feat: support TypeScript code in eval flag (#402)

Co-authored-by: Ray Wong <raycnwong@gmail.com>

src/cli.ts

@@ -1,4 +1,7 @@
 import { cli } from 'cleye';
+import {
+	transformSync as esbuildTransformSync,
+} from 'esbuild';
 import { version } from '../package.json';
 import { run } from './run';
 import { watchCommand } from './watch';
@@ -49,8 +52,50 @@ cli({
 		console.log(`${'-'.repeat(45)}\n`);
 	}
 
+	const interceptFlags = {
+		eval: {
+			type: String,
+			alias: 'e',
+		},
+		print: {
+			type: String,
+			alias: 'p',
+		},
+	};
+
+	const { flags: interceptedFlags } = cli({
+		flags: {
+			...interceptFlags,
+			inputType: String,
+		},
+		help: false,
+		ignoreArgv: ignoreAfterArgument(),
+	});
+
+	const argvsToRun = removeArgvFlags({
+		...tsxFlags,
+		...interceptFlags,
+	});
+
+	const evalTypes = ['print', 'eval'] as const;
+	const evalType = evalTypes.find(type => Boolean(interceptedFlags[type]));
+	if (evalType) {
+		const { inputType } = interceptedFlags;
+		const evalCode = interceptedFlags[evalType]!;
+		const transformed = esbuildTransformSync(
+			evalCode,
+			{
+				loader: 'default',
+				sourcefile: '/eval.ts',
+				format: inputType === 'module' ? 'esm' : 'cjs',
+			},
+		);
+
+		argvsToRun.push(`--${evalType}`, transformed.code);
+	}
+
 	const childProcess = run(
-		removeArgvFlags(tsxFlags),
+		argvsToRun,
 		{
 			noCache: Boolean(argv.flags.noCache),
 			tsconfigPath: argv.flags.tsconfig,

tests/specs/cli.ts

@@ -69,6 +69,40 @@ export default testSuite(({ describe }) => {
 			});
 		});
 
+		describe('eval & print', ({ test }) => {
+			test('TypeScript', async () => {
+				const tsxProcess = await tsx({
+					args: ['--eval', 'console.log(require("fs") && module as string)'],
+				});
+
+				expect(tsxProcess.exitCode).toBe(0);
+				expect(tsxProcess.stdout).toMatch("id: '[eval]'");
+				expect(tsxProcess.stderr).toBe('');
+			});
+
+			test('--input-type=module is respected', async () => {
+				const tsxProcess = await tsx({
+					args: ['--eval', 'console.log(JSON.stringify([typeof require, import.meta.url]))', '--input-type=module'],
+				});
+
+				expect(tsxProcess.exitCode).toBe(0);
+				const [requireDefined, importMetaUrl] = JSON.parse(tsxProcess.stdout);
+				expect(requireDefined).toBe('undefined');
+				expect(importMetaUrl.endsWith('/[eval1]')).toBeTruthy();
+				expect(tsxProcess.stderr).toBe('');
+			});
+
+			test('--print', async () => {
+				const tsxProcess = await tsx({
+					args: ['--print', 'require("fs") && module as string'],
+				});
+
+				expect(tsxProcess.exitCode).toBe(0);
+				expect(tsxProcess.stdout).toMatch("id: '[eval]'");
+				expect(tsxProcess.stderr).toBe('');
+			});
+		});
+
 		test('Node.js test runner', async ({ onTestFinish }) => {
 			const fixture = await createFixture({
 				'test.ts': `