unit testing example for tree entry form

__tests__/TreeEntryForm.test.tsx

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+/**
+ * @jest-environment jsdom
+ */
+
+import React from "react";
+import "@testing-library/jest-dom";
+import { render, screen, fireEvent, waitFor } from "@testing-library/react";
+import TreeEntryForm from "@/app/newTreeForm/page";
+import userEvent from "@testing-library/user-event";
+
+describe("TreeEntryForm", () => {
+  it("renders the form correctly", () => {
+    render(<TreeEntryForm />);
+
+    // getting elements
+    expect(screen.getByPlaceholderText("Tree Name")).toBeInTheDocument();
+    expect(screen.getByPlaceholderText("Species")).toBeInTheDocument();
+    expect(screen.getByPlaceholderText("Location")).toBeInTheDocument();
+    expect(screen.getByPlaceholderText("Description")).toBeInTheDocument();
+    expect(screen.getByRole("combobox")).toBeInTheDocument();
+    expect(screen.getByRole("button", { name: /submit/i })).toBeInTheDocument();
+  });
+
+  it("updates form fields when user types", async () => {
+    render(<TreeEntryForm />);
+
+    // getting elements
+    const treeNameInput = screen.getByPlaceholderText("Tree Name") as HTMLInputElement;
+    const speciesInput = screen.getByPlaceholderText("Species") as HTMLInputElement;
+    const locationInput = screen.getByPlaceholderText("Location") as HTMLInputElement;
+    const descriptionInput = screen.getByPlaceholderText("Description") as HTMLTextAreaElement;
+
+    // simulating user input
+    await userEvent.type(treeNameInput, "Oak");
+    await userEvent.type(speciesInput, "Quercus robur");
+    await userEvent.type(locationInput, "Central Park");
+    await userEvent.type(descriptionInput, "A majestic oak tree.");
+
+    // checking that the inputted values are what are displayed
+    expect(treeNameInput.value).toBe("Oak");
+    expect(speciesInput.value).toBe("Quercus robur");
+    expect(locationInput.value).toBe("Central Park");
+    expect(descriptionInput.value).toBe("A majestic oak tree.");
+  });
+
+  it("updates the file input when a file is selected", async () => {
+    render(<TreeEntryForm />);
+
+    const fileInput = screen.getByRole("button", { name: /submit/i }).previousSibling as HTMLInputElement;
+    const file = new File(["tree"], "tree.png", { type: "image/png" });
+
+    fireEvent.change(fileInput, { target: { files: [file] } });
+
+    await waitFor(() => {
+      expect(fileInput.files).toHaveLength(1);
+      expect(fileInput.files![0].name).toBe("tree.png");
+    });
+  });
+
+  it("submits the form and displays the submitted data", async () => {
+    render(<TreeEntryForm />);
+
+    // get html elements
+    const treeNameInput = screen.getByPlaceholderText("Tree Name") as HTMLInputElement;
+    const speciesInput = screen.getByPlaceholderText("Species") as HTMLInputElement;
+    const locationInput = screen.getByPlaceholderText("Location") as HTMLInputElement;
+    const descriptionInput = screen.getByPlaceholderText("Description") as HTMLTextAreaElement;
+    const conditionSelect = screen.getByRole("combobox") as HTMLSelectElement;
+    const fileInput = screen.getByRole("button", { name: /submit/i }).previousSibling as HTMLInputElement;
+    const submitButton = screen.getByRole("button", { name: /submit/i });
+
+    // simulating user input
+    await userEvent.type(treeNameInput, "Oak");
+    await userEvent.type(speciesInput, "Quercus robur");
+    await userEvent.type(locationInput, "Central Park");
+    await userEvent.type(descriptionInput, "A majestic oak tree.");
+    await userEvent.selectOptions(conditionSelect, "Healthy");
+
+    const file = new File(["tree"], "tree.png", { type: "image/png" });
+    await userEvent.upload(fileInput, file);
+
+    await userEvent.click(submitButton);
+
+    // awaiting display of submitted data after clicking submit
+    await waitFor(() => {
+      expect(screen.getByText("Submitted Data")).toBeInTheDocument();
+      expect(screen.getByText("Tree Name: Oak")).toBeInTheDocument();
+      expect(screen.getByText("Species: Quercus robur")).toBeInTheDocument();
+      expect(screen.getByText("Location: Central Park")).toBeInTheDocument();
+      expect(screen.getByText("Description: A majestic oak tree.")).toBeInTheDocument();
+      expect(screen.getByText("Condition: Healthy")).toBeInTheDocument();
+      expect(screen.getByText("Photo: tree.png")).toBeInTheDocument();
+    });
+  });
+});

