Draft: TS-Migrate-Modules Codemod

codemods/typescript/migrate-modules/.mocharc.json

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+{
+	"loader": ["ts-node/esm"],
+	"full-trace": true,
+	"failZero": false,
+	"bail": true,
+	"spec": "./**/test.ts",
+	"timeout": 5000
+}

codemods/typescript/migrate-modules/config.json

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+{
+	"schemaVersion": "1.0.0",
+	"name": "typescript/migrate-modules",
+	"engine": "jscodeshift"
+}

codemods/typescript/migrate-modules/index.d.ts

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+import type { API, FileInfo } from 'jscodeshift';
+export default function transform(file: FileInfo, api: API): string;

codemods/typescript/migrate-modules/package.json

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+{
+	"name": "@codemod-registry/typescript-migrate-modules",
+	"dependencies": {},
+	"devDependencies": {
+		"@codemod-registry/tsconfig": "workspace:*",
+		"@codemod-registry/utilities": "workspace:*",
+		"@codemod-registry/cjs-builder": "workspace:*",
+		"typescript": "^5.2.2",
+		"esbuild": "0.19.5",
+		"ts-node": "^10.9.1",
+		"jscodeshift": "^0.15.1",
+		"@types/jscodeshift": "^0.11.10",
+		"vitest": "^1.0.1",
+		"@vitest/coverage-v8": "^1.0.1"
+	},
+	"main": "./dist/index.cjs",
+	"types": "/dist/index.d.ts",
+	"scripts": {
+		"build:cjs": "cjs-builder ./src/index.ts",
+		"test": "vitest run",
+		"test:watch": "vitest watch",
+		"coverage": "vitest run --coverage"
+	},
+	"files": [
+		"README.md",
+		"config.json",
+		"./dist/index.cjs",
+		"./index.d.ts"
+	],
+	"type": "module"
+}

codemods/typescript/migrate-modules/src/index.ts

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+import { API, FileInfo } from 'jscodeshift';
+
+export default function transformer(file: FileInfo, api: API) {
+	const j = api.jscodeshift;
+	const root = j(file.source);
+
+	root.find(j.TSModuleDeclaration).replaceWith((path) => {
+		const { node } = path;
+
+		if (node.body && node.body.type === 'TSModuleBlock') {
+			const body = node.body.body.map((declaration) => {
+				if (declaration.type === 'TSModuleDeclaration') {
+					return j.exportDeclaration(
+						[
+							j.exportSpecifier(
+								j.identifier(declaration.id.name),
+								j.identifier(declaration.id.name),
+							),
+						],
+						j.literal(null),
+						j.objectExpression([]),
+					);
+				} else {
+					return declaration;
+				}
+			});
+
+			return body;
+		}
+
+		return node;
+	});
+
+	root.find(j.TSImportEqualsDeclaration).replaceWith((path) => {
+		const { node } = path;
+		if (node.id.type === 'Identifier') {
+			return j.importDeclaration(
+			  [j.importNamespaceSpecifier(node.id)],
+			  j.literal(
+				node.moduleReference.type === 'TSExternalModuleReference'
+				  ? node.moduleReference.expression.value
+				  : null,
+			  ),
+			);
+		  }
+	});
+
+	root.find(j.TSExportAssignment).remove();
+
+	return root.toSource();
+}

