Add FileSystem abstraction for testing

src/action-common.ts

@@ -1,9 +1,13 @@
+import * as fs from "fs";
+import * as os from "os";
+
 import * as core from "@actions/core";
 
 import { ActionsEnv, getActionsEnv } from "./actions-util";
 import type { ApiClient } from "./api-client";
 import { Env, ReadOnlyEnv } from "./environment";
 import type { FeatureEnablement } from "./feature-flags";
+import type { FileSystem } from "./fs";
 import { getActionsLogger, Logger } from "./logging";
 import {
   ActionName,
@@ -23,6 +27,8 @@ export interface BaseState {
   platform: NodeJS.Platform;
   /** The architecture of the host. */
   arch: NodeJS.Architecture;
+  /** The version of the operating system. */
+  osRelease: string;
 }
 
 /** Describes different state features that an Action may have. */
@@ -51,6 +57,10 @@ export interface FeatureState {
     /** Information about enabled feature flags. */
     features: FeatureEnablement;
   };
+  FS: {
+    /** The file system operations to use. */
+    fs: FileSystem;
+  };
 }
 
 /** Identifies a type of state an Action may have. */
@@ -74,7 +84,7 @@ export type ActionState<Fs extends readonly StateFeature[]> = FieldsOf<Fs>;
  * Each Action can then augment the `state` further if additional features are required.
  */
 export type ActionMain = (
-  state: ActionState<["Base", "Logger", "Env", "Actions"]>,
+  state: ActionState<["Base", "FS", "Logger", "Env", "Actions"]>,
 ) => Promise<void>;
 
 /** A specification for a CodeQL Action step. */
@@ -104,6 +114,8 @@ export async function runInActions(action: Action) {
       startedAt,
       platform: process.platform,
       arch: process.arch,
+      osRelease: os.release(),
+      fs,
       logger,
       env,
       actions: actionsEnv,

src/actions-util.ts

@@ -72,7 +72,7 @@ export const getOptionalInput = function (name: string): string | undefined {
  * directory that has been set in `CODEQL_ACTION_TEMP` by e.g. a previous step, or the
  * value of `RUNNER_TEMP` otherwise.
  */
-export function getTemporaryDirectory(env: Env = getEnv()): string {
+export function getTemporaryDirectory(env: ReadOnlyEnv = getEnv()): string {
   return (
     env.getOptional(EnvVar.TEMP) ?? env.getRequired(ActionsEnvVars.RUNNER_TEMP)
   );

src/cli/output-cache.ts

@@ -2,7 +2,7 @@ import * as fs from "fs";
 import path from "path";
 
 import { getTemporaryDirectory } from "../actions-util";
-import { Env } from "../environment";
+import { ReadOnlyEnv } from "../environment";
 import * as json from "../json";
 import { Logger } from "../logging";
 
@@ -51,7 +51,7 @@ export function resetCachedCodeQlVersion(): void {
  * Returns the path to the temporary file that backs the
  * on-disk cache of CLI responses between workflow steps.
  */
-export function getCommandCacheFilePath(env: Env): string {
+export function getCommandCacheFilePath(env: ReadOnlyEnv): string {
   return path.join(getTemporaryDirectory(env), COMMAND_CACHE_FILENAME);
 }
 

src/codeql.ts

@@ -17,7 +17,7 @@ import type { VersionInfo } from "./cli/types";
 import { CliError, wrapCliConfigurationError } from "./cli-errors";
 import { appendExtraQueryExclusions, type Config } from "./config-utils";
 import { DocUrl } from "./doc-url";
-import { EnvVar, getEnv, exportEnvVar } from "./environment";
+import { EnvVar, getEnv, exportEnvVar, Env, ReadOnlyEnv } from "./environment";
 import {
   CodeQLDefaultVersionInfo,
   Feature,
@@ -493,8 +493,9 @@ export function createStubCodeQL(partialCodeql: Partial<CodeQL>): CodeQL {
 export async function getCodeQLForTesting(
   cmd = "codeql-for-testing",
   logger: Logger = getRunnerLogger(true),
+  env: Env = getEnv(),
 ): Promise<CodeQL> {
-  return getCodeQLForCmd(logger, cmd, false);
+  return getCodeQLForCmd(logger, cmd, false, env);
 }
 
 /**
@@ -509,13 +510,14 @@ async function getCodeQLForCmd(
   logger: Logger,
   cmd: string,
   checkVersion: boolean,
+  env: Env = getEnv(),
 ): Promise<CodeQL> {
   const codeql: CodeQL = {
     getPath() {
       return cmd;
     },
     async getVersion() {
-      const cacheFilePath = outputCache.getCommandCacheFilePath(getEnv());
+      const cacheFilePath = outputCache.getCommandCacheFilePath(env);
       let result = outputCache.getCachedCodeQlVersion(
         logger,
         cacheFilePath,
@@ -641,7 +643,7 @@ async function getCodeQLForCmd(
       }
     },
     async runAutobuild(config: Config, language: Language) {
-      applyAutobuildAzurePipelinesTimeoutFix();
+      applyAutobuildAzurePipelinesTimeoutFix(env);
 
       const autobuildCmd = path.join(
         await this.resolveExtractor(language),
@@ -651,8 +653,11 @@ async function getCodeQLForCmd(
 
       // Bump the verbosity of the autobuild command if we're in debug mode
       if (config.debugMode) {
-        process.env[EnvVar.CLI_VERBOSITY] =
-          process.env[EnvVar.CLI_VERBOSITY] || EXTRACTION_DEBUG_MODE_VERBOSITY;
+        env.set(
+          EnvVar.CLI_VERBOSITY,
+          env.getOptional(EnvVar.CLI_VERBOSITY) ??
+            EXTRACTION_DEBUG_MODE_VERBOSITY,
+        );
       }
 
