feat(expect): support expect.addSnapshotSerialize() api

expect/_snapshot_serializer.ts

@@ -0,0 +1,15 @@
+// Copyright 2018-2024 the Deno authors. All rights reserved. MIT license.
+
+import type { SnapshotPlugin } from "./_types.ts";
+
+let INTERNAL_PLUGINS: SnapshotPlugin[] = [
+  // Todo: support serialize plugin
+];
+
+export function addSerializer(plugin: SnapshotPlugin): void {
+  INTERNAL_PLUGINS = [plugin, ...INTERNAL_PLUGINS];
+}
+
+export function getSerializer() {
+  return INTERNAL_PLUGINS;
+}

expect/_types.ts

@@ -110,3 +110,78 @@ export type EqualOptions = {
 export interface EqualOptionUtil extends MatcherContext {
   strictCheck?: boolean;
 }
+
+export interface Colors {
+  comment: { close: string; open: string };
+  content: { close: string; open: string };
+  prop: { close: string; open: string };
+  tag: { close: string; open: string };
+  value: { close: string; open: string };
+}
+type Indent = (arg0: string) => string;
+type Print = (arg0: unknown) => string;
+
+export type Refs = Array<unknown>;
+
+export type CompareKeys = ((a: string, b: string) => number) | null | undefined;
+
+export interface Config {
+  callToJSON: boolean;
+  compareKeys: CompareKeys;
+  colors: Colors;
+  escapeRegex: boolean;
+  escapeString: boolean;
+  indent: string;
+  maxDepth: number;
+  maxWidth: number;
+  min: boolean;
+  plugins: SnapshotPlugin;
+  printBasicPrototype: boolean;
+  printFunctionName: boolean;
+  spacingInner: string;
+  spacingOuter: string;
+}
+
+export type Printer = (
+  val: unknown,
+  config: Config,
+  indentation: string,
+  depth: number,
+  refs: Refs,
+  hasCalledToJSON?: boolean,
+) => string;
+
+interface PluginOptions {
+  edgeSpacing: string;
+  min: boolean;
+  spacing: string;
+}
+
+type Test = (arg0: any) => boolean;
+
+export interface NewSnapshotPlugin {
+  serialize: (
+    val: any,
+    config: Config,
+    indentation: string,
+    depth: number,
+    refs: Refs,
+    printer: Printer,
+  ) => string;
+  test: Test;
+}
+
+export interface OldSnapshotPlugin {
+  print: (
+    val: unknown,
+    print: Print,
+    indent: Indent,
+    options: PluginOptions,
+    colors: Colors,
+  ) => string;
+  test: Test;
+}
+
+export type SnapshotPlugin = NewSnapshotPlugin | OldSnapshotPlugin;
+
+export type SnapshotPlugins = Array<SnapshotPlugin>;

expect/expect.ts

@@ -50,6 +50,7 @@ import {
   toStrictEqual,
   toThrow,
 } from "./_matchers.ts";
+import { addSerializer } from "./_snapshot_serializer.ts";
 import { isPromiseLike } from "./_utils.ts";
 import {
   any,
@@ -197,6 +198,7 @@ export function expect(value: unknown, customMessage?: string): Expected {
 }
 
 expect.addEqualityTesters = addCustomEqualityTesters;
+expect.addSnapshotSerializers = addSerializer;
 expect.extend = setExtendMatchers;
 
 expect.anything = anything;