fix: ignore .d.ts files

Closes #195

packages/cli/src/Config.ts

@@ -14,6 +14,7 @@ import AstExplorerResolver from './resolvers/AstExplorerResolver';
 import FileSystemResolver from './resolvers/FileSystemResolver';
 import NetworkResolver from './resolvers/NetworkResolver';
 import PackageResolver from './resolvers/PackageResolver';
+import { EntryType } from './System';
 import { disable, enable } from './transpile-requires';
 
 export class Plugin {
@@ -33,8 +34,18 @@ export class Plugin {
   }
 }
 
-function ignoreDotfiles(path: string, basename: string, root: string): boolean {
-  return basename.startsWith('.');
+function defaultIgnorePredicate(
+  path: string,
+  basename: string,
+  root: string,
+  type: EntryType
+): boolean {
+  return (
+    // ignore paths starting with a dot
+    basename.startsWith('.') ||
+    // ignore TypeScript declaration files
+    basename.endsWith('.d.ts')
+  );
 }
 
 export enum Printer {
@@ -55,7 +66,7 @@ export default class Config {
     readonly requires: Array<string> = [],
     readonly transpilePlugins: boolean = true,
     readonly findBabelConfig: boolean = false,
-    readonly ignore: PathPredicate = ignoreDotfiles,
+    readonly ignore: PathPredicate = defaultIgnorePredicate,
     readonly stdio: boolean = false,
     readonly dry: boolean = false
   ) {}

packages/cli/test/cli/CLITest.ts

@@ -151,6 +151,24 @@ describe('CLI', function() {
     strictEqual(await readFile(processed, 'utf8'), '1;');
   });
 
+  it('ignores .d.ts files', async function() {
+    let ignored = await createTemporaryFile(
+      'a-dir/ignored.d.ts',
+      'export = 42;'
+    );
+    let { status, stdout, stderr } = await runCodemodCLI([dirname(ignored)]);
+
+    deepEqual(
+      { status, stdout, stderr },
+      {
+        status: 0,
+        stdout: `0 file(s), 0 modified, 0 errors\n`,
+        stderr: ''
+      }
+    );
+    strictEqual(await readFile(ignored, 'utf8'), 'export = 42;');
+  });
+
   it('processes files but does not replace their contents when using --dry', async function() {
     let afile = await createTemporaryFile('a-file.js', '3 + 4;');
     let { status, stdout, stderr } = await runCodemodCLI([