       // On macOS, System Integrity Protection (SIP) typically interferes with
@@ -684,7 +689,7 @@ async function getCodeQLForCmd(
     },
     async extractUsingBuildMode(config: Config, language: Language) {
       if (config.buildMode === BuildMode.Autobuild) {
-        applyAutobuildAzurePipelinesTimeoutFix();
+        applyAutobuildAzurePipelinesTimeoutFix(env);
       }
       try {
         await runCli(cmd, [
@@ -816,7 +821,7 @@ async function getCodeQLForCmd(
         "--sarif-group-rules-by-pack",
         "--sarif-include-query-help=always",
         "--sublanguage-file-coverage",
-        ...(await getJobRunUuidSarifOptions()),
+        ...(await getJobRunUuidSarifOptions(env)),
         ...getExtraOptionsFromEnv(["database", "interpret-results"]),
       ];
       if (sarifRunPropertyFlag !== undefined) {
@@ -1036,7 +1041,7 @@ async function getCodeQLForCmd(
     );
   } else if (
     checkVersion &&
-    process.env[EnvVar.SUPPRESS_DEPRECATED_SOON_WARNING] !== "true" &&
+    env.getOptional(EnvVar.SUPPRESS_DEPRECATED_SOON_WARNING) !== "true" &&
     !(await util.codeQlVersionAtLeast(codeql, CODEQL_NEXT_MINIMUM_VERSION))
   ) {
     const result = await codeql.getVersion();
@@ -1256,17 +1261,20 @@ function getExtractionVerbosityArguments(
  * Without the fix, long build processes will timeout when pulling down Java packages
  * https://developercommunity.visualstudio.com/content/problem/292284/maven-hosted-agent-connection-timeout.html
  */
-function applyAutobuildAzurePipelinesTimeoutFix() {
-  const javaToolOptions = process.env["JAVA_TOOL_OPTIONS"] || "";
-  process.env["JAVA_TOOL_OPTIONS"] = [
-    ...javaToolOptions.split(/\s+/),
-    "-Dhttp.keepAlive=false",
-    "-Dmaven.wagon.http.pool=false",
-  ].join(" ");
+function applyAutobuildAzurePipelinesTimeoutFix(env: Env) {
+  const javaToolOptions = env.getOptional("JAVA_TOOL_OPTIONS") ?? "";
+  env.set(
+    "JAVA_TOOL_OPTIONS",
+    [
+      ...javaToolOptions.split(/\s+/),
+      "-Dhttp.keepAlive=false",
+      "-Dmaven.wagon.http.pool=false",
+    ].join(" "),
+  );
 }
 
-async function getJobRunUuidSarifOptions() {
-  const jobRunUuid = process.env[EnvVar.JOB_RUN_UUID];
+async function getJobRunUuidSarifOptions(env: ReadOnlyEnv) {
+  const jobRunUuid = env.getOptional(EnvVar.JOB_RUN_UUID);
 
   return jobRunUuid ? [`--sarif-run-property=jobRunUuid=${jobRunUuid}`] : [];
 }

src/fs.ts

@@ -0,0 +1,35 @@
+/**
+ * This module exports a `FileSystem` type which corresponds to the interface of the "fs" module.
+ *
+ * Functions which are parameterised over this type can then be passed a different implementation in tests:
+ *
+ * ```typescript
+ * import * as nodefs from "fs";
+ *
+ * function foo(fs: FileSystem = nodefs) {
+ *   // Uses the real "fs" module by default, but can be given a different implementation.
+ * }
+ * ```
+ *
+ * The type can also be constrained to a subset of available operations. For example, in the following
+ * case we have a function that only needs `statSync`:
+ *
+ * ```
+ * function bar(fs: FileSystem<"statSync"> = nodefs) {
+ *   // This function can only use `statSync`.
+ * }
+ * ```
+ *
+ * This is useful to define a clearer interface for what the function does and also only requires stubbing
+ * of the relevant functions.
+ */
+
+import * as fs from "fs";
+
+/** Represents the names of operations exported from "fs". */
+export type FileOperation = keyof typeof fs;
+
+/** Represents the type of "fs", optionally filtered down to just `Ops`. */
+export type FileSystem<Ops extends FileOperation = keyof typeof fs> = {
+  [Key in Ops]: (typeof fs)[Key];
+};

src/init-action.ts

@@ -199,7 +199,7 @@ async function sendCompletedStatusReport(
 }
 
 async function run(
-  actionState: ActionState<["Base", "Logger", "Env", "Actions"]>,
+  actionState: ActionState<["Base", "Logger", "Env", "Actions", "FS"]>,
 ) {
   // To capture errors appropriately, keep as much code within the try-catch as
   // possible, and only use safe functions outside.

src/testing-utils.ts

@@ -1,4 +1,6 @@
+import * as fs from "fs";
 import { TextDecoder } from "node:util";
+import * as os from "os";
 import path from "path";
 
 import * as github from "@actions/github";
@@ -220,6 +222,7 @@ type AllState = [
   "Actions",
   "Api",
   "FeatureFlags",
+  "FS",
 ];
 
 /** Initialise a fresh `ActionState<AllState>` value. */
@@ -232,11 +235,13 @@ export function initAllState(
     startedAt: new Date(),
     platform: process.platform,
     arch: process.arch,
+    osRelease: os.release(),
     logger: new RecordingLogger(),
     env,
     actions: getTestActionsEnv(env),
     apiClient: github.getOctokit("123"),
     features: createFeatures([]),
+    fs,
     ...overrides,
   };
 }