diff --git a/doc/docs.md b/doc/docs.md
index ba6c2cfd73..829d76f461 100644
--- a/doc/docs.md
+++ b/doc/docs.md
@@ -2823,7 +2823,7 @@ fn C.sqlite3_step(&sqlite3_stmt)
 
 fn C.sqlite3_finalize(&sqlite3_stmt)
 
-fn C.sqlite3_exec(db &sqlite3, sql charptr, FnSqlite3Callback voidptr, cb_arg voidptr, emsg &charptr) int
+fn C.sqlite3_exec(db &sqlite3, sql charptr, cb FnSqlite3Callback, cb_arg voidptr, emsg &charptr) int
 
 fn C.sqlite3_free(voidptr)
 
diff --git a/vlib/v/compiler_errors_test.v b/vlib/v/compiler_errors_test.v
index 1c97c1b59a..699dde33c1 100644
--- a/vlib/v/compiler_errors_test.v
+++ b/vlib/v/compiler_errors_test.v
@@ -7,12 +7,13 @@ import sync
 import runtime
 import benchmark
 
-const (
-	skip_files     = [
+const skip_files = [
 		'vlib/v/checker/tests/custom_comptime_define_if_flag.vv',
 	]
-	should_autofix = os.getenv('VAUTOFIX') != ''
-)
+
+const turn_off_vcolors = os.setenv('VCOLORS', 'never', true)
+
+const should_autofix = os.getenv('VAUTOFIX') != ''
 
 struct TaskDescription {
 	vexe             string
@@ -21,12 +22,12 @@ struct TaskDescription {
 	result_extension string
 	path             string
 mut:
-	is_error         bool
-	is_skipped       bool
-	is_module        bool
-	expected         string
-	found___         string
-	took             time.Duration
+	is_error   bool
+	is_skipped bool
+	is_module  bool
+	expected   string
+	found___   string
+	took       time.Duration
 }
 
 fn test_all() {
@@ -138,7 +139,9 @@ fn (mut tasks []TaskDescription) run() {
 	bench.stop()
 	eprintln(term.h_divider('-'))
 	eprintln(bench.total_message('all tests'))
-	assert total_errors == 0
+	if total_errors != 0 {
+		exit(1)
+	}
 }
 
 // a single worker thread spends its time getting work from the `work` channel,
@@ -192,7 +195,7 @@ fn clean_line_endings(s string) string {
 
 fn diff_content(s1 string, s2 string) {
 	diff_cmd := util.find_working_diff_command() or { return }
-	println('diff: ')
+	println(term.bold(term.yellow('diff: ')))
 	println(util.color_compare_strings(diff_cmd, s1, s2))
 	println('============\n')
 }
diff --git a/vlib/v/tests/inout/compiler_test.v b/vlib/v/tests/inout/compiler_test.v
index 73f22bf2cb..23668fcfc6 100644
--- a/vlib/v/tests/inout/compiler_test.v
+++ b/vlib/v/tests/inout/compiler_test.v
@@ -3,32 +3,28 @@ import term
 import v.util
 import v.util.vtest
 
+const turn_off_vcolors = os.setenv('VCOLORS', 'never', true)
+
 fn test_all() {
 	mut total_errors := 0
 	vexe := os.getenv('VEXE')
 	vroot := os.dir(vexe)
 	os.chdir(vroot)
-	diff_cmd := util.find_working_diff_command() or {
-		''
-	}
+	diff_cmd := util.find_working_diff_command() or { '' }
 	dir := 'vlib/v/tests/inout'
-	files := os.ls(dir) or {
-		panic(err)
-	}
+	files := os.ls(dir) or { panic(err) }
 	tests := files.filter(it.ends_with('.vv'))
 	if tests.len == 0 {
 		println('no compiler tests found')
 		assert false
 	}
-	paths := vtest.filter_vtest_only(tests, {
+	paths := vtest.filter_vtest_only(tests, 
 		basepath: dir
-	})
+	)
 	for path in paths {
 		print(path + ' ')
 		program := path
-		compilation := os.exec('$vexe -o test -cflags "-w" -cg $program') or {
-			panic(err)
-		}
+		compilation := os.exec('$vexe -o test -cflags "-w" -cg $program') or { panic(err) }
 		if compilation.exit_code != 0 {
 			panic('compilation failed: $compilation.output')
 		}
@@ -49,9 +45,7 @@ fn test_all() {
 		// println(res.output)
 		// println('============')
 		mut found := res.output.trim_right('\r\n').replace('\r\n', '\n')
-		mut expected := os.read_file(program.replace('.vv', '') + '.out') or {
-			panic(err)
-		}
+		mut expected := os.read_file(program.replace('.vv', '') + '.out') or { panic(err) }
 		expected = expected.trim_right('\r\n').replace('\r\n', '\n')
 		if expected.contains('================ V panic ================') {
 			// panic include backtraces and absolute file paths, so can't do char by char comparison
diff --git a/vlib/v/tests/multiple_paths_in_vmodules/vmodules_overrides_test.v b/vlib/v/tests/multiple_paths_in_vmodules/vmodules_overrides_test.v
index e5c528b49f..9d8d336d9e 100644
--- a/vlib/v/tests/multiple_paths_in_vmodules/vmodules_overrides_test.v
+++ b/vlib/v/tests/multiple_paths_in_vmodules/vmodules_overrides_test.v
@@ -1,11 +1,14 @@
 import os
 
