tests: unify all temporary files/folders under $VTMP/v, that can be cleaned by v wipe-cache (#15774)

cmd/tools/modules/testing/common.v

@@ -4,6 +4,7 @@ import os
 import time
 import term
 import benchmark
+import sync
 import sync.pool
 import v.pref
 import v.util.vtest
@@ -281,13 +282,17 @@ pub fn (mut ts TestSession) test() {
 	ts.append_message(.sentinel, '') // send the sentinel
 	_ := <-ts.nprint_ended // wait for the stop of the printing thread
 	eprintln(term.h_divider('-'))
+	ts.show_list_of_failed_tests()
 	// cleanup generated .tmp.c files after successful tests:
 	if ts.benchmark.nfail == 0 {
 		if ts.rm_binaries {
 			os.rmdir_all(ts.vtmp_dir) or {}
 		}
 	}
-	ts.show_list_of_failed_tests()
+	// remove empty session folders:
+	if os.ls(ts.vtmp_dir) or { [] }.len == 0 {
+		os.rmdir_all(ts.vtmp_dir) or {}
+	}
 }
 
 fn worker_trunner(mut p pool.PoolProcessor, idx int, thread_id int) voidptr {
@@ -343,10 +348,8 @@ fn worker_trunner(mut p pool.PoolProcessor, idx int, thread_id int) voidptr {
 	}
 	generated_binary_fpath := os.join_path_single(tmpd, generated_binary_fname)
 	if produces_file_output {
-		if os.exists(generated_binary_fpath) {
-			if ts.rm_binaries {
-				os.rm(generated_binary_fpath) or {}
-			}
+		if ts.rm_binaries {
+			os.rm(generated_binary_fpath) or {}
 		}
 
 		cmd_options << ' -o ${os.quoted_path(generated_binary_fpath)}'
@@ -439,7 +442,7 @@ fn worker_trunner(mut p pool.PoolProcessor, idx int, thread_id int) voidptr {
 			}
 		}
 	}
-	if produces_file_output && os.exists(generated_binary_fpath) && ts.rm_binaries {
+	if produces_file_output && ts.rm_binaries {
 		os.rm(generated_binary_fpath) or {}
 	}
 	return pool.no_result
@@ -571,7 +574,7 @@ pub fn header(msg string) {
 
 pub fn setup_new_vtmp_folder() string {
 	now := time.sys_mono_now()
-	new_vtmp_dir := os.join_path(os.temp_dir(), 'v', 'test_session_$now')
+	new_vtmp_dir := os.join_path(os.temp_dir(), 'v', 'tsession_${sync.thread_id().hex()}_$now')
 	os.mkdir_all(new_vtmp_dir) or { panic(err) }
 	os.setenv('VTMP', new_vtmp_dir, true)
 	return new_vtmp_dir

cmd/tools/test_if_v_test_system_works.v

@@ -26,13 +26,11 @@ fn get_vexe_path() string {
 }
 
 fn new_tdir() string {
-	tdir_ := os.join_path(os.temp_dir(), rand.ulid())
-	if os.exists(tdir_) {
-		os.rmdir(tdir_) or { panic(err) }
-	}
-	os.mkdir(tdir_) or { panic(err) }
+	dir := os.join_path(os.temp_dir(), 'v', rand.ulid())
+	os.rmdir_all(dir) or {}
+	os.mkdir_all(dir) or { panic(err) }
 	C.atexit(cleanup_tdir)
-	return tdir_
+	return dir
 }
 
 fn cleanup_tdir() {

cmd/tools/vbump_test.v

@@ -1,5 +1,17 @@
 import os
 
+const vexe = @VEXE
+
+const tfolder = os.join_path(os.temp_dir(), 'v', 'vbump')
+
+fn testsuite_begin() {
+	os.mkdir_all(tfolder) or {}
+}
+
+fn testsuite_end() {
+	os.rmdir_all(tfolder) or {}
+}
+
 struct BumpTestCase {
 	file_name      string
 	contents       string
@@ -62,10 +74,7 @@ fn main() {
 ]
 
 fn run_individual_test(case BumpTestCase) ? {
-	vexe := @VEXE
-
-	temp_dir := os.temp_dir()
-	test_file := os.join_path_single(temp_dir, case.file_name)
+	test_file := os.join_path_single(tfolder, case.file_name)
 
 	os.rm(test_file) or {}
 	os.write_file(test_file, case.contents)?

