Function createToHaveNthReturnedWithMatcher

packages/expect/src/spyMatchers.ts:1099–1241

()

  };

const createToHaveNthReturnedWithMatcher = (): MatcherFunction<
  [number, unknown]
> =>
  function (received: any, nth, expected): SyncExpectationResult {
    const expectedArgument = 'n';
    const options: MatcherHintOptions = {
      expectedColor: (arg: string) => arg,
      isNot: this.isNot,
      promise: this.promise,
      secondArgument: 'expected',
    };
    ensureMock(received, 'toHaveNthReturnedWith', expectedArgument, options);

    if (!Number.isSafeInteger(nth) || nth < 1) {
      throw new Error(
        matcherErrorMessage(
          matcherHint(
            'toHaveNthReturnedWith',
            undefined,
            expectedArgument,
            options,
          ),
          `${expectedArgument} must be a positive integer`,
          printWithType(expectedArgument, nth, stringify),
        ),
      );
    }

    const receivedName = received.getMockName();
    const {calls, results} = received.mock;
    const length = results.length;
    const iNth = nth - 1;

    const pass = iNth < length && isEqualReturn(expected, results[iNth]);

    const message = pass
      ? () => {
          // Display preceding and following results,
          // in case assertions fails because index is off by one.
          const indexedResults: Array<IndexedResult> = [];
          if (iNth - 1 >= 0) {
            indexedResults.push([iNth - 1, results[iNth - 1]]);
          }
          indexedResults.push([iNth, results[iNth]]);
          if (iNth + 1 < length) {
            indexedResults.push([iNth + 1, results[iNth + 1]]);
          }

          return (
            // eslint-disable-next-line prefer-template
            matcherHint(
              'toHaveNthReturnedWith',
              receivedName,
              expectedArgument,
              options,
            ) +
            '\n\n' +
            `n: ${nth}\n` +