-const (
-	vexe = os.getenv('VEXE')
-	vroot = os.dir(vexe)
-	basepath = os.real_path(os.join_path(vroot, 'vlib', 'v', 'tests', 'multiple_paths_in_vmodules'))
-	mainvv = os.join_path(basepath, 'main.vv')
-)
+const turn_off_vcolors = os.setenv('VCOLORS', 'never', true)
+
+const vexe = os.getenv('VEXE')
+
+const vroot = os.dir(vexe)
+
+const basepath = os.real_path(os.join_path(vroot, 'vlib', 'v', 'tests', 'multiple_paths_in_vmodules'))
+
+const mainvv = os.join_path(basepath, 'main.vv')
 
 fn test_vexe_is_set() {
 	assert vexe != ''
@@ -15,20 +18,16 @@ fn test_vexe_is_set() {
 fn test_compiling_without_vmodules_fails() {
 	os.chdir(vroot)
 	os.setenv('VMODULES', '', true)
-	res := os.exec('"$vexe" run "$mainvv"') or {
-		panic(err)
-	}
+	res := os.exec('"$vexe" run "$mainvv"') or { panic(err) }
 	assert res.exit_code == 1
 	assert res.output.trim_space() == 'builder error: cannot import module "yyy" (not found)'
 }
 
 fn test_compiling_with_vmodules_works() {
-	os.chdir(vroot)	
-	vmpaths := ['path1', 'path2', 'path3'].map(os.join_path(basepath, it))	
+	os.chdir(vroot)
+	vmpaths := ['path1', 'path2', 'path3'].map(os.join_path(basepath, it))
 	os.setenv('VMODULES', vmpaths.join(os.path_delimiter), true)
-	res := os.exec('"$vexe" run "$mainvv"') or {
-		panic(err)
-	}
+	res := os.exec('"$vexe" run "$mainvv"') or { panic(err) }
 	assert res.exit_code == 0
 	assert res.output.trim_space() == "['x', 'y', 'z']"
 }
diff --git a/vlib/v/tests/repl/repl_test.v b/vlib/v/tests/repl/repl_test.v
index 2c7a65cdae..b600f09513 100644
--- a/vlib/v/tests/repl/repl_test.v
+++ b/vlib/v/tests/repl/repl_test.v
@@ -5,20 +5,18 @@ import v.tests.repl.runner
 import benchmark
 import sync
 
