refactor(themes): build paths in rewriteJsAndCss with path.join

Matches the read side in migrate.ts and addresses a review nit. Tests
follow the same pattern so they stay portable on Windows.

Author: luis-almeida

packages/zcli-themes/src/lib/rewriteJsAndCss.test.ts

@@ -1,5 +1,6 @@
 import * as sinon from 'sinon'
 import * as fs from 'fs'
+import * as path from 'path'
 import { expect } from '@oclif/test'
 import rewriteJsAndCss from './rewriteJsAndCss'
 
@@ -17,27 +18,29 @@ describe('rewriteJsAndCss', () => {
     })
 
     expect(writeFileSyncStub.callCount).to.equal(2)
-    expect(writeFileSyncStub.firstCall.args[0]).to.equal('theme/path/style.css')
+    expect(writeFileSyncStub.firstCall.args[0]).to.equal(path.join('theme/path', 'style.css'))
     expect(writeFileSyncStub.firstCall.args[1]).to.equal('body { color: red; }')
-    expect(writeFileSyncStub.secondCall.args[0]).to.equal('theme/path/script.js')
+    expect(writeFileSyncStub.secondCall.args[0]).to.equal(path.join('theme/path', 'script.js'))
     expect(writeFileSyncStub.secondCall.args[1]).to.equal('console.log("hi")')
   })
 
   it('throws if style.css cannot be written', () => {
+    const cssPath = path.join('theme/path', 'style.css')
     const writeFileSyncStub = sinon.stub(fs, 'writeFileSync')
-    writeFileSyncStub.withArgs('theme/path/style.css').throws(new Error('Permission denied'))
+    writeFileSyncStub.withArgs(cssPath).throws(new Error('Permission denied'))
 
     expect(() => {
       rewriteJsAndCss('theme/path', { css: 'a', js: 'b' })
-    }).to.throw('Failed to write file: theme/path/style.css')
+    }).to.throw(`Failed to write file: ${cssPath}`)
   })
 
   it('throws if script.js cannot be written', () => {
+    const jsPath = path.join('theme/path', 'script.js')
     const writeFileSyncStub = sinon.stub(fs, 'writeFileSync')
-    writeFileSyncStub.withArgs('theme/path/script.js').throws(new Error('Permission denied'))
+    writeFileSyncStub.withArgs(jsPath).throws(new Error('Permission denied'))
 
     expect(() => {
       rewriteJsAndCss('theme/path', { css: 'a', js: 'b' })
-    }).to.throw('Failed to write file: theme/path/script.js')
+    }).to.throw(`Failed to write file: ${jsPath}`)
   })
 })

packages/zcli-themes/src/lib/rewriteJsAndCss.ts

@@ -1,13 +1,14 @@
 import { CLIError } from '@oclif/core/lib/errors'
 import * as fs from 'fs'
+import * as path from 'path'
 import * as chalk from 'chalk'
 
 export default function rewriteJsAndCss (
   themePath: string,
   { css, js }: { css: string; js: string }
 ) {
-  const cssPath = `${themePath}/style.css`
-  const jsPath = `${themePath}/script.js`
+  const cssPath = path.join(themePath, 'style.css')
+  const jsPath = path.join(themePath, 'script.js')
 
   try {
     fs.writeFileSync(cssPath, css)