add tests, rebase for cleaner PR commit overview

vlib/v/pref/pref_test.v

@@ -1,8 +1,40 @@
 module pref
 
+import v.vmod
+import os
+
 fn test_check_parametes() {
 	// reproducing issue https://github.com/vlang/v/issues/13983
 	_, cmd := parse_args_and_show_errors(['help'], [''], true)
 	// no command found from args
 	assert cmd == ''
 }
+
+fn test_version_falg() {
+	// Vars instead of consts to prevent dupl decls in pref.
+	vexe := @VEXE
+	vroot := os.dir(vexe)
+
+	v_ver := vmod.from_file(os.join_path(vroot, 'v.mod'))!.version
+	v_ver_cmd_res := os.execute_opt('${vexe} --version')!.output
+	assert v_ver_cmd_res.starts_with('V ${v_ver}'), v_ver_cmd_res
+
+	v_retry_ver_cmd_res := os.execute_opt('${vexe} retry --version')!.output
+	assert v_retry_ver_cmd_res != v_ver_cmd_res
+
+	v_git_ver_subcmd_res := os.execute_opt('${vexe} retry -- git --version')!.output
+	assert v_git_ver_subcmd_res !in [v_ver_cmd_res, v_retry_ver_cmd_res]
+
+	// Test version / verbosity toggle.
+	assert os.execute_opt('${vexe} -v')!.output == v_ver_cmd_res
+	assert os.execute_opt('${vexe} -cc tcc -v')!.output == v_ver_cmd_res
+
+	example_path := os.join_path(vroot, 'examples', 'hello_world.v')
+	v_verbose_cmd_res := os.execute_opt('${vexe} -v run ${example_path}')!.output
+	assert v_verbose_cmd_res != v_ver_cmd_res
+	assert v_verbose_cmd_res.contains('v.pref.lookup_path:')
+
+	v_verbose_cmd_with_additional_args_res := os.execute_opt('${vexe} -cc tcc -v run ${example_path}')!.output
+	assert v_verbose_cmd_with_additional_args_res != v_ver_cmd_res
+	assert v_verbose_cmd_with_additional_args_res.contains('v.pref.lookup_path:')
+}