+const turn_off_vcolors = os.setenv('VCOLORS', 'never', true)
+
 fn test_the_v_compiler_can_be_invoked() {
 	vexec := runner.full_path_to_v(5)
 	println('vexecutable: $vexec')
 	assert vexec != ''
 	vcmd := '"$vexec" -version'
-	r := os.exec(vcmd) or {
-		panic(err)
-	}
+	r := os.exec(vcmd) or { panic(err) }
 	// println('"$vcmd" exit_code: $r.exit_code | output: $r.output')
 	assert r.exit_code == 0
 	vcmd_error := '"$vexec" nonexisting.v'
-	r_error := os.exec(vcmd_error) or {
-		panic(err)
-	}
+	r_error := os.exec(vcmd_error) or { panic(err) }
 	// println('"$vcmd_error" exit_code: $r_error.exit_code | output: $r_error.output')
 	assert r_error.exit_code == 1
 	actual_error := r_error.output.trim_space()
@@ -41,9 +39,9 @@ fn test_all_v_repl_files() {
 		panic(err)
 	}
 	session.bmark.set_total_expected_steps(session.options.files.len)
-	mut pool_repl := sync.new_pool_processor({
+	mut pool_repl := sync.new_pool_processor(
 		callback: worker_repl
-	})
+	)
 	pool_repl.set_shared_context(session)
 	$if windows {
 		// See: https://docs.microsoft.com/en-us/cpp/build/reference/fs-force-synchronous-pdb-writes?view=vs-2019
@@ -64,13 +62,11 @@ fn worker_repl(mut p sync.PoolProcessor, idx int, thread_id int) voidptr {
 		p.set_thread_context(idx, tls_bench)
 	}
 	tls_bench.cstep = idx
-	tfolder := os.join_path(cdir,'vrepl_tests_$idx')
+	tfolder := os.join_path(cdir, 'vrepl_tests_$idx')
 	if os.is_dir(tfolder) {
 		os.rmdir_all(tfolder)
 	}
-	os.mkdir(tfolder) or {
-		panic(err)
-	}
+	os.mkdir(tfolder) or { panic(err) }
 	file := p.get_string_item(idx)
 	session.bmark.step()
 	tls_bench.step()
diff --git a/vlib/v/tests/run_v_code_from_stdin_test.v b/vlib/v/tests/run_v_code_from_stdin_test.v
index 171dc232a0..3c16ec85dd 100644
--- a/vlib/v/tests/run_v_code_from_stdin_test.v
+++ b/vlib/v/tests/run_v_code_from_stdin_test.v
@@ -1,8 +1,8 @@
 import os
 
-const (
-	vexe = os.getenv('VEXE')
-)
+const vexe = os.getenv('VEXE')
+
+const turn_off_vcolors = os.setenv('VCOLORS', 'never', true)
 
 fn test_vexe_is_set() {
 	assert vexe != ''
@@ -24,7 +24,5 @@ fn pipe_to_v_run() ? {
 }
 
 fn test_pipe_to_v_run() {
-	pipe_to_v_run() or {
-		panic(err)
-	}
+	pipe_to_v_run() or { panic(err) }
 }
diff --git a/vlib/v/tests/valgrind/valgrind_test.v b/vlib/v/tests/valgrind/valgrind_test.v
index a0af9738b9..066ca512dd 100644
--- a/vlib/v/tests/valgrind/valgrind_test.v
+++ b/vlib/v/tests/valgrind/valgrind_test.v
@@ -4,6 +4,8 @@ import benchmark
 import v.util
 import v.util.vtest
 
+const turn_off_vcolors = os.setenv('VCOLORS', 'never', true)
+
 //
 // NB: skip_compile_files can be used for totally skipping .v files temporarily.
 // .v files in skip_valgrind_files will be compiled, but will not be run under
@@ -14,17 +16,16 @@ import v.util.vtest
 // Use: `./v -d noskip vlib/v/tests/valgrind/valgrind_test.v` to ignore skip_valgrind_files
 // Use: `./v -d noskipcompile -d noskip vlib/v/tests/valgrind/valgrind_test.v` to ignore both
 //
-const (
-	skip_compile_files  = [
+const skip_compile_files = [
 		'vlib/v/tests/valgrind/option_reassigned.v',
 	]
-	skip_valgrind_files = [
+
+const skip_valgrind_files = [
 		'vlib/v/tests/valgrind/struct_field.v',
 		'vlib/v/tests/valgrind/fn_returning_string_param.v',
 		'vlib/v/tests/valgrind/fn_with_return_should_free_local_vars.v',
 		'vlib/v/tests/valgrind/option_simple.v',
 	]
-)
 
 fn vprintln(s string) {
 	$if verbose ? {
@@ -49,18 +50,16 @@ fn test_all() {
 	vroot := os.dir(vexe)
 	valgrind_test_path := 'vlib/v/tests/valgrind'
 	dir := os.join_path(vroot, valgrind_test_path)
-	files := os.ls(dir) or {
-		panic(err)
-	}
+	files := os.ls(dir) or { panic(err) }
 	//
 	wrkdir := os.join_path(os.temp_dir(), 'vtests', 'valgrind')
 	os.mkdir_all(wrkdir)
 	os.chdir(wrkdir)
 	//
 	tests := vtest.filter_vtest_only(files.filter(it.ends_with('.v') && !it.ends_with('_test.v')),
-		{
+		
 		basepath: valgrind_test_path
-	})
+	)
 	bench.set_total_expected_steps(tests.len)
 	for test in tests {
 		bench.step()