@assertive-ts/core/src/lib/BooleanAssertion.ts

A type-safe fluent assertion library

import { Assertion } from "./Assertion";

import { AssertionError } from "assert";

/**
 * Encapsulates assertion methods applicable to values of type boolean
 */
export class BooleanAssertion extends Assertion<boolean> {

  public constructor(actual: boolean) {
    super(actual);
  }

  /**
   * Check if the value is `true`.
   *
   * @example
   * ```
   * expect(tsIsCool).toBeTrue();
   * ```
   *
   * @returns the assertion instance
   */
  public toBeTrue(): this {
    const error = new AssertionError({
      actual: this.actual,
      expected: true,
      message: "Expected value to be true",
    });
    const invertedError = new AssertionError({
      actual: this.actual,
      message: "Expected value to NOT be true",
    });

    return this.execute({
      assertWhen: this.actual === true,
      error,
      invertedError,
    });
  }

  /**
   * Check if the value is `false`.
   *
   * @example
   * ```
   * expect(pigsFly).toBeFalse();
   * ```
   *
   * @returns the assertion instance
   */
  public toBeFalse(): this {
    const error = new AssertionError({
      actual: this.actual,
      expected: false,
      message: "Expected value to be false",
    });
    const invertedError = new AssertionError({
      actual: this.actual,
      message: "Expected value to NOT be false",
    });

    return this.execute({
      assertWhen: this.actual === false,
      error,
      invertedError,
    });
  }
}