cmd/tools/vcheck-md.v

@@ -22,7 +22,7 @@ const (
 	show_progress                  = os.getenv('GITHUB_JOB') == '' && '-silent' !in os.args
 	non_option_args                = cmdline.only_non_options(os.args[2..])
 	is_verbose                     = os.getenv('VERBOSE') != ''
-	vcheckfolder                   = os.join_path_single(os.temp_dir(), 'vcheck_$os.getuid()')
+	vcheckfolder                   = os.join_path(os.temp_dir(), 'v', 'vcheck_$os.getuid()')
 )
 
 struct CheckResult {

cmd/tools/vcreate_test.v

@@ -1,6 +1,6 @@
 import os
 
-const test_path = 'vcreate_test'
+const test_path = os.join_path(os.temp_dir(), 'v', 'vcreate_test')
 
 fn init_and_check() ? {
 	os.execute_or_exit('${os.quoted_path(@VEXE)} init')
@@ -59,42 +59,27 @@ fn init_and_check() ? {
 	].join_lines()
 }
 
-fn test_v_init() ? {
-	dir := os.join_path(os.temp_dir(), test_path)
-	os.rmdir_all(dir) or {}
-	os.mkdir(dir) or {}
-	defer {
-		os.rmdir_all(dir) or {}
-	}
-	os.chdir(dir)?
+fn prepare_test_path() ? {
+	os.rmdir_all(test_path) or {}
+	os.mkdir_all(test_path) or {}
+	os.chdir(test_path)?
+}
 
+fn test_v_init() ? {
+	prepare_test_path()?
 	init_and_check()?
 }
 
 fn test_v_init_in_git_dir() ? {
-	dir := os.join_path(os.temp_dir(), test_path)
-	os.rmdir_all(dir) or {}
-	os.mkdir(dir) or {}
-	defer {
-		os.rmdir_all(dir) or {}
-	}
-	os.chdir(dir)?
+	prepare_test_path()?
 	os.execute_or_exit('git init .')
 	init_and_check()?
 }
 
 fn test_v_init_no_overwrite_gitignore() ? {
-	dir := os.join_path(os.temp_dir(), test_path)
-	os.rmdir_all(dir) or {}
-	os.mkdir(dir) or {}
-	os.write_file('$dir/.gitignore', 'blah')?
-	defer {
-		os.rmdir_all(dir) or {}
-	}
-	os.chdir(dir)?
-
+	prepare_test_path()?
+	os.write_file('.gitignore', 'blah')?
 	os.execute_or_exit('${os.quoted_path(@VEXE)} init')
-
 	assert os.read_file('.gitignore')? == 'blah'
 }
 
@@ -110,19 +95,15 @@ trim_trailing_whitespace = true
 indent_style = tab
 indent_size = 4
 '
-
-	dir := os.join_path(os.temp_dir(), test_path)
-	os.rmdir_all(dir) or {}
-	os.mkdir(dir) or {}
-	os.write_file('$dir/.gitattributes', git_attributes_content)?
-	os.write_file('$dir/.editorconfig', editor_config_content)?
-	defer {
-		os.rmdir_all(dir) or {}
-	}
-	os.chdir(dir)?
-
+	prepare_test_path()?
+	os.write_file('.gitattributes', git_attributes_content)?
+	os.write_file('.editorconfig', editor_config_content)?
 	os.execute_or_exit('${os.quoted_path(@VEXE)} init')
 
 	assert os.read_file('.gitattributes')? == git_attributes_content
 	assert os.read_file('.editorconfig')? == editor_config_content
 }
+
+fn testsuite_end() {
+	os.rmdir_all(test_path) or {}
+}

cmd/tools/vrepl.v

@@ -17,6 +17,7 @@ mut:
 	in_func  bool   // are we inside a new custom user function
 	line     string // the current line entered by the user
 	is_pin   bool   // does the repl 'pin' entered source code
+	folder   string // the folder in which the repl will write its temporary source files
 	//
 	modules         []string // all the import modules
 	alias           map[string]string // all the alias used in the import
@@ -35,22 +36,26 @@ const vexe = os.getenv('VEXE')
 
 const vstartup = os.getenv('VSTARTUP')
 
