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我正在使用 TypeScript 编写一个 React 应用程序。我将 material-ui 用于我的组件，将 react-testing-library 用于我的单元测试。

我正在为 material-ui 的 Grid 组件编写一个包装器，这样我总是有一个容器。

import Grid from "@material-ui/core/Grid";
import withStyles, { WithStyles } from "@material-ui/core/styles/withStyles";
import React, { PureComponent } from "react";
import styles from "./styles";

export interface OwnProps {
  className?: string;
}

export interface Props extends WithStyles<typeof styles>, OwnProps {}

export interface DefaultProps {
  className: string;
}

export class GridContainer extends PureComponent<Props & DefaultProps> {
  static defaultProps: DefaultProps = {
    className: ""
  };

  render() {
    const { classes, children, className, ...rest } = this.props;
    return (
      <Grid
        data-testid="grid-container"
        container={true}
        {...rest}
        className={classes.grid + " " + className}
      >
        {children}
      </Grid>
    );
  }
}

export default withStyles(styles)(GridContainer);

我想编写一个测试来检查它的孩子是否正确呈现。这是我写的：

import "jest-dom/extend-expect";
import React from "react";
import { cleanup, render } from "react-testing-library";
import GridContainer, { OwnProps } from "./GridContainer";
afterEach(cleanup);

const createTestProps = (props?: object): OwnProps => ({
  ...props
});

describe("GridContainer", () => {
  const props = createTestProps();
  const { getByTestId } = render(
    <GridContainer {...props}>
      <div data-testid="child" />
    </GridContainer>
  );
  const container = getByTestId("grid-container");
  describe("rendering", () => {
    test("it renders it's children", () => {
      expect(container.children.length).toBe(1);
      expect(getByTestId("child")).toBeDefined();
    });
  });
});

问题是测试的第一部分，我检查孩子通过的长度。但是expect(getByTestId("child")).toBeDefined();失败了：

● GridContainer › rendering › it renders it's children

    Unable to find an element by: [data-testid="child"]

    <body />

      24 |     test("it renders it's children", () => {
      25 |       expect(container.children.length).toBe(1);
    > 26 |       expect(getByTestId("child")).toBeDefined();
         |              ^
      27 |     });
      28 |   });
      29 | });

      at getElementError (node_modules/dom-testing-library/dist/query-helpers.js:30:10)
      at getAllByTestId (node_modules/dom-testing-library/dist/queries.js:231:45)
      at firstResultOrNull (node_modules/dom-testing-library/dist/query-helpers.js:38:30)
      at getByTestId (node_modules/dom-testing-library/dist/queries.js:241:42)
      at Object.getByTestId (src/components/Grid/GridContainer/GridContainer.test.tsx:26:14)

不能给渲染函数中的元素提供 data-testid 吗？我如何测试孩子们是否正确渲染？

编辑 这是调试的输出：

● Console

    console.log node_modules/react-testing-library/dist/index.js:57
      <body>
        <div>
          <div
            class="MuiGrid-container-2 GridContainer-grid-1 "
            data-testid="grid-container"
          >
            <div
              data-testid="child"
            />
          </div>
        </div>
      </body>
4

1 回答 1

2

问题是您在describe块中渲染一次。这可能不像你想的那样工作。Jest 会提前运行describe不在test（或其他类似的 jest 函数）中的块中的代码。beforeEach通常，您永远不希望在describe块内但在test（或其他笑话函数）之外的任何代码。

您可以在 a 中渲染组件，也可以beforeEach在每个测试中调用渲染辅助函数。

我用上述方法在这里分叉了你的沙箱，现在两个测试都通过了：https ://codesandbox.io/s/v3wk1vlx3l

于 2018-11-10T00:31:48.923 回答