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58 lines
2.3 KiB
58 lines
2.3 KiB
export enum AssertionMode {
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SKIP = "SKIP",
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LOG = "LOG",
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THROW = "THROW",
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}
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/** Configurations for the different assertion modes. */
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export namespace AssertionConfig {
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/** The types of the assertion configurations. */
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export type Type = typeof Skip|typeof Throw|ReturnType<typeof Log>
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/** An assertion configuration suitable for production, that skips assertions without evaluating them. */
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export const Skip = {mode: AssertionMode.SKIP} as const
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/** An assertion configuration suitable for testing, that throws an exception when an assertion fails. */
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export const Throw = {mode: AssertionMode.THROW} as const
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/** An assertion configuration suitable for debugging, that logs an exception when an assertion fails but allows the program to continue. */
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export function Log(logger: (message?: unknown, ...params: unknown[]) => void) {
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return {mode: AssertionMode.LOG, logger} as const
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}
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}
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/** Assertion class for test-only checks on preconditions and postconditions. */
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export class Assertions {
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config: AssertionConfig.Type = AssertionConfig.Skip
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/** General assert method. Checks that the condition is true. */
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check<T>(value: T, condition: (value: T) => boolean, message: (value: T) => string): T {
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if (this.config.mode === AssertionMode.SKIP) {
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return value
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}
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const result = condition(value)
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if (result) {
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return value
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}
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const err = Error(message(value))
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if (this.config.mode === AssertionMode.THROW) {
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throw err
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} else {
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// All we can do is stand by and watch in horror...
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this.config.logger(err)
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return value
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}
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}
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/** Checks that the value is an integer. */
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checkInteger(value: number, message: (value: number) => string): number {
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return this.check(value, Number.isSafeInteger, message)
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}
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/** Checks that the value is an integer and either positive or zero. */
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checkPositiveIntegerOrZero(value: number, message: (value: number) => string): number {
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return this.check(value, (value) => {
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return Number.isSafeInteger(value) && value >= 0
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}, message)
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}
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}
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/** Global assertion object for use by other modules. */
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export const assertion = new Assertions(); |