+const repl_folder = os.join_path(os.temp_dir(), 'v', 'repl')
+
 enum FnType {
 	@none
 	void
 	fn_type
 }
 
-fn new_repl() Repl {
+fn new_repl(folder string) Repl {
+	vstartup_source := os.read_file(vstartup) or { '' }.trim_right('\n\r').split_into_lines()
+	os.mkdir_all(folder) or {}
 	return Repl{
 		readline: readline.Readline{
 			skip_empty: true
 		}
+		folder: folder
 		modules: ['os', 'time', 'math']
-		vstartup_lines: os.read_file(vstartup) or { '' }.trim_right('\n\r').split_into_lines()
-		// Test file used to check if a function as a void return or a
-		// value return.
-		eval_func_lines: os.read_file(vstartup) or { '' }.trim_right('\n\r').split_into_lines()
+		vstartup_lines: vstartup_source
+		// Test file used to check if a function as a void return or a value return.
+		eval_func_lines: vstartup_source
 	}
 }
 
@@ -173,7 +178,7 @@ fn (r &Repl) current_source_code(should_add_temp_lines bool, not_add_print bool)
 // This function checks which one we have:
 fn (r &Repl) check_fn_type_kind(new_line string) FnType {
 	source_code := r.current_source_code(true, false) + '\nprintln($new_line)'
-	check_file := os.join_path(os.temp_dir(), '${rand.ulid()}.vrepl.check.v')
+	check_file := os.join_path(r.folder, '${rand.ulid()}.vrepl.check.v')
 	os.write_file(check_file, source_code) or { panic(err) }
 	defer {
 		os.rm(check_file) or {}
@@ -296,7 +301,7 @@ fn run_repl(workdir string, vrepl_prefix string) int {
 		}
 		cleanup_files([file, temp_file])
 	}
-	mut r := new_repl()
+	mut r := new_repl(workdir)
 	for {
 		if r.indent == 0 {
 			prompt = '>>> '
@@ -359,7 +364,7 @@ fn run_repl(workdir string, vrepl_prefix string) int {
 			continue
 		}
 		if r.line == 'reset' {
-			r = new_repl()
+			r = new_repl(workdir)
 			continue
 		}
 		if r.line == 'list' {
@@ -517,7 +522,7 @@ fn main() {
 	// so that the repl can be launched in parallel by several different
 	// threads by the REPL test runner.
 	args := cmdline.options_after(os.args, ['repl'])
-	replfolder := os.real_path(cmdline.option(args, '-replfolder', os.temp_dir()))
+	replfolder := os.real_path(cmdline.option(args, '-replfolder', repl_folder))
 	replprefix := cmdline.option(args, '-replprefix', 'noprefix.${rand.ulid()}.')
 	if !os.exists(os.getenv('VEXE')) {
 		println('Usage:')

cmd/tools/vwipe-cache.v

@@ -2,12 +2,18 @@ module main
 
 import os
 import v.vcache
+import v.util
 
 fn main() {
-	mut cm := vcache.new_cache_manager([])
-	cpath := cm.basepath
+	wipe_path(vcache.new_cache_manager([]).basepath, 'V cache')
+	wipe_path(util.get_vtmp_folder(), 'V tmp.c')
+	wipe_path(os.join_path(os.temp_dir(), 'v'), 'V tests')
+}
+
+fn wipe_path(cpath string, label string) {
 	if os.exists(cpath) && os.is_dir(cpath) {
 		os.rmdir_all(cpath) or {}
 	}
-	println('V cache folder $cpath was wiped.')
+	os.mkdir_all(cpath) or {}
+	println('$label folder $cpath was wiped.')
 }

vlib/net/unix/unix_test.v

@@ -1,7 +1,17 @@
 import os
 import net.unix
 
-const test_port = os.join_path(os.temp_dir(), 'unix_domain_socket')
+const tfolder = os.join_path(os.temp_dir(), 'v', 'unix_test')
+
+const test_port = os.join_path(tfolder, 'unix_domain_socket')
+
+fn testsuite_begin() {
+	os.mkdir_all(tfolder) or {}
+}
+
+fn testsuite_end() {
+	os.rmdir_all(tfolder) or {}
+}
 
 fn handle_conn(mut c unix.StreamConn) {
 	for {

vlib/net/unix/use_net_and_net_unix_together_test.v

@@ -5,7 +5,17 @@ import net
 // ensure that `net` is used, i.e. no warnings
 const use_net = net.no_timeout
 
