这确实很烦人，尤其是因为升级Angular 版本后它往往会改变。我的快照现在也失败了，因为这个差异：-/。

-   __ngContext__={[Function LRootView]}
+   __ngContext__="0"

因此，查看jest配置后，快照序列化程序将从“jest-preset-angular”模块加载。
这里的相关插件是'jest-preset-angular/build/serializers/ng-snapshot'。现在，有两种方法可以摆脱__ngContext__。
1.用修改后的副本完全替换插件
在同一个目录中创建该文件的副本，并相应地对其进行修改（行https：//github.com/thymikee/jest-preset-angular/blob/40 b769 b8 eba 0 b82913827793 b6 d9 fe 06 d41808 d9/src/serializers/ng-snapshot.ts#L 69）：

const attributes = Object.keys(componentInstance).filter(key => key !== '__ngContext__');

调整配置：

snapshotSerializers: [
    'jest-preset-angular/build/serializers/no-ng-attributes',
    './custom-snapshot-serializer.ts',
    'jest-preset-angular/build/serializers/html-comment',
  ],

这种解决方案的缺点是，虽然只更改了一行，但您必须维护插件。
1.用 Package 程序替换插件（首选解决方案）
这只是为原始实现创建了一个 Package 器。其想法是在__ngContext__移动到插件链之前删除它。然而，原始插件的逻辑用于fixture序列化。

import type { ComponentRef, DebugNode, Type, ɵCssSelectorList } from '@angular/core';
import type { ComponentFixture } from '@angular/core/testing';
import type { Colors } from 'pretty-format';
import { test as origTest, print as origPrint } from 'jest-preset-angular/build/serializers/ng-snapshot';

/**
 * The follow interfaces are customized heavily inspired by @angular/core/core.d.ts
 */
interface ComponentDef {
  selectors: ɵCssSelectorList;
}
interface IvyComponentType extends Type<unknown> {
  ɵcmp: ComponentDef;
}
interface NgComponentRef extends ComponentRef<unknown> {
  componentType: IvyComponentType;
  _elDef: any; // eslint-disable-line @typescript-eslint/no-explicit-any
  _view: any; // eslint-disable-line @typescript-eslint/no-explicit-any
}
interface NgComponentFixture extends ComponentFixture<unknown> {
  componentRef: NgComponentRef;
  // eslint-disable-next-line @typescript-eslint/no-explicit-any
  componentInstance: Record<string, any>;
}

/**
 * The following types haven't been exported by jest so temporarily we copy typings from 'pretty-format'
 */
interface PluginOptions {
  edgeSpacing: string;
  min: boolean;
  spacing: string;
}
type Indent = (indentSpaces: string) => string;
type Printer = (elementToSerialize: unknown) => string;

export const print = (fixture: any, print: Printer, indent: Indent, opts: PluginOptions, colors: Colors): any => {
  const componentInstance = (fixture as NgComponentFixture).componentInstance;
  const instance = { ...componentInstance };
  delete instance.__ngContext__;
  const modifiedFixture = { ...fixture, componentInstance: { ...instance } };
  return origPrint(modifiedFixture, print, indent, opts, colors);
};

// eslint-disable-next-line @typescript-eslint/no-explicit-any, @typescript-eslint/explicit-module-boundary-types
export const test = (val: any): boolean => {
  return origTest(val);
};

配置的调整方式与之前相同。