Method asymmetricMatch

packages/expect/src/asymmetricMatchers.ts:256–289

(other: any)

  }

  asymmetricMatch(other: any) {
    // Ensures that the argument passed to the objectContaining method is an object
    if (typeof this.sample !== 'object') {
      throw new TypeError(
        `You must provide an object to ${this.toString()}, not '${typeof this
          .sample}'.`,
      );
    }

    // Ensures that the argument passed to the expect function is an object
    // This is necessary to avoid matching of non-object values
    // Arrays are a special type of object, but having a valid match with a standard object
    // does not make sense, hence we do a simple array check
    if (typeof other !== 'object' || Array.isArray(other)) {
      return false;
    }

    let result = true;

    const matcherContext = this.getMatcherContext();
    const objectKeys = getObjectKeys(this.sample);

    for (const key of objectKeys) {
      if (
        !hasProperty(other, key) ||
        !equals(this.sample[key], other[key], matcherContext.customTesters)
      ) {
        result = false;
        break;
      }
    }

    return this.inverse ? !result : result;
  }

  toString() {
    return `Object${this.inverse ? 'Not' : ''}Containing`;