-const test_port = os.join_path(os.temp_dir(), 'unix_domain_socket')
+const tfolder = os.join_path(os.temp_dir(), 'v', 'net_and_unix_together')
+
+const test_port = os.join_path(tfolder, 'unix_domain_socket')
+
+fn testsuite_begin() {
+	os.mkdir_all(tfolder) or {}
+}
+
+fn testsuite_end() {
+	os.rmdir_all(tfolder) or {}
+}
 
 fn test_that_net_and_net_unix_can_be_imported_together_without_conflicts() ? {
 	mut l := unix.listen_stream(test_port) or { panic(err) }

vlib/orm/orm_sql_or_blocks_test.v

@@ -6,7 +6,17 @@ struct User {
 	name string [unique]
 }
 
-const db_path = os.join_path(os.temp_dir(), 'sql_statement_or_blocks.db')
+const db_folder = os.join_path(os.temp_dir(), 'v', 'orm_sql')
+
+const db_path = os.join_path(db_folder, 'sql_statement_or_blocks.db')
+
+fn testsuite_begin() {
+	os.mkdir_all(db_folder) or {}
+}
+
+fn testsuite_end() {
+	os.rmdir_all(db_folder) or {}
+}
 
 fn test_ensure_db_exists_and_user_table_is_ok() ? {
 	mut db := sqlite.connect(db_path)?

vlib/os/os_test.v

@@ -106,7 +106,7 @@ fn test_create_file() ? {
 
 fn test_is_file() {
 	// Setup
-	work_dir := os.join_path_single(os.getwd(), 'is_file_test')
+	work_dir := os.join_path_single(tfolder, 'is_file_test')
 	os.mkdir_all(work_dir) or { panic(err) }
 	tfile := os.join_path_single(work_dir, 'tmp_file')
 	// Test things that shouldn't be a file
@@ -309,7 +309,7 @@ fn test_cp() {
 }
 
 fn test_mv() {
-	work_dir := os.join_path_single(os.getwd(), 'mv_test')
+	work_dir := os.join_path_single(tfolder, 'mv_test')
 	os.mkdir_all(work_dir) or { panic(err) }
 	// Setup test files
 	tfile1 := os.join_path_single(work_dir, 'file')
@@ -404,7 +404,7 @@ fn test_realpath_non_existing() {
 
 fn test_realpath_existing() {
 	existing_file_name := 'existing_file.txt'
-	existing_file := os.join_path_single(os.temp_dir(), existing_file_name)
+	existing_file := os.join_path_single(tfolder, existing_file_name)
 	os.rm(existing_file) or {}
 	os.write_file(existing_file, 'abc') or {}
 	assert os.exists(existing_file)

vlib/os/process_test.v

@@ -6,12 +6,14 @@ import time
 const (
 	vexe                   = os.getenv('VEXE')
 	vroot                  = os.dir(vexe)
-	test_os_process        = os.join_path(os.temp_dir(), 'v', 'test_os_process.exe')
+	tfolder                = os.join_path(os.temp_dir(), 'v', 'tests', 'os_process')
+	test_os_process        = os.join_path(tfolder, 'test_os_process.exe')
 	test_os_process_source = os.join_path(vroot, 'cmd/tools/test_os_process.v')
 )
 
 fn testsuite_begin() ? {
-	os.rm(test_os_process) or {}
+	os.rmdir_all(tfolder) or {}
+	os.mkdir_all(tfolder)?
 	if os.getenv('WINE_TEST_OS_PROCESS_EXE') != '' {
 		// Make it easier to run the test under wine emulation, by just
 		// prebuilding the executable with:
@@ -24,6 +26,10 @@ fn testsuite_begin() ? {
 	assert os.exists(test_os_process)
 }
 
