13 add tests

jest.config.js

@@ -0,0 +1,19 @@
+/** @type {import('ts-jest').JestConfigWithTsJest} */
+module.exports = {
+	preset: 'ts-jest',
+	testEnvironment: 'node',
+	collectCoverage: true,
+	collectCoverageFrom: ['src/**/*.ts'],
+	coverageDirectory: 'coverage',
+	coverageProvider: 'v8',
+	transform: {
+		'^.+\\.ts$': [
+			'ts-jest',
+			{
+				diagnostics: {
+					warnOnly: true,
+				},
+			},
+		],
+	},
+};

package.json

@@ -40,7 +40,8 @@
 		"build": "tsc",
 		"watch": "tsc --watch",
 		"clean": "tsc --build --clean",
-		"prepare": "npm run build"
+		"test": "jest",
+		"prepare": "npm run test && npm run build"
 	},
 	"peerDependencies": {
 		"gatsby": "^5.0.0-next"
@@ -51,10 +52,14 @@
 	},
 	"devDependencies": {
 		"@biomejs/biome": "1.7.3",
+		"@jest/globals": "^29.7.0",
 		"@tsconfig/node20": "^20.1.4",
 		"@types/express": "^4.17.21",
 		"gatsby": "^5.0.0-next",
 		"gatsby-plugin-utils": "^4.0.0",
+		"jest": "^29.7.0",
+		"joi": "^17.13.1",
+		"ts-jest": "^29.1.4",
 		"typescript": "^5.4.5"
 	},
 	"engines": {

src/gatsby-node.ts

@@ -3,7 +3,7 @@ import { setDefaultOptions, setGatsbyCreatePageFunction } from './config';
 import { generateImages } from './generator';
 import { info, setReporter } from './logger';
 import type { DefaultOptions } from './types';
-import { prettify } from './utilities';
+import { prettify } from './utils';
 import { getPluginOptionsSchema, setJoi } from './validator';
 
 // Save the reporter and createPage function for later use

src/index.ts

@@ -6,7 +6,7 @@ import {
 } from './config';
 import { info } from './logger';
 import type { DefaultOptions, JobOptions } from './types';
-import { prettify } from './utilities';
+import { prettify } from './utils';
 import { validateJobOptions } from './validator';
 
