feat: --watch mode

Closes: #5

README.md

@@ -70,6 +70,8 @@ Just use `"test": "exodus-test"`
 
 - `--coverage-engine node` -- use Node.js builtint coverage engine
 
+- `--watch` -- operate in watch mode and re-run tests on file changes
+
 - `--passWithNoTests` -- do not error when no test files were found
 
 - `--write-snapshots` -- write snapshots instead of verifying them (has `--test-update-snapshots` alias)

bin/index.js

@@ -26,9 +26,10 @@ function parseOptions() {
     esbuild: false,
     babel: false,
     coverage: false,
+    coverageEngine: 'c8', // c8 or node
+    watch: false,
     passWithNoTests: false,
     writeSnapshots: false,
-    coverageEngine: 'c8', // c8 or node
   }
 
   const args = [...process.argv]
@@ -63,6 +64,9 @@ function parseOptions() {
       case '--coverage':
         options.coverage = true
         break
+      case '--watch':
+        options.watch = true
+        break
       case '--passWithNoTests':
         options.passWithNoTests = true
         break
@@ -120,6 +124,11 @@ if (options.forceExit) {
   args.push('--test-force-exit')
 }
 
+if (options.watch) {
+  assert((major === 18 && minor > 13) || major >= 20, 'For watch mode, use Node.js >= 18.13.0')
+  args.push('--watch')
+}
+
 if (options.coverage) {
   if (options.coverageEngine === 'node') {
     args.push('--experimental-test-coverage')