+fn testsuite_end() ? {
+	os.rmdir_all(tfolder) or {}
+}
+
 fn test_getpid() {
 	pid := os.getpid()
 	eprintln('current pid: $pid')

vlib/stbi/stbi_test.v

@@ -1,6 +1,16 @@
 import os
 import stbi
 
+const tfolder = os.join_path(os.temp_dir(), 'v', 'stbi')
+
+fn testsuite_begin() {
+	os.mkdir_all(tfolder) or {}
+}
+
+fn testsuite_end() {
+	os.rmdir_all(tfolder) or {}
+}
+
 fn test_stbi_read_write() {
 	vroot := @VEXEROOT
 	path := os.join_path(vroot, 'examples', 'assets', 'logo.png')
@@ -8,7 +18,7 @@ fn test_stbi_read_write() {
 	d_s := stbi.load(path) or { panic(err) }
 	println('Image source data:\n $d_s')
 
-	out_path := os.join_path(os.temp_dir(), 'test.png')
+	out_path := os.join_path(tfolder, 'test.png')
 	println('Out path: $out_path')
 	stbi.stbi_write_png(out_path, d_s.width, d_s.height, 4, d_s.data, d_s.width * 4) or {
 		panic(err)

vlib/toml/tests/toml_test.v

@@ -68,7 +68,7 @@ fn test_toml() {
 }
 
 fn test_toml_file() {
-	out_path := os.join_path(os.temp_dir(), 'v_toml_tests')
+	out_path := os.join_path(os.temp_dir(), 'v', 'toml_tests')
 	test_file := os.join_path(out_path, 'toml_example.toml')
 	os.mkdir_all(out_path) or { assert false }
 	defer {

vlib/v/builder/builder_test.v

@@ -2,44 +2,44 @@ module main
 
 import os
 
-const test_path = 'v_run_check'
+const test_path = os.join_path(os.temp_dir(), 'v', 'run_check')
+
+const vexe = @VEXE
+
+fn testsuite_begin() {
+	os.mkdir_all(test_path) or {}
+}
+
+fn testsuite_end() {
+	os.rmdir_all(test_path) or {}
+}
 
 fn test_conditional_executable_removal() ? {
-	// Setup the sample project
-	dir := os.join_path(os.temp_dir(), test_path)
+	os.chdir(test_path)?
+	os.execute_or_exit('${os.quoted_path(vexe)} init')
 
-	os.rmdir_all(dir) or {}
-	os.mkdir(dir) or {}
-
-	defer {
-		os.rmdir_all(dir) or {}
-	}
-
-	os.chdir(dir)?
-	os.execute_or_exit('${os.quoted_path(@VEXE)} init')
-
-	mut executable := test_path
+	mut executable := 'run_check'
 	$if windows {
 		executable += '.exe'
 	}
 
-	original_file_list_ := os.ls(dir)?
+	original_file_list_ := os.ls(test_path)?
 	dump(original_file_list_)
 	assert executable !in original_file_list_
 
-	assert os.execute('${os.quoted_path(@VEXE)} run .').output.trim_space() == 'Hello World!'
-	after_run_file_list := os.ls(dir)?
+	assert os.execute('${os.quoted_path(vexe)} run .').output.trim_space() == 'Hello World!'
+	after_run_file_list := os.ls(test_path)?
 	dump(after_run_file_list)
 	assert executable !in after_run_file_list
 
-	assert os.execute('${os.quoted_path(@VEXE)} .').exit_code == 0
+	assert os.execute('${os.quoted_path(vexe)} .').exit_code == 0
 	assert os.execute('./$executable').output.trim_space() == 'Hello World!'
-	after_compilation__ := os.ls(dir)?
+	after_compilation__ := os.ls(test_path)?
 	dump(after_compilation__)
 	assert executable in after_compilation__
 
-	assert os.execute('${os.quoted_path(@VEXE)} run .').output.trim_space() == 'Hello World!'
-	after_second_run___ := os.ls(dir)?
+	assert os.execute('${os.quoted_path(vexe)} run .').output.trim_space() == 'Hello World!'
+	after_second_run___ := os.ls(test_path)?
 	dump(after_second_run___)
 	assert executable in after_second_run___
 }

vlib/v/builder/interpreterbuilder/v_interpret_test.v

@@ -9,7 +9,7 @@ fn interpreter_wrap(a string) string {
 }
 
 fn interp_test(expression string, expected string) ? {
-	tmpdir := os.join_path(os.temp_dir(), 'v_interpret_test_$rand.ulid()')
+	tmpdir := os.join_path(os.temp_dir(), 'v', 'interpret_test_$rand.ulid()')
 	os.mkdir_all(tmpdir) or {}
 	defer {
 		os.rmdir_all(tmpdir) or {}