 // Public function for setting default options

src/logger.test.ts

@@ -0,0 +1,149 @@
+import {
+	beforeAll,
+	beforeEach,
+	describe,
+	expect,
+	it,
+	jest,
+} from '@jest/globals';
+import type { Reporter } from 'gatsby';
+import Joi from 'joi';
+import { setDefaultOptions } from './config';
+import {
+	endActivity,
+	error,
+	info,
+	panic,
+	setReporter,
+	startActivity,
+	success,
+	updateActivity,
+	warn,
+} from './logger';
+import { setJoi } from './validator';
+
+describe('info', () => {
+	let reporter: Reporter;
+
+	beforeEach(() => {
+		// @ts-expect-error: Reporter is intentially not fully mocked
+		reporter = {
+			info: jest.fn(),
+		};
+		// @ts-expect-error: Gatsby's PluginOptionsSchemaJoi type has an additional `subPlugins` property that we don't need
+		setJoi(Joi);
+		setDefaultOptions({ verbose: false });
+		setReporter(reporter);
+	});
+
+	it('should log an info message when verbose is true', () => {
+		setDefaultOptions({ verbose: true });
+		info('This is an info message');
+		expect(reporter.info).toHaveBeenCalledWith(
+			'gatsby-plugin-component-to-image: This is an info message',
+		);
+	});
+
+	it('should not log an info message when verbose is false', () => {
+		setDefaultOptions({ verbose: false });
+		info('This is an info message');
+		expect(reporter.info).not.toHaveBeenCalled();
+	});
+});
+
+describe('success', () => {
+	it('should log a success message', () => {
+		const reporter = {
+			success: jest.fn(),
+		};
+
+		// @ts-expect-error: Reporter is intentially not fully mocked
+		setReporter(reporter);
+		success('This is a success message');
+		expect(reporter.success).toHaveBeenCalledWith(
+			'gatsby-plugin-component-to-image: This is a success message',
+		);
+	});
+});
+
+describe('warn', () => {
+	it('should log a warning message', () => {
+		const reporter = {
+			warn: jest.fn(),
+		};
+
+		// @ts-expect-error: Reporter is intentially not fully mocked
+		setReporter(reporter);
+		warn('This is a warning message');
+		expect(reporter.warn).toHaveBeenCalledWith(
+			'gatsby-plugin-component-to-image: This is a warning message',
+		);
+	});
+});
+
+describe('error', () => {
+	it('should log an error message', () => {
+		const reporter = {
+			error: jest.fn(),
+		};
+
+		// @ts-expect-error: Reporter is intentially not fully mocked
+		setReporter(reporter);
+		error('This is an error message');
+		expect(reporter.error).toHaveBeenCalledWith(
+			'gatsby-plugin-component-to-image: This is an error message',
+		);
+	});
+});
+
+describe('panic', () => {
+	it('should log a panic message', () => {
+		const reporter = {
+			panic: jest.fn(),
+		};
+
+		// @ts-expect-error: Reporter is intentially not fully mocked
+		setReporter(reporter);
+		panic('This is a panic message');
+		expect(reporter.panic).toHaveBeenCalledWith(
+			'gatsby-plugin-component-to-image: This is a panic message',
+		);
+	});
+});
+
+describe('startActivity, updateActivity, and endActivity', () => {
+	const reporter = {
+		activityTimer: jest.fn(),
+	};
+	const activity = {
+		start: jest.fn(),
+		setStatus: jest.fn(),
+		end: jest.fn(),
+	};
+
+	beforeAll(() => {
+		reporter.activityTimer.mockReturnValue(activity);
+
+		// @ts-expect-error: Reporter is intentially not fully mocked
+		setReporter(reporter);
+	});
+
+	it('startActivity should start an activity', () => {
+		startActivity('Timer');
+		expect(reporter.activityTimer).toHaveBeenCalledWith(
+			'gatsby-plugin-component-to-image: Timer',
+		);
+		expect(activity.start).toHaveBeenCalled();
+	});
+
+	it('updateActivity should update the status of an activity', () => {
+		updateActivity('Status');
+		expect(activity.setStatus).toHaveBeenCalledWith('Status');
+	});
+
+	it('endActivity should end an activity', () => {
+		endActivity();
+		expect(activity.setStatus).toHaveBeenCalledWith('');
+		expect(activity.end).toHaveBeenCalled();
+	});
+});

src/logger.ts

@@ -1,6 +1,6 @@
 import type { Reporter } from 'gatsby';
 import { getDefaultOptions } from './config';
-import { getPackageName } from './utilities';
+import { getPackageName } from './utils';
 
 const LOG_PREFIX = `${getPackageName()}: ` as const;
 

src/utils.test.ts

@@ -0,0 +1,36 @@
+import { describe, expect, it } from '@jest/globals';
+import { assertIsDefined, getPackageName, prettify } from './utils';
+
+describe('assertIsDefined', () => {
+	it('should throw an error if value is undefined', () => {
+		expect(() => assertIsDefined(undefined)).toThrow(
+			'Expected value to be defined, but it was not',
+		);
+	});
+
+	it('should not throw an error if value is defined', () => {
+		expect(() => assertIsDefined('defined value')).not.toThrow();
+	});
+});
+
+describe('getPackageName', () => {
+	it('should return the package name from package.json', () => {
+		expect(getPackageName()).toBe('gatsby-plugin-component-to-image');
+	});
+});
+
+describe('prettify', () => {
+	it('should format an object as a human-readable string', () => {
+		const obj = {
+			name: 'Timmy',
+			size: 'chonky',
+			color: 'orange',
+		};
+		const expectedOutput = `{
+  "name": "Timmy",
+  "size": "chonky",
+  "color": "orange"
+}`;
+		expect(prettify(obj)).toBe(expectedOutput);
+	});
+});