata/baselines/reference/compiler/identicalSignaturesWithTypePredicates.errors.txt |
Records incompatible redeclaration diagnostics. |
tsc/testdata/baselines/reference/compiler/classExtendsNullValuedIdentifier(strict=true).types |
Records strict null-base inference. |
tsc/testdata/baselines/reference/compiler/classExtendsNullValuedIdentifier(strict=true).symbols |
Records strict null-base bindings. |
tsc/testdata/baselines/reference/compiler/classExtendsNullValuedIdentifier(strict=true).js |
Records strict null-base emission. |
tsc/testdata/baselines/reference/compiler/classExtendsNullValuedIdentifier(strict=true).errors.txt |
Records strict constructor diagnostics. |
tsc/testdata/baselines/reference/compiler/classExtendsNullValuedIdentifier(strict=false).types |
Records non-strict null-base inference. |
tsc/testdata/baselines/reference/compiler/classExtendsNullValuedIdentifier(strict=false).symbols |
Records non-strict null-base bindings. |
tsc/testdata/baselines/reference/compiler/classExtendsNullValuedIdentifier(strict=false).js |
Records non-strict null-base emission. |
tsc/testdata/baselines/reference/compiler/classExtendsNullValuedIdentifier(strict=false).errors.txt |
Records non-strict constructor diagnostics. |
tsc/testdata/baselines/reference/compiler/bigintZeroIsDefinitelyFalsy.types |
Records bigint logical-expression inference. |
tsc/testdata/baselines/reference/compiler/bigintZeroIsDefinitelyFalsy.symbols |
Records bigint fixture bindings. |
tsc/testdata/baselines/reference/compiler/awaitOperandContextualTypeUnwrapsAwaited.types |
Records contextual await inference. |
tsc/testdata/baselines/reference/compiler/awaitOperandContextualTypeUnwrapsAwaited.symbols |
Records await fixture bindings. |
tsc/testdata/baselines/reference/compiler/awaitOperandContextualTypeUnwrapsAwaited.errors.txt |
Records Awaited<T> assignment diagnostics. |
tsc/testdata/baselines/reference/compiler/ambientConstInitializerNonEnumReference.types |
Records ambient initializer types. |
tsc/testdata/baselines/reference/compiler/ambientConstInitializerNonEnumReference.symbols |
Records ambient reference bindings. |
tsc/testdata/baselines/reference/compiler/ambientConstInitializerNonEnumReference.errors.txt |
Records disallowed ambient initializer diagnostics. |
Review effort: Balanced
Jake Bailey (jakebailey)
enabled auto-merge
October 21, 2026 18:34
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Found these in a long session; none of this was being tested before.
It could be that some of this behavior is "not good", but we have no tests for them now.