Implement unit tests for cache stub

Author: ncalteen

__fixtures__/@actions/core.ts

@@ -3,6 +3,7 @@ import { jest } from '@jest/globals'
 export const debug = jest.fn().mockImplementation(() => {})
 export const error = jest.fn().mockImplementation(() => {})
 export const info = jest.fn().mockImplementation(() => {})
+export const isDebug = jest.fn().mockImplementation(() => false)
 export const getInput = jest.fn().mockImplementation(() => {})
 export const setOutput = jest.fn().mockImplementation(() => {})
 export const setFailed = jest.fn().mockImplementation(() => {})

__fixtures__/@actions/io.ts

@@ -0,0 +1,9 @@
+import { jest } from '@jest/globals'
+
+export const which = jest.fn().mockImplementation(() => {})
+export const mkdirP = jest.fn().mockImplementation(() => {})
+
+export default {
+  which,
+  mkdirP
+}

__fixtures__/fs.ts

@@ -1,21 +1,27 @@
 import { jest } from '@jest/globals'
 
 export const accessSync = jest.fn()
+export const copyFileSync = jest.fn()
 export const createWriteStream = jest.fn()
 export const createReadStream = jest.fn()
 export const existsSync = jest.fn()
 export const mkdirSync = jest.fn()
+export const readdirSync = jest.fn()
 export const readFileSync = jest.fn()
 export const rmSync = jest.fn()
 export const statSync = jest.fn()
+export const writeFileSync = jest.fn()
 
 export default {
   accessSync,
+  copyFileSync,
   createWriteStream,
   createReadStream,
   existsSync,
   mkdirSync,
+  readdirSync,
   readFileSync,
   rmSync,
-  statSync
+  statSync,
+  writeFileSync
 }