tests: support `VTEST_ONLY=parser ./v vlib/v/compiler_errors_test.v`

cmd/tools/modules/testing/common.v

@@ -69,6 +69,7 @@ pub fn (mut ts TestSession) test() {
 	//
 	ts.init()
 	mut remaining_files := []string{}
+	vtest_only := os.getenv('VTEST_ONLY')
 	for dot_relative_file in ts.files {
 		relative_file := dot_relative_file.replace('./', '')
 		file := os.real_path(relative_file)
@@ -92,6 +93,11 @@ pub fn (mut ts TestSession) test() {
 				continue
 			}
 		}
+		if vtest_only.len > 0 {
+			if !file.contains(vtest_only) {
+				continue
+			}
+		}
 		remaining_files << dot_relative_file
 	}
 	ts.files = remaining_files

vlib/v/compiler_errors_test.v

@@ -33,9 +33,19 @@ fn get_tests_in_dir(dir string) []string {
 }
 
 fn check_path(vexe, dir, voptions, result_extension string, tests []string) int {
+	vtest_only := os.getenv('VTEST_ONLY')
 	mut nb_fail := 0
+	mut paths := []string{}
 	for test in tests {
 		path := os.join_path(dir, test).replace('\\', '/')
+		if vtest_only.len > 0 {
+			if !path.contains(vtest_only) {
+				continue
+			}
+		}
+		paths << path
+	}
+	for path in paths {
 		program := path.replace('.vv', '.v')
 		print(path + ' ')
 		os.cp(path, program) or {
@@ -68,5 +78,10 @@ fn check_path(vexe, dir, voptions, result_extension string, tests []string) int
 }
 
 fn clean_line_endings(s string) string {
-	return s.trim_space().replace(' \n', '\n').replace(' \r\n', '\n').replace('\r\n', '\n').trim('\n')
+	mut res := s.trim_space()
+	res = res.replace(' \n', '\n')
+	res = res.replace(' \r\n', '\n')
+	res = res.replace('\r\n', '\n')
+	res = res.trim('\n')
+	return res
 }