feat: add tests for isFile

test/unit/node/util.test.ts

 import * as cp from "child_process"
+import * as path from "path"
+import { promises as fs } from "fs"
 import { generateUuid } from "../../../src/common/util"
 import * as util from "../../../src/node/util"
+import { tmpdir } from "../../../src/node/constants"
 
 describe("getEnvPaths", () => {
   describe("on darwin", () => {
@@ -464,9 +467,6 @@ describe("pathToFsPath", () => {
   it("should keep drive letter casing when set to true", () => {
     expect(util.pathToFsPath("/C:/far/bo", true)).toBe("C:/far/bo")
   })
-  it("should use the first string in a string array", () => {
-    expect(util.pathToFsPath("/hello/foo")).toBe("/hello/foo")
-  })
   it("should replace / with \\ on Windows", () => {
     let ORIGINAL_PLATFORM = process.platform
 
@@ -481,3 +481,23 @@ describe("pathToFsPath", () => {
     })
   })
 })
+
+describe("isFile", () => {
+  const testDir = path.join(tmpdir, "tests", "isFile")
+  let pathToFile = ""
+
+  beforeEach(async () => {
+    pathToFile = path.join(testDir, "foo.txt")
+    await fs.mkdir(testDir, { recursive: true })
+    await fs.writeFile(pathToFile, "hello")
+  })
+  afterEach(async () => {
+    await fs.rm(testDir, { recursive: true, force: true })
+  })
+  it("should return false if the path doesn't exist", async () => {
+    expect(await util.isFile(testDir)).toBe(false)
+  })
+  it("should return true if is file", async () => {
+    expect(await util.isFile(pathToFile)).toBe(true)
+  })
+})