Function toContain

packages/expect/src/matchers.ts:465–567

(received: ContainIterable | string, expected: unknown)

  },

  toContain(received: ContainIterable | string, expected: unknown) {
    const matcherName = 'toContain';
    const isNot = this.isNot;
    const options: MatcherHintOptions = {
      comment: 'indexOf',
      isNot,
      promise: this.promise,
    };

    if (received == null) {
      throw new Error(
        matcherErrorMessage(
          matcherHint(matcherName, undefined, undefined, options),
          `${RECEIVED_COLOR('received')} value must not be null nor undefined`,
          printWithType('Received', received, printReceived),
        ),
      );
    }

    if (typeof received === 'string') {
      const wrongTypeErrorMessage = `${EXPECTED_COLOR(
        'expected',
      )} value must be a string if ${RECEIVED_COLOR(
        'received',
      )} value is a string`;

      if (typeof expected !== 'string') {
        throw new TypeError(
          matcherErrorMessage(
            matcherHint(matcherName, received, String(expected), options),
            wrongTypeErrorMessage,
            // eslint-disable-next-line prefer-template
            printWithType('Expected', expected, printExpected) +
              '\n' +
              printWithType('Received', received, printReceived),
          ),
        );
      }

      const index = received.indexOf(String(expected));
      const pass = index !== -1;

      const message = () => {
        const labelExpected = `Expected ${
          typeof expected === 'string' ? 'substring' : 'value'
        }`;
        const labelReceived = 'Received string';
        const printLabel = getLabelPrinter(labelExpected, labelReceived);

        return (
          // eslint-disable-next-line prefer-template
          matcherHint(matcherName, undefined, undefined, options) +
          '\n\n' +
          `${printLabel(labelExpected)}${isNot ? 'not ' : ''}${printExpected(
            expected,
          )}\n` +
          `${printLabel(labelReceived)}${isNot ? '    ' : ''}${
            isNot