prependForwardSlash helper

src/createRedirect.ts

@@ -1,15 +1,15 @@
 import type { Redirects } from './index.js'
+import { prependForwardSlash } from './utils.js'
 
 export function createRedirect(
   redirects: Redirects,
   redirectFrom: string[],
   postSlug: string
 ) {
-  // Prepend all slugs with a slash if not present
+  postSlug = prependForwardSlash(postSlug)
-  if (!postSlug.startsWith('/')) postSlug = `/${postSlug}`
 
   for (let slug of redirectFrom) {
-    if (!slug.startsWith('/')) slug = `/${slug}`
+    slug = prependForwardSlash(slug)
     redirects[slug] = postSlug
   }
 

src/utils.ts

@@ -38,3 +38,7 @@ export async function writeJson<T>(path: PathLike, data: T) {
     encoding: 'utf-8'
   })
 }
+
+export function prependForwardSlash(str: string) {
+  return str.startsWith('/') ? str : '/' + str
+}

test/utils.test.ts

@@ -4,6 +4,7 @@ import {
   getMarkdownFiles,
   getMarkdownFrontmatter,
   getSlugFromFilePath,
+  prependForwardSlash,
   writeJson
 } from '../src/utils'
 
@@ -63,3 +64,29 @@ describe('writeJson', () => {
     expect(parsedContent).toEqual(testData)
   })
 })
+
+describe('prependForwardSlash', () => {
+  it('should prepend a forward slash if it does not start with one', () => {
+    const stringWithSlash = '/alreadyHasSlash'
+    const result1 = prependForwardSlash(stringWithSlash)
+    expect(result1).toBe('/alreadyHasSlash')
+  })
+
+  it('should prepend a forward slash', () => {
+    const stringWithoutSlash = 'noSlashAtStart'
+    const result2 = prependForwardSlash(stringWithoutSlash)
+    expect(result2).toBe('/noSlashAtStart')
+  })
+
+  it('should return a single forward slash if the input string is empty', () => {
+    const emptyString = ''
+    const result3 = prependForwardSlash(emptyString)
+    expect(result3).toBe('/')
+  })
+
+  it('should return a single forward slash if a slash is passed', () => {
+    const string = '/'
+    const result4 = prependForwardSlash(string)
+    expect(result4).toBe('/')
+  })
+})