tests: add new test for #16519 (#16520)

Author: yuyi98

vlib/v/tests/sumtype_with_alias_fntype_fn_call_test.v

@@ -0,0 +1,44 @@
+struct None {}
+
+type Myfn = fn (int) int
+
+type Myfnfact = fn () Myfn
+
+type Maybefnfact = Myfnfact | None
+
+// Myfn
+fn abc(i int) int {
+	return i
+}
+
+// create Myfn
+fn myfnfact() Myfn {
+	return abc
+}
+
+// run fn if exists
+fn run(mmff Maybefnfact) string {
+	match mmff {
+		Myfnfact {
+			r := mmff()
+			return 'yes fn: ${r}'
+		}
+		None {
+			return 'None fn'
+		}
+	}
+}
+
+fn test_sumtype_with_alias_fntype_fn_call() {
+	r1 := main.myfnfact()(1)
+	println(r1)
+	assert r1 == 1
+
+	r2 := run(None{})
+	println(r2)
+	assert r2 == 'None fn'
+
+	r3 := run(myfnfact)
+	println(r3)
+	assert r3 == 'yes fn: fn (int) int'
+}

vlib/v/tests/sumtype_with_alias_fntype_test.v

@@ -11,25 +11,18 @@ fn abc(i int) int {
 	return i
 }
 
-// create Myfn
-fn myfnfact() Myfn {
-	return abc
-}
-
-// run fn if exists
 fn run(mmff Maybefnfact) string {
 	match mmff {
-		Myfnfact {
-			r := mmff()
-			return 'yes fn: ${r}'
-		}
-		None {
-			return 'None fn'
-		}
+		Myfnfact { return 'yes fn' }
+		None { return 'None fn' }
 	}
 }
 
 fn test_sumtype_with_alias_fntype() {
+	// create Myfn
+	myfnfact := fn () Myfn {
+		return abc
+	}
 	r1 := main.myfnfact()(1)
 	println(r1)
 	assert r1 == 1
@@ -40,5 +33,5 @@ fn test_sumtype_with_alias_fntype() {
 
 	r3 := run(myfnfact)
 	println(r3)
-	assert r3 == 'yes fn: fn (int) int'
+	assert r3 == 'yes fn'
 }