feat(core): add IgnoreFilter module with .understandignore parsing and tests

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

understand-anything-plugin/packages/core/src/__tests__/ignore-filter.test.ts

@@ -0,0 +1,153 @@
+import { describe, it, expect, beforeEach, afterEach } from "vitest";
+import { createIgnoreFilter, DEFAULT_IGNORE_PATTERNS } from "../ignore-filter";
+import { mkdirSync, writeFileSync, rmSync } from "node:fs";
+import { join } from "node:path";
+import { tmpdir } from "node:os";
+
+describe("IgnoreFilter", () => {
+  let testDir: string;
+
+  beforeEach(() => {
+    testDir = join(tmpdir(), `ignore-filter-test-${Date.now()}`);
+    mkdirSync(testDir, { recursive: true });
+    mkdirSync(join(testDir, ".understand-anything"), { recursive: true });
+  });
+
+  afterEach(() => {
+    rmSync(testDir, { recursive: true, force: true });
+  });
+
+  describe("DEFAULT_IGNORE_PATTERNS", () => {
+    it("contains node_modules", () => {
+      expect(DEFAULT_IGNORE_PATTERNS).toContain("node_modules/");
+    });
+
+    it("contains .git", () => {
+      expect(DEFAULT_IGNORE_PATTERNS).toContain(".git/");
+    });
+
+    it("contains bin and obj for .NET", () => {
+      expect(DEFAULT_IGNORE_PATTERNS).toContain("bin/");
+      expect(DEFAULT_IGNORE_PATTERNS).toContain("obj/");
+    });
+
+    it("contains build output directories", () => {
+      expect(DEFAULT_IGNORE_PATTERNS).toContain("dist/");
+      expect(DEFAULT_IGNORE_PATTERNS).toContain("build/");
+      expect(DEFAULT_IGNORE_PATTERNS).toContain("out/");
+      expect(DEFAULT_IGNORE_PATTERNS).toContain("coverage/");
+    });
+  });
+
+  describe("createIgnoreFilter with no user file", () => {
+    it("ignores files matching default patterns", () => {
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("node_modules/foo/bar.js")).toBe(true);
+      expect(filter.isIgnored("dist/index.js")).toBe(true);
+      expect(filter.isIgnored(".git/config")).toBe(true);
+      expect(filter.isIgnored("bin/Debug/app.dll")).toBe(true);
+      expect(filter.isIgnored("obj/Release/net8.0/app.dll")).toBe(true);
+    });
+
+    it("does not ignore source files", () => {
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("src/index.ts")).toBe(false);
+      expect(filter.isIgnored("README.md")).toBe(false);
+      expect(filter.isIgnored("package.json")).toBe(false);
+    });
+
+    it("ignores lock files", () => {
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("pnpm-lock.yaml")).toBe(true);
+      expect(filter.isIgnored("package-lock.json")).toBe(true);
+      expect(filter.isIgnored("yarn.lock")).toBe(true);
+    });
+
+    it("ignores binary/asset files", () => {
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("logo.png")).toBe(true);
+      expect(filter.isIgnored("font.woff2")).toBe(true);
+      expect(filter.isIgnored("doc.pdf")).toBe(true);
+    });
+
+    it("ignores generated files", () => {
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("bundle.min.js")).toBe(true);
+      expect(filter.isIgnored("style.min.css")).toBe(true);
+      expect(filter.isIgnored("source.map")).toBe(true);
+    });
+
+    it("ignores IDE directories", () => {
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored(".idea/workspace.xml")).toBe(true);
+      expect(filter.isIgnored(".vscode/settings.json")).toBe(true);
+    });
+  });
+
+  describe("createIgnoreFilter with user .understandignore", () => {
+    it("reads patterns from .understand-anything/.understandignore", () => {
+      writeFileSync(
+        join(testDir, ".understand-anything", ".understandignore"),
+        "# Exclude tests\n__tests__/\n*.test.ts\n"
+      );
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("__tests__/foo.test.ts")).toBe(true);
+      expect(filter.isIgnored("src/utils.test.ts")).toBe(true);
+      expect(filter.isIgnored("src/utils.ts")).toBe(false);
+    });
+
+    it("reads patterns from project root .understandignore", () => {
+      writeFileSync(
+        join(testDir, ".understandignore"),
+        "docs/\n"
+      );
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("docs/README.md")).toBe(true);
+      expect(filter.isIgnored("src/index.ts")).toBe(false);
+    });
+
+    it("handles # comments and blank lines", () => {
+      writeFileSync(
+        join(testDir, ".understand-anything", ".understandignore"),
+        "# This is a comment\n\n\nfixtures/\n\n# Another comment\n"
+      );
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("fixtures/data.json")).toBe(true);
+      expect(filter.isIgnored("src/index.ts")).toBe(false);
+    });
+
+    it("supports ! negation to override defaults", () => {
+      writeFileSync(
+        join(testDir, ".understand-anything", ".understandignore"),
+        "!dist/\n"
+      );
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("dist/index.js")).toBe(false);
+    });
+
+    it("supports ** recursive matching", () => {
+      writeFileSync(
+        join(testDir, ".understand-anything", ".understandignore"),
+        "**/snapshots/\n"
+      );
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("src/components/snapshots/Button.snap")).toBe(true);
+      expect(filter.isIgnored("snapshots/foo.snap")).toBe(true);
+    });
+
+    it("merges .understand-anything/ and root .understandignore", () => {
+      writeFileSync(
+        join(testDir, ".understand-anything", ".understandignore"),
+        "__tests__/\n"
+      );
+      writeFileSync(
+        join(testDir, ".understandignore"),
+        "fixtures/\n"
+      );
+      const filter = createIgnoreFilter(testDir);
+      expect(filter.isIgnored("__tests__/foo.ts")).toBe(true);
+      expect(filter.isIgnored("fixtures/data.json")).toBe(true);
+      expect(filter.isIgnored("src/index.ts")).toBe(false);
+    });
+  });
+});

