test: share runtime scan filters and cached test scans

src/test-utils/repo-scan.ts

@@ -2,6 +2,18 @@ import fs from "node:fs/promises";
 import path from "node:path";
 
 export const DEFAULT_REPO_SCAN_SKIP_DIR_NAMES = new Set([".git", "dist", "node_modules"]);
+export const DEFAULT_RUNTIME_SOURCE_ROOTS = ["src", "extensions"] as const;
+export const DEFAULT_RUNTIME_SOURCE_EXTENSIONS = [".ts", ".tsx"] as const;
+export const RUNTIME_SOURCE_SKIP_PATTERNS = [
+  /\.test\.tsx?$/,
+  /\.test-helpers\.tsx?$/,
+  /\.test-utils\.tsx?$/,
+  /\.e2e\.tsx?$/,
+  /\.d\.ts$/,
+  /\/(?:__tests__|tests)\//,
+  /\/[^/]*test-helpers(?:\.[^/]+)?\.tsx?$/,
+  /\/[^/]*test-utils(?:\.[^/]+)?\.tsx?$/,
+] as const;
 
 export type RepoFileScanOptions = {
   roots: readonly string[];
@@ -10,10 +22,15 @@ export type RepoFileScanOptions = {
   skipHiddenDirectories?: boolean;
   shouldIncludeFile?: (relativePath: string) => boolean;
 };
+export type RuntimeSourceScanOptions = {
+  roots?: readonly string[];
+  extensions?: readonly string[];
+};
 
 type PendingDir = {
   absolutePath: string;
 };
+const runtimeSourceScanCache = new Map<string, Promise<Array<string>>>();
 
 function shouldSkipDirectory(
   name: string,
@@ -29,6 +46,18 @@ function hasAllowedExtension(fileName: string, extensions: readonly string[]): b
   return extensions.some((extension) => fileName.endsWith(extension));
 }
 
+function normalizeRelativePath(relativePath: string): string {
+  return relativePath.replaceAll("\\", "/");
+}
+
+function toSortedUnique(values: readonly string[]): Array<string> {
+  return [...new Set(values)].toSorted();
+}
+
+function getRuntimeScanCacheKey(repoRoot: string, roots: readonly string[]): string {
+  return `${repoRoot}::${toSortedUnique(roots).join(",")}`;
+}
+
 export async function listRepoFiles(
   repoRoot: string,
   options: RepoFileScanOptions,
@@ -76,3 +105,34 @@ export async function listRepoFiles(
   files.sort((a, b) => a.localeCompare(b));
   return files;
 }
+
+export function shouldSkipRuntimeSourcePath(relativePath: string): boolean {
+  const normalizedPath = normalizeRelativePath(relativePath);
+  return RUNTIME_SOURCE_SKIP_PATTERNS.some((pattern) => pattern.test(normalizedPath));
+}
+
+export async function listRuntimeSourceFiles(
+  repoRoot: string,
+  options: RuntimeSourceScanOptions = {},
+): Promise<Array<string>> {
+  const roots = options.roots ?? DEFAULT_RUNTIME_SOURCE_ROOTS;
+  const requestedExtensions = toSortedUnique(
+    options.extensions ?? DEFAULT_RUNTIME_SOURCE_EXTENSIONS,
+  );
+  const cacheKey = getRuntimeScanCacheKey(repoRoot, roots);
+
+  let pending = runtimeSourceScanCache.get(cacheKey);
+  if (!pending) {
+    pending = listRepoFiles(repoRoot, {
+      roots,
+      extensions: DEFAULT_RUNTIME_SOURCE_EXTENSIONS,
+      skipHiddenDirectories: true,
+      shouldIncludeFile: (relativePath) => !shouldSkipRuntimeSourcePath(relativePath),
+    });
+    runtimeSourceScanCache.set(cacheKey, pending);
+  }
+  const files = await pending;
+  return files.filter((filePath) =>
+    requestedExtensions.some((extension) => filePath.endsWith(extension)),
+  );
+}