tests: support VTEST_ONLY_FN=*test_sincos* ./v test . and ./v test -run-only test_sin .

vlib/v/gen/c/cmain.v

@@ -190,7 +190,8 @@ pub fn (mut g Gen) gen_c_main_for_tests() {
 	g.writeln('\tmain__vtest_init();')
 	g.writeln('\t_vinit(___argc, (voidptr)___argv);')
 	//
-	all_tfuncs := g.get_all_test_function_names()
+	mut all_tfuncs := g.get_all_test_function_names()
+	all_tfuncs = g.filter_only_matching_fn_names(all_tfuncs)
 	g.writeln('\tstring v_test_file = ${ctoslit(g.pref.path)};')
 	if g.pref.is_stats {
 		g.writeln('\tmain__BenchedTests bt = main__start_testing($all_tfuncs.len, v_test_file);')
@@ -248,3 +249,28 @@ pub fn (mut g Gen) gen_c_main_for_tests() {
 		println(g.out.after(main_fn_start_pos))
 	}
 }
+
+pub fn (mut g Gen) filter_only_matching_fn_names(fnames []string) []string {
+	if g.pref.run_only.len == 0 {
+		return fnames
+	}
+	mut res := []string{}
+	for tname in fnames {
+		if tname.contains('testsuite_') {
+			res << tname
+			continue
+		}
+		mut is_matching := false
+		for fn_glob_pattern in g.pref.run_only {
+			if tname.match_glob(fn_glob_pattern) {
+				is_matching = true
+				break
+			}
+		}
+		if !is_matching {
+			continue
+		}
+		res << tname
+	}
+	return res
+}

vlib/v/pref/pref.v

@@ -162,6 +162,8 @@ pub mut:
 	out_name         string
 	path             string // Path to file/folder to compile
 	// -d vfmt and -d another=0 for `$if vfmt { will execute }` and `$if another ? { will NOT get here }`
+	run_only []string // VTEST_ONLY_FN and -run-only accept comma separated glob patterns.
+	// Only test_ functions that match these patterns will be run. -run-only is valid only for _test.v files.
 	compile_defines     []string    // just ['vfmt']
 	compile_defines_all []string    // contains both: ['vfmt','another']
 	run_args            []string    // `v run x.v 1 2 3` => `1 2 3`
@@ -207,6 +209,7 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 	$if x64 {
 		res.m64 = true // follow V model by default
 	}
+	res.run_only = os.getenv('VTEST_ONLY_FN').split_any(',')
 	mut command := ''
 	mut command_pos := 0
 	// for i, arg in args {
@@ -466,6 +469,10 @@ pub fn parse_args_and_show_errors(known_external_commands []string, args []strin
 			'-show-depgraph' {
 				res.show_depgraph = true
 			}
+			'-run-only' {
+				res.run_only = cmdline.option(current_args, arg, os.getenv('VTEST_ONLY_FN')).split_any(',')
+				i++
+			}
 			'-test-runner' {
 				res.test_runner = cmdline.option(current_args, arg, res.test_runner)
 				i++