@brillout/libassert

Minimalistic & simple assertions for library authors.

Designed so that you can create all kinds of assertion types.

For example:

import { createError } from "@brillout/libassert";

export { assert, assertUsage, assertWarning };

const libName = "Awesome Library";

function assert(condition: unknown): asserts condition {
  if (condition) {
    return;
  }

  const prefix =
  `[${libName}][Internal Error] Something unexpected happened, `+
  `please open a GitHub issue.`;
  const err = createError({ prefix });

  throw err;
}

function assertUsage(condition: unknown, errorMessage: string): asserts condition {
  if (condition) {
    return;
  }

  const err = createError({
    prefix: `[${libName}][Wrong Usage]`,
    errorMessage,
  });

  throw err;
}

function assertWarning(condition: unknown, errorMessage: string): void {
  if (condition) {
    return;
  }

  const err = createError({
    prefix: `[${libName}][Warning]`,
    errorMessage,
  });

  console.warn(err);
}

The createError(errorMessage) is the same than new Error(${prefix} ${errorMessage}) except that:

• prefix and errorMessage are forbidden to contain new lines.
• The stack trace is complete but also cleaned to remove useless information.