38 lines
1.3 KiB
TypeScript
38 lines
1.3 KiB
TypeScript
// @lib: es2015
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// Tests fix for #20432, ensures Array.from accepts all valid inputs
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// Also tests for #19682
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interface A {
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a: string;
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}
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interface B {
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b: string;
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}
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const inputA: A[] = [];
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const inputB: B[] = [];
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const inputALike: ArrayLike<A> = { length: 0 };
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const inputARand = getEither(inputA, inputALike);
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const inputASet = new Set<A>();
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const result1: A[] = Array.from(inputA);
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const result2: A[] = Array.from(inputA.values());
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const result3: B[] = Array.from(inputA.values()); // expect error
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const result4: A[] = Array.from(inputB, ({ b }): A => ({ a: b }));
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const result5: A[] = Array.from(inputALike);
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const result6: B[] = Array.from(inputALike); // expect error
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const result7: B[] = Array.from(inputALike, ({ a }): B => ({ b: a }));
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const result8: A[] = Array.from(inputARand);
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const result9: B[] = Array.from(inputARand, ({ a }): B => ({ b: a }));
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const result10: A[] = Array.from(new Set<A>());
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const result11: B[] = Array.from(inputASet, ({ a }): B => ({ b: a }));
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// if this is written inline, the compiler seems to infer
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// the ?: as always taking the false branch, narrowing to ArrayLike<T>,
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// even when the type is written as : Iterable<T>|ArrayLike<T>
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function getEither<T> (in1: Iterable<T>, in2: ArrayLike<T>) {
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return Math.random() > 0.5 ? in1 : in2;
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}
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