jest.config.ts

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+/**
+ * For a detailed explanation regarding each configuration property, visit:
+ * https://jestjs.io/docs/configuration
+ */
+
+import type { Config } from "jest";
+import nextJest from "next/jest.js";
+
+const createJestConfig = nextJest({
+  // Provide the path to your Next.js app to load next.config.js and .env files in your test environment
+  dir: "./",
+});
+
+const config: Config = {
+  // All imported modules in your tests should be mocked automatically
+  // automock: false,
+
+  // Stop running tests after `n` failures
+  // bail: 0,
+
+  // The directory where Jest should store its cached dependency information
+  // cacheDirectory: "/private/var/folders/1b/bjy560yj24j3tdr6wx0dggkh0000gr/T/jest_e0",
+
+  // Automatically clear mock calls, instances, contexts and results before every test
+  clearMocks: true,
+
+  // Indicates whether the coverage information should be collected while executing the test
+  collectCoverage: true,
+
+  // An array of glob patterns indicating a set of files for which coverage information should be collected
+  // collectCoverageFrom: undefined,
+
+  // The directory where Jest should output its coverage files
+  coverageDirectory: "coverage",
+
+  // An array of regexp pattern strings used to skip coverage collection
+  // coveragePathIgnorePatterns: [
+  //   "/node_modules/"
+  // ],
+
+  // Indicates which provider should be used to instrument code for coverage
+  coverageProvider: "v8",
+
+  // A list of reporter names that Jest uses when writing coverage reports
+  // coverageReporters: [
+  //   "json",
+  //   "text",
+  //   "lcov",
+  //   "clover"
+  // ],
+
+  // An object that configures minimum threshold enforcement for coverage results
+  // coverageThreshold: undefined,
+
+  // A path to a custom dependency extractor
+  // dependencyExtractor: undefined,
+
+  // Make calling deprecated APIs throw helpful error messages
+  // errorOnDeprecated: false,
+
+  // The default configuration for fake timers
+  // fakeTimers: {
+  //   "enableGlobally": false
+  // },
+
+  // Force coverage collection from ignored files using an array of glob patterns
+  // forceCoverageMatch: [],
+
+  // A path to a module which exports an async function that is triggered once before all test suites
+  // globalSetup: undefined,
+
+  // A path to a module which exports an async function that is triggered once after all test suites
+  // globalTeardown: undefined,
+
+  // A set of global variables that need to be available in all test environments
+  // globals: {},
+
+  // The maximum amount of workers used to run your tests. Can be specified as % or a number. E.g. maxWorkers: 10% will use 10% of your CPU amount + 1 as the maximum worker number. maxWorkers: 2 will use a maximum of 2 workers.
+  // maxWorkers: "50%",
+
+  // An array of directory names to be searched recursively up from the requiring module's location
+  // moduleDirectories: [
+  //   "node_modules"
+  // ],
+
+  // An array of file extensions your modules use
+  // moduleFileExtensions: [
+  //   "js",
+  //   "mjs",
+  //   "cjs",
+  //   "jsx",
+  //   "ts",
+  //   "tsx",
+  //   "json",
+  //   "node"
+  // ],
+
+  // A map from regular expressions to module names or to arrays of module names that allow to stub out resources with a single module
+  // moduleNameMapper: {},
+
+  // An array of regexp pattern strings, matched against all module paths before considered 'visible' to the module loader
+  // modulePathIgnorePatterns: [],
+
+  // Activates notifications for test results
+  // notify: false,
+
+  // An enum that specifies notification mode. Requires { notify: true }
+  // notifyMode: "failure-change",
+
+  // A preset that is used as a base for Jest's configuration
+  // preset: undefined,
+
+  // Run tests from one or more projects
+  // projects: undefined,
+
+  // Use this configuration option to add custom reporters to Jest
+  // reporters: undefined,
+
+  // Automatically reset mock state before every test
+  // resetMocks: false,
+
+  // Reset the module registry before running each individual test
+  // resetModules: false,
+
+  // A path to a custom resolver
+  // resolver: undefined,
+
+  // Automatically restore mock state and implementation before every test
+  // restoreMocks: false,
+
+  // The root directory that Jest should scan for tests and modules within
+  // rootDir: undefined,
+
+  // A list of paths to directories that Jest should use to search for files in
+  // roots: [
+  //   "<rootDir>"
+  // ],
+
+  // Allows you to use a custom runner instead of Jest's default test runner
+  // runner: "jest-runner",
+
+  // The paths to modules that run some code to configure or set up the testing environment before each test
+  // setupFiles: [],
+
+  // A list of paths to modules that run some code to configure or set up the testing framework before each test
+  // setupFilesAfterEnv: [],
+
+  // The number of seconds after which a test is considered as slow and reported as such in the results.
+  // slowTestThreshold: 5,
+
+  // A list of paths to snapshot serializer modules Jest should use for snapshot testing
+  // snapshotSerializers: [],
+
+  // The test environment that will be used for testing
+  // testEnvironment: "jest-environment-node",
+
+  // Options that will be passed to the testEnvironment
+  // testEnvironmentOptions: {},
+
+  // Adds a location field to test results
+  // testLocationInResults: false,
+
+  // The glob patterns Jest uses to detect test files
+  // testMatch: [
+  //   "**/__tests__/**/*.[jt]s?(x)",
+  //   "**/?(*.)+(spec|test).[tj]s?(x)"
+  // ],
+
+  // An array of regexp pattern strings that are matched against all test paths, matched tests are skipped
+  // testPathIgnorePatterns: [
+  //   "/node_modules/"
+  // ],
+
+  // The regexp pattern or array of patterns that Jest uses to detect test files
+  // testRegex: [],
+
+  // This option allows the use of a custom results processor
+  // testResultsProcessor: undefined,
+
+  // This option allows use of a custom test runner
+  // testRunner: "jest-circus/runner",
+
+  // A map from regular expressions to paths to transformers
+  // transform: undefined,
+
+  // An array of regexp pattern strings that are matched against all source file paths, matched files will skip transformation
+  // transformIgnorePatterns: [
+  //   "/node_modules/",
+  //   "\\.pnp\\.[^\\/]+$"
+  // ],
+
+  // An array of regexp pattern strings that are matched against all modules before the module loader will automatically return a mock for them
+  // unmockedModulePathPatterns: undefined,
+
+  // Indicates whether each individual test should be reported during the run
+  // verbose: undefined,
+
+  // An array of regexp patterns that are matched against all source file paths before re-running tests in watch mode
+  // watchPathIgnorePatterns: [],
+
+  // Whether to use watchman for file crawling
+  // watchman: true,
+};
+
+// createJestConfig is exported this way to ensure that next/jest can load the Next.js config which is async
+export default createJestConfig(config);