如何使用 Jest 和 react-testing-library 测试 react-dropzone？

Question

我想测试 React 组件中 react-dropzone 库中的 onDrop 方法。我正在使用 Jest，React 测试库。我正在创建模拟文件，并试图将这些文件放入输入中，但在 console.log 文件中仍然等于一个空数组。你有什么想法吗？

package.json

"typescript": "^3.9.7",
"@testing-library/jest-dom": "^5.11.4",
"@testing-library/react": "^11.0.4",
"@types/jest": "^26.0.13",
"jest": "^26.4.2",
"ts-jest": "^26.3.0",
"react-router-dom": "^5.1.2",
"react-dropzone": "^10.1.10",
"@types/react-dropzone": "4.2.0",

ModalImportFile.tsx

import React, { FC, useState } from "react";
import { Box, Button, Dialog, DialogContent, DialogTitle, Grid } from "@material-ui/core";
import { useDropzone } from "react-dropzone";
import AttachFileIcon from "@material-ui/icons/AttachFile";
import DeleteIcon from "@material-ui/icons/Delete";

interface Props {
    isOpen: boolean;
}

interface Events {
    onClose: () => void;
}

const ModalImportFile: FC<Props & Events> = props => {
    const { isOpen } = props as Props;
    const { onClose } = props as Events;

    const [files, setFiles] = useState<Array<File>>([]);

    const { getRootProps, getInputProps, open } = useDropzone({
        onDrop: (acceptedFiles: []) => {
            setFiles(
                acceptedFiles.map((file: File) =>
                    Object.assign(file, {
                        preview: URL.createObjectURL(file),
                    }),
                ),
            );
        },
        noClick: true,
        noKeyboard: true,
    });

    const getDragZoneContent = () => {
        if (files && files.length > 0)
            return (
                <Box border={1} borderRadius={5} borderColor={"#cecece"} p={2} mb={2}>
                    <Grid container alignItems="center" justify="space-between">
                        <Box color="text.primary">{files[0].name}</Box>
                        <Box ml={1} color="text.secondary">
                            <Button
                                startIcon={<DeleteIcon color="error" />}
                                onClick={() => {
                                    setFiles([]);
                                }}
                            />
                        </Box>
                    </Grid>
                </Box>
            );
        return (
            <Box border={1} borderRadius={5} borderColor={"#cecece"} p={2} mb={2} style={{ borderStyle: "dashed" }}>
                <Grid container alignItems="center">
                    <Box mr={1} color="text.secondary">
                        <AttachFileIcon />
                    </Box>
                    <Box color="text.secondary">
                        <Box onClick={open} component="span" marginLeft="5px">
                            Download
                        </Box>
                    </Box>
                </Grid>
            </Box>
        );
    };

    const closeHandler = () => {
        onClose();
        setFiles([]);
    };

    return (
        <Dialog open={isOpen} onClose={closeHandler}>
            <Box width={520}>
                <DialogTitle>Import</DialogTitle>
                <DialogContent>
                    <div data-testid="container" className="container">
                        <div data-testid="dropzone" {...getRootProps({ className: "dropzone" })}>
                            <input data-testid="drop-input" {...getInputProps()} />
                            {getDragZoneContent()}
                        </div>
                    </div>
                </DialogContent>
            </Box>
        </Dialog>
    );
};

export default ModalImportFile;

ModalImportFile.test.tsx

import React from "react";
import { render, screen, fireEvent } from "@testing-library/react";
import ModalImportFile from "../../components/task/elements/ModalImportFile";

const props = {
    isOpen: true,
    onClose: jest.fn(),
};

beforeEach(() => jest.clearAllMocks());

describe("<ModalImportFile/>", () => {
    it("should drop", async () => {
        render(<ModalImportFile {...props} />);

        const file = new File([JSON.stringify({ ping: true })], "ping.json", { type: "application/json" });
        const data = mockData([file]);

        function dispatchEvt(node: any, type: any, data: any) {
            const event = new Event(type, { bubbles: true });
            Object.assign(event, data);
            fireEvent(node, event);
        }

        function mockData(files: Array<File>) {
            return {
                dataTransfer: {
                    files,
                    items: files.map(file => ({
                        kind: "file",
                        type: file.type,
                        getAsFile: () => file,
                    })),
                    types: ["Files"],
                },
            };
        }
        const inputEl = screen.getByTestId("drop-input");
        dispatchEvt(inputEl, "dragenter", data);
    });
}

Answer 1

将fireEvent(node, event); 更改为fireEvent.drop(node, event); 怎么样。

Answer 2

根据 rokki 的回答 (https://stackoverflow.com/a/64643985/9405587)，我重写了测试组件以便于理解。

ModalImportFile.test.tsx

import React from "react";
import { render, screen, fireEvent } from "@testing-library/react";
import ModalImportFile from "../../components/task/elements/ModalImportFile";

const props = {
    isOpen: true,
    onClose: jest.fn(),
};

beforeEach(() => jest.clearAllMocks());

describe("<ModalImportFile/>", () => {
    it("should drop", async () => {
        render(<ModalImportFile {...props} />);
        window.URL.createObjectURL = jest.fn().mockImplementation(() => "url");
        const inputEl = screen.getByTestId("drop-input");
        const file = new File(["file"], "ping.json", {
            type: "application/json",
        });
        Object.defineProperty(inputEl, "files", {
            value: [file],
        });
        fireEvent.drop(inputEl);
        expect(await screen.findByText("ping.json")).toBeInTheDocument();
}