tests: add copyFile function in test-utils

test/test-utils.test.js

@@ -1,7 +1,7 @@
 "use strict";
 
-const { extractHash, appendDataIfFileExists } = require("./testUtils");
-const { writeFileSync, unlinkSync, readFileSync } = require("fs");
+const { extractHash, appendDataIfFileExists, copyFile } = require("./testUtils");
+const { writeFileSync, unlinkSync, readFileSync, existsSync } = require("fs");
 const { resolve } = require("path");
 
 describe("extractHash functionality", () => {
@@ -106,19 +106,20 @@ Child ${config2Name}:
 
 describe("appendFile functionality", () => {
 	describe("positive test-cases", () => {
-		const junkFile = resolve(__dirname, "junkFile.js");
+		const junkFile = "junkFile.js";
+		const junkFilePath = resolve(__dirname, junkFile);
 		const initialJunkData = "initial junk data";
 		const junkComment = "//junk comment";
 
 		beforeEach(() => {
-			writeFileSync(junkFile, initialJunkData);
+			writeFileSync(junkFilePath, initialJunkData);
 		});
 		afterEach(() => {
-			unlinkSync(junkFile);
+			unlinkSync(junkFilePath);
 		});
 		it("should append data to file if file exists", () => {
 			appendDataIfFileExists(__dirname, junkFile, junkComment);
-			const actualData = readFileSync(junkFile).toString();
+			const actualData = readFileSync(junkFilePath).toString();
 
 			expect(actualData).toBe(initialJunkData + junkComment);
 		});
@@ -130,3 +131,34 @@ describe("appendFile functionality", () => {
 		});
 	});
 });
+
+describe("copyFile functionality", () => {
+	describe("positive test-cases", () => {
+		const originalFile = "junkFile.js";
+		const originalFilePath = resolve(__dirname, originalFile);
+		const originalFileData = "initial junk data";
+		var copyFilePath;
+
+		beforeEach(() => {
+			writeFileSync(originalFilePath, originalFileData);
+		});
+		afterEach(() => {
+			unlinkSync(originalFilePath);
+			if (existsSync(copyFilePath)) {
+				unlinkSync(copyFilePath);
+			}
+		});
+		it("should copy file if file exists", () => {
+			copyFilePath = copyFile(__dirname, originalFile);
+			const actualData = readFileSync(copyFilePath).toString();
+
+			expect(actualData).toBe(originalFileData);
+		});
+	});
+
+	describe("negative test-cases", () => {
+		it("should throw error if file does not exist", () => {
+			expect(() => copyFile(__dirname, "does-not-exist.js")).toThrowError();
+		});
+	});
+});

test/testUtils.js

@@ -1,6 +1,7 @@
 "use strict";
 
 const path = require("path");
+const fs = require("fs");
 const execa = require("execa");
 const { sync: spawnSync } = execa;
 const { Writable } = require("readable-stream");
@@ -171,14 +172,33 @@ function extractHash(stdout) {
  * @throws - throw an Error if file does not exist
  */
 function appendDataIfFileExists(testCase, file, data) {
-	const { existsSync, appendFileSync } = require("fs");
-
 	const filePath = path.resolve(testCase, file);
-	if (existsSync(filePath)) {
-		appendFileSync(filePath, data);
+	if (fs.existsSync(filePath)) {
+		fs.appendFileSync(filePath, data);
 	} else {
 		throw new Error(`Oops! ${filePath} does not exist!`);
 	}
 }
 
-module.exports = { run, runWatch, runAndGetWatchProc, extractHash, extractSummary, appendDataIfFileExists };
+/**
+ * fs.copyFileSync was added in Added in: v8.5.0
+ * We should refactor the below code once our minimal supported version is v8.5.0
+ * @param {String} testCase - testCase directory
+ * @param {String} file - file relative to testCase which is going to be copied
+ * @returns {String} - absolute file path of new file
+ * @throws - throw an Error if file copy fails
+ */
+function copyFile(testCase, file) {
+	const fileToChangePath = path.resolve(testCase, file);
+	const copyFilePath = path.resolve(testCase, "index_copy.js");
+
+	if (fs.existsSync(fileToChangePath)) {
+		const fileData = fs.readFileSync(fileToChangePath).toString();
+		fs.writeFileSync(copyFilePath, fileData);
+		return copyFilePath;
+	} else {
+		throw new Error(`Oops! ${fileToChangePath} does not exist!`);
+	}
+}
+
+module.exports = { run, runWatch, runAndGetWatchProc, extractHash, extractSummary, appendDataIfFileExists, copyFile };