codemods/typescript/migrate-modules/test/test.ts

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+import assert from 'node:assert';
+import { FileInfo } from 'jscodeshift';
+import { describe, it } from 'vitest';
+import transform from '../src/index';
+import { buildApi } from '@codemod-registry/utilities';
+
+describe('typescript migrate-modules', function () {
+	it('1', function () {
+		const INPUT = `
+            module Module1 {
+              export interface Person {
+                name: string;
+                age: number;
+              }
+
+              export function greet(person: Person): string {
+                return 'Hello';
+              }
+            }
+
+            export = Module1;
+        `;
+
+		const OUTPUT = `
+            export interface Person {
+              name: string;
+              age: number;
+            }
+
+            export function greet(person: Person): string {
+              return 'Hello';
+            }
+        `;
+
+		const fileInfo: FileInfo = {
+			path: 'index.js',
+			source: INPUT,
+		};
+
+		const actualOutput = transform(fileInfo, buildApi('tsx'));
+
+		assert.deepEqual(
+			actualOutput?.replace(/\W/gm, ''),
+			OUTPUT.replace(/\W/gm, ''),
+		);
+	});
+
+	it('2', function () {
+		const INPUT = `
+            module Module1 {
+              import Module2 = require('./Module2');
+
+              export interface Person {
+                name: string;
+                age: number;
+              }
+
+              export function greet(person: Person): string {
+                return 'Hello';
+              }
+
+              export function waveHands(): void {
+                Module2.wave();
+              }
+            }
+
+            export = Module1;
+        `;
+
+		const OUTPUT = `
+            import * as Module2 from './Module2';
+
+            export interface Person {
+              name: string;
+              age: number;
+            }
+
+            export function greet(person: Person): string {
+              return 'Hello';
+            }
+
+            export function waveHands(): void {
+              Module2.wave();
+            }
+        `;
+
+		const fileInfo: FileInfo = {
+			path: 'index.js',
+			source: INPUT,
+		};
+
+		const actualOutput = transform(fileInfo, buildApi('tsx'));
+
+		assert.deepEqual(
+			actualOutput?.replace(/\W/gm, ''),
+			OUTPUT.replace(/\W/gm, ''),
+		);
+	});
+
+	it('aliases', function () {
+		const INPUT = `
+            module Module1 {
+              import Module2 = require('./Module2');
+
+              export interface Person {
+                name: string;
+                age: number;
+              }
+
+              export function greet(person: Person): string {
+                return 'Hello';
+              }
+
+              export { Module2 as AliasModule };
+            }
+
+            export = Module1;
+        `;
+
+		const OUTPUT = `
+            import * as Module2 from './Module2';
+
+            export interface Person {
+              name: string;
+              age: number;
+            }
+
+            export function greet(person: Person): string {
+              return 'Hello';
+            }
+
+            export { Module2 as AliasModule };
+        `;
+
+		const fileInfo: FileInfo = {
+			path: 'index.js',
+			source: INPUT,
+		};
+
+		const actualOutput = transform(fileInfo, buildApi('tsx'));
+
+		assert.deepEqual(
+			actualOutput?.replace(/\W/gm, ''),
+			OUTPUT.replace(/\W/gm, ''),
+		);
+	});
+
+	it('nested', function () {
+		const INPUT = `
+            module Module1 {
+              module NestedModule {
+                export const constantValue = 42;
+              }
+
+              export { NestedModule };
+            }
+
+            export = Module1;
+        `;
+
+		const OUTPUT = `
+            export module NestedModule {
+              export const constantValue = 42;
+            }
+        `;
+
+		const fileInfo: FileInfo = {
+			path: 'index.js',
+			source: INPUT,
+		};
+
+		const actualOutput = transform(fileInfo, buildApi('tsx'));
+
+		assert.deepEqual(
+			actualOutput?.replace(/\W/gm, ''),
+			OUTPUT.replace(/\W/gm, ''),
+		);
+	});
+
+	it('Exporting and Importing Types', function () {
+		const INPUT = `
+            module MyModule {            
+              import SomeType = require('./SomeType');
+              export { SomeType };
+            }
+
+            export = MyModule;
+        `;
+
+		const OUTPUT = `
+            import * as SomeType from './SomeType';
+            export { SomeType };
+        `;
+
+		const fileInfo: FileInfo = {
+			path: 'index.js',
+			source: INPUT,
+		};
+
+		const actualOutput = transform(fileInfo, buildApi('tsx'));
+
+		assert.deepEqual(
+			actualOutput?.replace(/\W/gm, ''),
+			OUTPUT.replace(/\W/gm, ''),
+		);
+	});
+});

codemods/typescript/migrate-modules/tsconfig.json

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+{
+	"extends": "@codemod-registry/tsconfig",
+	"include": [
+		"./src/**/*.ts",
+		"./src/**/*.js",
+		"./test/**/*.ts",
+		"./test/**/*.js"
+	]
+}

codemods/typescript/recipe/config.json

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+{
+	"schemaVersion": "1.0.0",
+	"engine": "recipe",
+	"names": ["typescript/migrate-modules"]
+}

codemods/typescript/recipe/package.json

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+{
+	"name": "@codemod-registry/typescript-recipe",
+	"files": [
+		"README.md",
+		"config.json"
+	],
+	"type": "module"
+}