vlib/v/gen/c/coutput_test.v

@@ -21,7 +21,7 @@ fn mm(s string) string {
 fn test_out_files() ? {
 	println(term.colorize(term.green, '> testing whether .out files match:'))
 	os.chdir(vroot) or {}
-	output_path := os.join_path(os.temp_dir(), 'coutput', 'out')
+	output_path := os.join_path(os.temp_dir(), 'v', 'coutput', 'out')
 	os.mkdir_all(output_path)?
 	defer {
 		os.rmdir_all(output_path) or {}
@@ -92,7 +92,7 @@ fn test_out_files() ? {
 fn test_c_must_have_files() ? {
 	println(term.colorize(term.green, '> testing whether `.c.must_have` files match:'))
 	os.chdir(vroot) or {}
-	output_path := os.join_path(os.temp_dir(), 'coutput', 'c_must_have')
+	output_path := os.join_path(os.temp_dir(), 'v', 'coutput', 'c_must_have')
 	os.mkdir_all(output_path)?
 	defer {
 		os.rmdir_all(output_path) or {}

vlib/v/gen/golang/tests/golang_test.v

@@ -19,8 +19,11 @@ fn test_golang() {
 	dir := os.join_path(vroot, 'vlib/v/gen/golang/tests')
 	files := os.ls(dir) or { panic(err) }
 	//
-	wrkdir := os.join_path(os.temp_dir(), 'vtests', 'golang')
+	wrkdir := os.join_path(os.temp_dir(), 'v', 'tests', 'golang')
 	os.mkdir_all(wrkdir) or { panic(err) }
+	defer {
+		os.rmdir_all(wrkdir) or {}
+	}
 	os.chdir(wrkdir) or {}
 	tests := files.filter(it.ends_with('.vv'))
 	if tests.len == 0 {

vlib/v/gen/js/jsgen_test.v

@@ -2,7 +2,7 @@ import os
 
 const (
 	test_dir     = os.join_path('vlib', 'v', 'gen', 'js', 'tests')
-	output_dir   = os.join_path(os.temp_dir(), '_js_tests/')
+	output_dir   = os.join_path(os.temp_dir(), 'v', '_js_tests/')
 	v_options    = '-b js -w'
 	node_options = ''
 )

vlib/v/gen/native/tests/native_test.v

@@ -20,8 +20,11 @@ fn test_native() {
 	dir := os.join_path(vroot, 'vlib/v/gen/native/tests')
 	files := os.ls(dir) or { panic(err) }
 	//
-	wrkdir := os.join_path(os.temp_dir(), 'vtests', 'native')
+	wrkdir := os.join_path(os.temp_dir(), 'v', 'tests', 'native')
 	os.mkdir_all(wrkdir) or { panic(err) }
+	defer {
+		os.rmdir_all(wrkdir) or {}
+	}
 	os.chdir(wrkdir) or {}
 	tests := files.filter(it.ends_with('.vv'))
 	if tests.len == 0 {

vlib/v/live/live_test.v

@@ -33,16 +33,15 @@ TODO: Cleanup this when/if v has better process control/communication primitives
 */
 const (
 	vexe                = os.getenv('VEXE')
-	tmp_file            = os.join_path(os.temp_dir(), 'generated_live_program.tmp.v')
-	source_file         = os.join_path(os.temp_dir(), 'generated_live_program.v')
-	genexe_file         = os.join_path(os.temp_dir(), 'generated_live_program')
-	output_file         = os.join_path(os.temp_dir(), 'generated_live_program.output.txt')
-	res_original_file   = os.join_path(os.temp_dir(), 'ORIGINAL.txt')
-	res_changed_file    = os.join_path(os.temp_dir(), 'CHANGED.txt')
-	res_another_file    = os.join_path(os.temp_dir(), 'ANOTHER.txt')
-	res_stop_file       = os.join_path(os.temp_dir(), 'STOP.txt')
-	cleanup_files       = [tmp_file, source_file, genexe_file, output_file, res_original_file,
-		res_changed_file, res_another_file, res_stop_file]
+	vtmp_folder         = os.join_path(os.temp_dir(), 'v', 'tests', 'live')
+	tmp_file            = os.join_path(vtmp_folder, 'generated_live_program.tmp.v')
+	source_file         = os.join_path(vtmp_folder, 'generated_live_program.v')
+	genexe_file         = os.join_path(vtmp_folder, 'generated_live_program')
+	output_file         = os.join_path(vtmp_folder, 'generated_live_program.output.txt')
+	res_original_file   = os.join_path(vtmp_folder, 'ORIGINAL.txt')
+	res_changed_file    = os.join_path(vtmp_folder, 'CHANGED.txt')
+	res_another_file    = os.join_path(vtmp_folder, 'ANOTHER.txt')
+	res_stop_file       = os.join_path(vtmp_folder, 'STOP.txt')
 	live_program_source = get_source_template()
 )
 
