Add read-only feature

When `read-only` is `true`, the cache is only restored and not saved. This allows for sharing the cache with multiple steps even if these steps may change them, and speeds them up regardless.

__tests__/restore.test.ts

@@ -308,3 +308,35 @@ test("restore with cache found for restore key", async () => {
     );
     expect(failedMock).toHaveBeenCalledTimes(0);
 });
+
+test("restore with read-only with cache found for key", async () => {
+    const path = "node_modules";
+    const key = "node-test";
+    testUtils.setInputs({
+        path: path,
+        key,
+        readOnly: true
+    });
+
+    const infoMock = jest.spyOn(core, "info");
+    const failedMock = jest.spyOn(core, "setFailed");
+    const stateMock = jest.spyOn(core, "saveState");
+    const setCacheHitOutputMock = jest.spyOn(actionUtils, "setCacheHitOutput");
+    const restoreCacheMock = jest
+        .spyOn(cache, "restoreCache")
+        .mockImplementationOnce(() => {
+            return Promise.resolve(key);
+        });
+
+    await run();
+
+    expect(restoreCacheMock).toHaveBeenCalledTimes(1);
+    expect(restoreCacheMock).toHaveBeenCalledWith([path], key, []);
+
+    expect(stateMock).toHaveBeenCalledWith("CACHE_KEY", key);
+    expect(setCacheHitOutputMock).toHaveBeenCalledTimes(1);
+    expect(setCacheHitOutputMock).toHaveBeenCalledWith(true);
+
+    expect(infoMock).toHaveBeenCalledWith(`Cache restored from key: ${key}`);
+    expect(failedMock).toHaveBeenCalledTimes(0);
+});

__tests__/save.test.ts

@@ -35,6 +35,14 @@ beforeAll(() => {
         }
     );
 
+    jest.spyOn(actionUtils, "getInputAsBoolean").mockImplementation(
+        (name, options) => {
+            return jest
+                .requireActual("../src/utils/actionUtils")
+                .getInputAsBoolean(name, options);
+        }
+    );
+
     jest.spyOn(actionUtils, "isExactKeyMatch").mockImplementation(
         (key, cacheResult) => {
             return jest
@@ -338,3 +346,32 @@ test("save with valid inputs uploads a cache", async () => {
 
     expect(failedMock).toHaveBeenCalledTimes(0);
 });
+
+test("save with read-only does not upload cache", async () => {
+    const infoMock = jest.spyOn(core, "info");
+    const failedMock = jest.spyOn(core, "setFailed");
+
+    const primaryKey = "Linux-node-bb828da54c148048dd17899ba9fda624811cfb43";
+    const savedCacheKey = primaryKey;
+
+    jest.spyOn(core, "getState")
+        // Cache Entry State
+        .mockImplementationOnce(() => {
+            return savedCacheKey;
+        })
+        // Cache Key State
+        .mockImplementationOnce(() => {
+            return primaryKey;
+        });
+    const saveCacheMock = jest.spyOn(cache, "saveCache");
+
+    testUtils.setInput(Inputs.ReadOnly, "true");
+
+    await run();
+
+    expect(saveCacheMock).toHaveBeenCalledTimes(0);
+    expect(infoMock).toHaveBeenCalledWith(
+        "Cache running in read-only mode, not saving cache."
+    );
+    expect(failedMock).toHaveBeenCalledTimes(0);
+});

action.yml

@@ -14,6 +14,9 @@ inputs:
   upload-chunk-size:
     description: 'The chunk size used to split up large files during upload, in bytes'
     required: false
+  read-only:
+    description: 'Set to true to never save the cache'
+    required: false
 outputs:
   cache-hit:
     description: 'A boolean value to indicate an exact match was found for the primary key'

src/constants.ts

@@ -2,7 +2,8 @@ export enum Inputs {
     Key = "key",
     Path = "path",
     RestoreKeys = "restore-keys",
-    UploadChunkSize = "upload-chunk-size"
+    UploadChunkSize = "upload-chunk-size",
+    ReadOnly = "read-only"
 }
 
 export enum Outputs {

src/save.ts

@@ -11,6 +11,11 @@ async function run(): Promise<void> {
             return;
         }
 
+        if (utils.getInputAsBoolean(Inputs.ReadOnly)) {
+            core.info("Cache running in read-only mode, not saving cache.");
+            return;
+        }
+
         if (!utils.isValidEvent()) {
             utils.logWarning(
                 `Event Validation Error: The event type ${

src/utils/actionUtils.ts

@@ -74,3 +74,10 @@ export function getInputAsInt(
     }
     return value;
 }
+
+export function getInputAsBoolean(
+    name: string,
+    options?: core.InputOptions
+): boolean {
+    return core.getInput(name, options) === "true";
+}

src/utils/testUtils.ts

@@ -13,6 +13,7 @@ interface CacheInput {
     path: string;
     key: string;
     restoreKeys?: string[];
+    readOnly?: boolean;
 }
 
 export function setInputs(input: CacheInput): void {
@@ -20,6 +21,7 @@ export function setInputs(input: CacheInput): void {
     setInput(Inputs.Key, input.key);
     input.restoreKeys &&
         setInput(Inputs.RestoreKeys, input.restoreKeys.join("\n"));
+    setInput(Inputs.ReadOnly, input.readOnly ? "true" : "false");
 }
 
 export function clearInputs(): void {
@@ -27,4 +29,5 @@ export function clearInputs(): void {
     delete process.env[getInputName(Inputs.Key)];
     delete process.env[getInputName(Inputs.RestoreKeys)];
     delete process.env[getInputName(Inputs.UploadChunkSize)];
+    delete process.env[getInputName(Inputs.ReadOnly)];
 }