checker: report error for test functions that have parameters (#12500)

vlib/v/checker/checker.v

@@ -8298,7 +8298,7 @@ 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.is_test {
+	if node.language == .v && !node.is_method && node.is_test {
 		if !c.pref.is_test {
 			// simple heuristic
 			for st in node.stmts {
@@ -8309,6 +8309,10 @@ fn (mut c Checker) fn_decl(mut node ast.FnDecl) {
 				}
 			}
 		}
+
+		if node.params.len != 0 {
+			c.error('test functions should take 0 parameters', node.pos)
+		}
 		if node.return_type != ast.void_type_idx
 			&& node.return_type.clear_flag(.optional) != ast.void_type_idx {
 			c.error('test functions should either return nothing at all, or be marked to return `?`',

vlib/v/checker/tests/test_functions_should_not_return_test.out

@@ -1,7 +0,0 @@
-vlib/v/checker/tests/test_functions_should_not_return_test.vv:9:1: error: test functions should either return nothing at all, or be marked to return `?`
-    7 | 
-    8 | // should be disallowed:
-    9 | fn test_returning_int() int {
-      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~
-   10 | 
-   11 | }

vlib/v/checker/tests/test_functions_wrong_signature_test.out

@@ -0,0 +1,13 @@
+vlib/v/checker/tests/test_functions_wrong_signature_test.vv:9:1: error: test functions should either return nothing at all, or be marked to return `?`
+    7 | 
+    8 | // should be disallowed:
+    9 | fn test_returning_int() int {
+      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   10 | }
+   11 |
+vlib/v/checker/tests/test_functions_wrong_signature_test.vv:19:1: error: test functions should take 0 parameters
+   17 | 
+   18 | // should be disallowed:
+   19 | fn test_take_parameters(v int) {
+      | ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+   20 | }

vlib/v/checker/tests/test_functions_wrong_signature_test.vv

@@ -7,7 +7,6 @@ fn abc() int {
 
 // should be disallowed:
 fn test_returning_int() int {
-
 }
 
 // NB: this is allowed explicitly now, to allow for shorter tests
@@ -15,3 +14,7 @@ fn test_returning_int() int {
 fn test_returning_opt() ? {
 	assert true
 }
+
+// should be disallowed:
+fn test_take_parameters(v int) {
+}