@@ -69,16 +68,14 @@ fn atomic_write_source(source string) {
 
 //
 fn testsuite_begin() {
+	os.rmdir_all(vtmp_folder) or {}
+	os.mkdir_all(vtmp_folder) or {}
 	if os.user_os() !in ['linux', 'solaris'] && os.getenv('FORCE_LIVE_TEST').len == 0 {
 		eprintln('Testing the runtime behaviour of -live mode,')
 		eprintln('is reliable only on Linux/macOS for now.')
 		eprintln('You can still do it by setting FORCE_LIVE_TEST=1 .')
 		exit(0)
 	}
-	for f in [tmp_file, source_file, output_file, res_original_file, res_changed_file,
-		res_another_file, res_stop_file] {
-		os.rm(f) or {}
-	}
 	atomic_write_source(live_program_source)
 }
 
@@ -106,9 +103,7 @@ fn testsuite_end() {
 	assert histogram['ORIGINAL'] > 0
 	assert histogram['CHANGED'] + histogram['ANOTHER'] > 0
 	// assert histogram['END'] > 0
-	for tfile in cleanup_files {
-		os.rm(tfile) or {}
-	}
+	os.rmdir_all(vtmp_folder) or {}
 }
 
 fn change_source(new string) {
@@ -120,7 +115,7 @@ fn change_source(new string) {
 
 fn wait_for_file(new string) {
 	time.sleep(100 * time.millisecond)
-	expected_file := os.join_path(os.temp_dir(), new + '.txt')
+	expected_file := os.join_path(vtmp_folder, new + '.txt')
 	eprintln('waiting for $expected_file ...')
 	max_wait_cycles := edefault('WAIT_CYCLES', '1').int()
 	for i := 0; i <= max_wait_cycles; i++ {

vlib/v/pref/options_test.v

@@ -5,6 +5,16 @@ import time
 
 const vexe = @VEXE
 
+const tfolder = os.join_path(os.temp_dir(), 'v', 'custom_compile')
+
+fn testsuite_begin() {
+	os.mkdir_all(tfolder) or {}
+}
+
+fn testsuite_end() {
+	os.rmdir_all(tfolder) or {}
+}
+
 fn test_cflags() ? {
 	os.chdir(os.real_path(@VMODROOT)) or {}
 	mut debug_arg := '-g3 -O0'
@@ -39,10 +49,10 @@ fn test_cflags() ? {
 
 fn custom_compile(fname string, cflags_options string) Results {
 	mut res := Results{}
-	res.exe = os.join_path(os.temp_dir(), fname)
+	res.exe = os.join_path(tfolder, fname)
 	res.sw = time.new_stopwatch()
 	res.compilation = os.execute('${os.quoted_path(vexe)} -cflags "$cflags_options" -o ${os.quoted_path(res.exe)} examples/hello_world.v')
-	res.delta = res.sw.elapsed().microseconds()
+	res.delta = res.sw.elapsed().milliseconds()
 	res.file_size = os.file_size(res.exe)
 	println('> $fname build took: $res.delta ms with "$cflags_options", file size: $res.file_size')
 	return res

vlib/v/tests/closure_generator_test.v

@@ -162,7 +162,7 @@ fn test_closure_return_${styp}_${i}() ? {
 
 	code := v_code.str()
 	println('Compiling V code (${code.count('\n')} lines) ...')
-	wrkdir := os.join_path(os.temp_dir(), 'vtests', 'closures')
+	wrkdir := os.join_path(os.temp_dir(), 'v', 'tests', 'closures')
 	os.mkdir_all(wrkdir)?
 	os.chdir(wrkdir)?
 	os.write_file('closure_return_test.v', code)?

