checker: add check against `fn test_opt() ?{}`

vlib/v/checker/checker.v

@@ -4505,16 +4505,21 @@ fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
 		}
 	}
 	// TODO c.pref.is_vet
-	if node.language == .v && !node.is_method && node.params.len == 0 && node.return_type == table.void_type_idx &&
-		node.name.after('.').starts_with('test_') && !c.file.path.ends_with('_test.v') {
-		// simple heuristic
-		for st in node.stmts {
-			if st is ast.AssertStmt {
-				c.warn('tests will not be run because filename does not end with `_test.v`',
-					node.pos)
-				break
+	if node.language == .v && !node.is_method && node.params.len == 0 && node.name.after('.').starts_with('test_') {
+		if !c.file.path.ends_with('_test.v') {
+			// simple heuristic
+			for st in node.stmts {
+				if st is ast.AssertStmt {
+					c.warn('tests will not be run, because filename does not end with `_test.v`',
+						node.pos)
+					break
+				}
 			}
 		}
+		// eprintln('> node.name: $node.name | node.return_type: $node.return_type')
+		if node.return_type != table.void_type_idx {
+			c.error('test functions should not return anything', node.pos)
+		}
 	}
 	c.expected_type = table.void_type
 	c.cur_fn = node

vlib/v/checker/tests/test_functions_should_not_return_test.out

@@ -0,0 +1,13 @@
+vlib/v/checker/tests/test_functions_should_not_return_test.vv:9:1: error: test functions should not return anything
+    7 | 
+    8 | // should be disallowed:
+    9 | fn test_returning_int() int {
+      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   10 | 
+   11 | }
+vlib/v/checker/tests/test_functions_should_not_return_test.vv:14:1: error: test functions should not return anything
+   12 | 
+   13 | // should be disallowed:
+   14 | fn test_returning_opt() ? {
+      | ~~~~~~~~~~~~~~~~~~~~~~~~~
+   15 | }

vlib/v/checker/tests/test_functions_should_not_return_test.vv

@@ -0,0 +1,15 @@
+// ordinary functions can return whatever they like,
+// since they are not called by V's testing system
+// in the generated main():
+fn abc() int {
+	return 1
+}
+
+// should be disallowed:
+fn test_returning_int() int {
+
+}
+
+// should be disallowed:
+fn test_returning_opt() ? {
+}

vlib/v/tests/run_v_code_from_stdin_test.v

@@ -8,7 +8,7 @@ fn test_vexe_is_set() {
 	assert vexe != ''
 }
 
-fn test_pipe_to_v_run() ? {
+fn pipe_to_v_run() ? {
 	cat_cmd := if os.user_os() == 'windows' { 'type' } else { 'cat' }
 	tmp_v_file := os.join_path(os.temp_dir(), 'generated_piped_program.v')
 	os.write_file(tmp_v_file, 'println(1 + 3)\nprintln("hello")\n') ?
@@ -21,3 +21,9 @@ fn test_pipe_to_v_run() ? {
 	os.rm(tmp_v_file)
 	assert !os.exists(tmp_v_file)
 }
+
+fn test_pipe_to_v_run() {
+	pipe_to_v_run() or {
+		panic(err)
+	}
+}

vlib/v/tests/unsafe_test.v

@@ -23,9 +23,7 @@ fn test_double_ptr() {
 		(*p) = &j
 		assert x == &j
 	}
-
-	/////////
-
+	// ///////
 	mut x := &int(0)
 	unsafe {
 		mut p := &x
@@ -60,7 +58,7 @@ fn test_if_expr_unsafe() {
 	assert *p == 4
 }
 
-fn test_unsafe_if_stmt() int {
+fn unsafe_if_stmt() int {
 	i := 4
 	unsafe {
 		if true {
@@ -70,6 +68,11 @@ fn test_unsafe_if_stmt() int {
 	return i
 }
 
+fn test_unsafe_if_stmt() {
+	x := unsafe_if_stmt()
+	assert x == 4
+}
+
 fn test_map_address_index() {
 	mut m := {
 		'one': 1

vlib/v/vcache/vcache_test.v

@@ -14,7 +14,7 @@ fn check_cache_entry_fpath_invariants(x string, extension string) {
 	assert a[1][0..2] == a[0]
 }
 
