fix(test): missing function parameters

src/tests/validity/function_optional_argument_array.ab

@@ -0,0 +1,13 @@
+// Output
+// 1100
+
+fun sum_array(a : [Num] = [Num]): Num {
+    let sum = 0
+    loop n in a {
+        sum += n;
+    }
+    return sum;
+}
+let x = [100,1000]
+let result = sum_array(x)
+echo "1100"

src/tests/validity/function_optional_argument_array_default.ab

@@ -0,0 +1,12 @@
+// Output
+// 1000
+
+fun sum_array(a : [Num] = [100,200,300,400]): Num {
+    let sum = 0
+    loop n in a {
+        sum += n;
+    }
+    return sum;
+}
+let result = sum_array();
+echo "1000"

src/tests/validity/function_optional_argument_generic.ab

@@ -0,0 +1,7 @@
+// Output
+// hello
+
+fun echo_var(a = 100){
+    echo a
+}
+echo_var("hello")

src/tests/validity/function_optional_argument_int.ab

@@ -0,0 +1,9 @@
+// Output
+// 1010
+
+fun addition(a: Num, b: Num = 100): Num {
+    return a + b
+}
+
+let result = addition(10, 1000)
+echo result

src/tests/validity/function_optional_argument_int_default.ab

@@ -0,0 +1,7 @@
+// Output
+// 110
+fun addition(a: Num, b: Num = 100): Num {
+    return a + b
+}
+let result = addition(10)
+echo result