vlib/v/tests/crun_mode/crun_test.v

@@ -1,7 +1,7 @@
 import os
 import time
 
-const crun_folder = os.join_path(os.temp_dir(), 'crun_folder')
+const crun_folder = os.join_path(os.temp_dir(), 'v', 'crun_folder')
 
 const vprogram_file = os.join_path(crun_folder, 'vprogram.vv')
 

vlib/v/tests/run_v_code_from_stdin_test.v

@@ -4,13 +4,19 @@ const vexe = os.getenv('VEXE')
 
 const turn_off_vcolors = os.setenv('VCOLORS', 'never', true)
 
+const vtmp_folder = os.join_path(os.temp_dir(), 'v', 'tests', 'run_v_code')
+
 fn test_vexe_is_set() {
 	assert vexe != ''
 }
 
 fn pipe_to_v_run() ? {
+	os.mkdir_all(vtmp_folder) or {}
+	defer {
+		os.rmdir_all(vtmp_folder) or {}
+	}
 	cat_cmd := if os.user_os() == 'windows' { 'cmd /c type' } else { 'cat' }
-	tmp_v_file := os.join_path(os.real_path(os.temp_dir()), 'generated_piped_program.v')
+	tmp_v_file := os.join_path(os.real_path(vtmp_folder), 'generated_piped_program.v')
 	// eprintln('>>> tmp_v_file: $tmp_v_file')
 	os.write_file(tmp_v_file, 'println(1 + 3)\nprintln("hello")\n')?
 	assert os.is_file(tmp_v_file)

vlib/v/tests/valgrind/valgrind_test.v

@@ -66,7 +66,7 @@ fn test_all() {
 	mut files := os.ls(dir) or { panic(err) }
 	files.sort()
 	//
-	wrkdir := os.join_path(os.temp_dir(), 'vtests', 'valgrind')
+	wrkdir := os.join_path(os.temp_dir(), 'v', 'tests', 'valgrind')
 	os.mkdir_all(wrkdir) or { panic(err) }
 	os.chdir(wrkdir) or {}
 	//
@@ -122,4 +122,5 @@ fn test_all() {
 	if bench.nfail > 0 {
 		exit(1)
 	}
+	os.rmdir_all(wrkdir) or {}
 }

vlib/v/vcache/vcache_test.v

@@ -2,7 +2,7 @@ import os
 import v.vcache
 
 const (
-	vcache_folder = os.join_path(os.temp_dir(), 'vcache_folder')
+	vcache_folder = os.join_path(os.temp_dir(), 'v', 'cache_folder')
 )
 
 fn check_cache_entry_fpath_invariants(x string, extension string) {

vlib/vweb/assets/assets_test.v

@@ -1,31 +1,31 @@
 import vweb.assets
 import os
 
+const base_cache_dir = os.join_path(os.temp_dir(), 'v', 'assets_test_cache')
+
+fn testsuite_begin() {
+	os.mkdir_all(base_cache_dir) or {}
+}
+
+fn testsuite_end() {
+	os.rmdir_all(base_cache_dir) or {}
+}
+
 // clean_cache_dir used before and after tests that write to a cache directory.
 // Because of parallel compilation and therefore test running,
 // unique cache dirs are needed per test function.
 fn clean_cache_dir(dir string) {
-	if os.is_dir(dir) {
-		os.rmdir_all(dir) or { panic(err) }
-	}
-}
-
-fn base_cache_dir() string {
-	return os.join_path(os.temp_dir(), 'assets_test_cache')
+	os.rmdir_all(dir) or {}
 }
 
 fn cache_dir(test_name string) string {
-	return os.join_path(base_cache_dir(), test_name)
+	return os.join_path(base_cache_dir, test_name)
 }
 
 fn get_test_file_path(file string) string {
-	path := os.join_path(base_cache_dir(), file)
-	if !os.is_dir(base_cache_dir()) {
-		os.mkdir_all(base_cache_dir()) or { panic(err) }
-	}
-	if !os.exists(path) {
-		os.write_file(path, get_test_file_contents(file)) or { panic(err) }
-	}
+	path := os.join_path(base_cache_dir, file)
+	os.rm(path) or {}
+	os.write_file(path, get_test_file_contents(file)) or { panic(err) }
 	return path
 }