understand-anything-plugin/packages/core/src/ignore-filter.ts

@@ -0,0 +1,112 @@
+import ignore, { type Ignore } from "ignore";
+import { readFileSync, existsSync } from "node:fs";
+import { join } from "node:path";
+
+/**
+ * Hardcoded default ignore patterns matching the project-scanner agent's
+ * exclusion rules, plus bin/obj for .NET projects.
+ */
+export const DEFAULT_IGNORE_PATTERNS: string[] = [
+  // Dependency directories
+  "node_modules/",
+  ".git/",
+  "vendor/",
+  "venv/",
+  ".venv/",
+  "__pycache__/",
+
+  // Build output
+  "dist/",
+  "build/",
+  "out/",
+  "coverage/",
+  ".next/",
+  ".cache/",
+  ".turbo/",
+  "target/",
+  "bin/",
+  "obj/",
+
+  // Lock files
+  "*.lock",
+  "package-lock.json",
+  "yarn.lock",
+  "pnpm-lock.yaml",
+
+  // Binary/asset files
+  "*.png",
+  "*.jpg",
+  "*.jpeg",
+  "*.gif",
+  "*.svg",
+  "*.ico",
+  "*.woff",
+  "*.woff2",
+  "*.ttf",
+  "*.eot",
+  "*.mp3",
+  "*.mp4",
+  "*.pdf",
+  "*.zip",
+  "*.tar",
+  "*.gz",
+
+  // Generated files
+  "*.min.js",
+  "*.min.css",
+  "*.map",
+  "*.generated.*",
+
+  // IDE/editor
+  ".idea/",
+  ".vscode/",
+
+  // Misc
+  "LICENSE",
+  ".gitignore",
+  ".editorconfig",
+  ".prettierrc",
+  ".eslintrc*",
+  "*.log",
+];
+
+export interface IgnoreFilter {
+  /** Returns true if the given relative path should be excluded from analysis. */
+  isIgnored(relativePath: string): boolean;
+}
+
+/**
+ * Creates an IgnoreFilter that merges hardcoded defaults with user-defined
+ * patterns from .understandignore files.
+ *
+ * Pattern load order (later entries can override earlier ones via ! negation):
+ * 1. Hardcoded defaults
+ * 2. .understand-anything/.understandignore (if exists)
+ * 3. .understandignore at project root (if exists)
+ */
+export function createIgnoreFilter(projectRoot: string): IgnoreFilter {
+  const ig: Ignore = ignore();
+
+  // Layer 1: hardcoded defaults
+  ig.add(DEFAULT_IGNORE_PATTERNS);
+
+  // Layer 2: .understand-anything/.understandignore
+  const projectIgnorePath = join(projectRoot, ".understand-anything", ".understandignore");
+  if (existsSync(projectIgnorePath)) {
+    const content = readFileSync(projectIgnorePath, "utf-8");
+    ig.add(content);
+  }
+
+  // Layer 3: .understandignore at project root
+  const rootIgnorePath = join(projectRoot, ".understandignore");
+  if (existsSync(rootIgnorePath)) {
+    const content = readFileSync(rootIgnorePath, "utf-8");
+    ig.add(content);
+  }
+
+  return {
+    isIgnored(relativePath: string): boolean {
+      return ig.ignores(relativePath);
+    },
+  };
+}