Cache validated checksums for later executions

The most common case for validation will be that the wrapper jars are unchanged
from a previous workflow run. In this case, we cache the validated wrapper
checksums to minimise the work required on a subsequent run.

Fixes #172

sources/test/jest/wrapper-validation/validate.test.ts

@@ -1,11 +1,15 @@
 import * as path from 'path'
+import * as fs from 'fs'
 import * as validate from '../../../src/wrapper-validation/validate'
 import {expect, test, jest} from '@jest/globals'
 import { WrapperChecksums } from '../../../src/wrapper-validation/checksums'
+import { ChecksumCache } from '../../../src/wrapper-validation/cache'
+import exp from 'constants'
 
 jest.setTimeout(30000)
 
 const baseDir = path.resolve('./test/jest/wrapper-validation')
+const tmpDir = path.resolve('./test/jest/tmp')
 
 test('succeeds if all found wrapper jars are valid', async () => {
   const result = await validate.findInvalidWrapperJars(baseDir, 3, false, [
@@ -24,6 +28,24 @@ test('succeeds if all found wrapper jars are valid', async () => {
   )
 })
 
+test('succeeds if all found wrapper jars are previously valid', async () => {
+  const result = await validate.findInvalidWrapperJars(baseDir, 3, false, [], [
+    'e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855',
+    '3888c76faa032ea8394b8a54e04ce2227ab1f4be64f65d450f8509fe112d38ce'
+  ])
+
+  expect(result.isValid()).toBe(true)
+  // Only hardcoded and explicitly allowed checksums should have been used
+  expect(result.fetchedChecksums).toBe(false)
+
+  expect(result.toDisplayString()).toBe(
+    '✓ Found known Gradle Wrapper JAR files:\n' +
+      '  e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 data/invalid/gradle-wrapper.jar\n' +
+      '  e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855 data/invalid/gradlе-wrapper.jar\n' + // homoglyph
+      '  3888c76faa032ea8394b8a54e04ce2227ab1f4be64f65d450f8509fe112d38ce data/valid/gradle-wrapper.jar'
+  )
+})
+
 test('succeeds if all found wrapper jars are valid (and checksums are fetched from Gradle API)', async () => {
   const knownValidChecksums = new WrapperChecksums()
   const result = await validate.findInvalidWrapperJars(
@@ -31,6 +53,7 @@ test('succeeds if all found wrapper jars are valid (and checksums are fetched fr
     1,
     false,
     ['e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855'],
+    [],
     knownValidChecksums
   )
   console.log(`fetchedChecksums = ${result.fetchedChecksums}`)
@@ -98,3 +121,17 @@ test('fails if not enough wrapper jars are found', async () => {
       '  3888c76faa032ea8394b8a54e04ce2227ab1f4be64f65d450f8509fe112d38ce data/valid/gradle-wrapper.jar'
   )
 })
+
+test('can save and load checksums', async () => {
+  const cacheDir = path.join(tmpDir, 'wrapper-validation-cache')
+  fs.rmSync(cacheDir, {recursive: true, force: true})
+
+  const checksumCache = new ChecksumCache(cacheDir)
+
+  expect(checksumCache.load()).toEqual([])
+
+  checksumCache.save(['123', '456'])
+
+  expect(checksumCache.load()).toEqual(['123', '456'])
+  expect(fs.existsSync(cacheDir)).toBe(true)
+})