-fn testsuite_begin() ? {
+fn testsuite_begin() {
 	os.setenv('VCACHE', vcache_folder, true)
 	// eprintln('testsuite_begin, vcache_folder = $vcache_folder')
 	os.rmdir_all(vcache_folder)
@@ -22,41 +22,62 @@ fn testsuite_begin() ? {
 	assert os.is_dir(vcache_folder)
 }
 
-fn test_save_and_load() ? {
+fn test_save_and_load() {
 	mut cm := vcache.new_cache_manager([])
-	x := cm.save('.txt', 'first/cache/entry', 'hello') ?
+	x := cm.save('.txt', 'first/cache/entry', 'hello') or {
+		assert false
+		''
+	}
 	check_cache_entry_fpath_invariants(x, '.txt')
 }
 
-fn test_different_options_should_produce_different_cache_entries_for_same_key_and_content() ? {
+fn test_different_options_should_produce_different_cache_entries_for_same_key_and_content() {
 	mut cm1 := vcache.new_cache_manager([])
 	mut cm2 := vcache.new_cache_manager(['-cc tcc'])
 	mut cm3 := vcache.new_cache_manager(['-cc gcc'])
-	x := cm1.save('.txt', 'first/cache/entry', 'hello') ?
-	y := cm2.save('.txt', 'first/cache/entry', 'hello') ?
-	z := cm3.save('.txt', 'first/cache/entry', 'hello') ?
+	x := cm1.save('.txt', 'first/cache/entry', 'hello') or {
+		assert false
+		''
+	}
+	y := cm2.save('.txt', 'first/cache/entry', 'hello') or {
+		assert false
+		''
+	}
+	z := cm3.save('.txt', 'first/cache/entry', 'hello') or {
+		assert false
+		''
+	}
 	check_cache_entry_fpath_invariants(x, '.txt')
 	check_cache_entry_fpath_invariants(y, '.txt')
 	check_cache_entry_fpath_invariants(z, '.txt')
 }
 
-fn test_exists() ? {
+fn test_exists() {
 	mut cm := vcache.new_cache_manager([])
 	cm.exists('.o', 'abc') or {
 		assert true
 	}
 	//
-	x := cm.save('.x', 'abc', '') ?
+	x := cm.save('.x', 'abc', '') or {
+		assert false
+		''
+	}
 	cm.exists('.o', 'abc') or {
 		assert true
 	}
 	//
-	y := cm.save('.o', 'zbc', '') ?
+	y := cm.save('.o', 'zbc', '') or {
+		assert false
+		''
+	}
 	cm.exists('.o', 'abc') or {
 		assert true
 	}
 	//
-	z := cm.save('.o', 'abc', '') ?
+	z := cm.save('.o', 'abc', '') or {
+		assert false
+		''
+	}
 	cm.exists('.o', 'abc') or {
 		assert false
 	}
@@ -69,11 +90,14 @@ fn test_exists() ? {
 	assert y != z
 }
 
-fn test_readme_exists_and_is_readable() ? {
+fn test_readme_exists_and_is_readable() {
 	vcache.new_cache_manager([])
 	freadme := os.join_path(vcache_folder, 'README.md')
 	assert os.is_file(freadme)
-	x := os.read_file(freadme) ?
+	x := os.read_file(freadme) or {
+		assert false
+		''
+	}
 	assert x.len > 0
 	assert x.starts_with('This folder contains cached build artifacts')
 }

vlib/x/websocket/websocket_test.v

@@ -2,10 +2,12 @@ import x.websocket
 import time
 
 // Tests with external ws & wss servers
-fn test_ws() ? {
+fn test_ws() {
 	go start_server()
 	time.sleep_ms(100)
-	ws_test('ws://localhost:30000')?
+	ws_test('ws://localhost:30000') or {
+		assert false
+	}
 }
 
 fn start_server() ? {
@@ -20,7 +22,7 @@ fn start_server() ? {
 			return false
 		}
 		return true
-	})?
+	}) ?
 	s.on_message(fn (mut ws websocket.Client, msg &websocket.Message) ? {
 		// payload := if msg.payload.len == 0 { '' } else { string(msg.payload, msg.payload.len) }
 		// println('server client ($ws.id) got message: opcode: $msg.opcode, payload: $payload')
@@ -38,7 +40,7 @@ fn start_server() ? {
 
 fn ws_test(uri string) ? {
 	eprintln('connecting to $uri ...')
-	mut ws := websocket.new_client(uri)?
+	mut ws := websocket.new_client(uri) ?
 	ws.on_open(fn (mut ws websocket.Client) ? {
 		println('open!')
 		ws.pong()