fix parsing of null values in expressions: (#206)

* conditionals
* unary
* binary
* tuples
* singular

Author: kkozik-amplify

hcl2/transformer.py

@@ -52,7 +52,6 @@ def int_lit(self, args: List) -> int:
     def expr_term(self, args: List) -> Any:
         args = self.strip_new_line_tokens(args)
 
-        #
         if args[0] == "true":
             return True
         if args[0] == "false":
@@ -140,7 +139,7 @@ def provider_function_call(self, args: List) -> str:
         return f"{provider_func}({args_str})"
 
     def arguments(self, args: List) -> List:
-        return args
+        return self.process_nulls(args)
 
     @v_args(meta=True)
     def block(self, meta: Meta, args: List) -> Dict:
@@ -170,16 +169,19 @@ def attribute(self, args: List) -> Attribute:
 
     def conditional(self, args: List) -> str:
         args = self.strip_new_line_tokens(args)
+        args = self.process_nulls(args)
         return f"{args[0]} ? {args[1]} : {args[2]}"
 
     def binary_op(self, args: List) -> str:
         return " ".join([self.to_tf_inline(arg) for arg in args])
 
     def unary_op(self, args: List) -> str:
+        args = self.process_nulls(args)
         return "".join([self.to_tf_inline(arg) for arg in args])
 
     def binary_term(self, args: List) -> str:
         args = self.strip_new_line_tokens(args)
+        args = self.process_nulls(args)
         return " ".join([self.to_tf_inline(arg) for arg in args])
 
     def body(self, args: List) -> Dict[str, List]:
@@ -337,6 +339,9 @@ def process_escape_sequences(self, value: str) -> str:
             # for now, but this method can be extended in the future
         return value
 
+    def process_nulls(self, args: List) -> List:
+        return ["null" if arg is None else arg for arg in args]
+
     def to_tf_inline(self, value: Any) -> str:
         """
         Converts complex objects (e.g.) dicts to an "inline" HCL syntax

test/helpers/terraform-config-json/nulls.json

@@ -0,0 +1 @@
+{"terraform": {"unary": "${!null}", "binary": "${(a == null)}", "tuple": [null, 1, 2], "single": null, "conditional": "${null ? null : null}"}}

test/helpers/terraform-config/nulls.tf

@@ -0,0 +1,8 @@
+terraform = {
+  unary = !null
+  binary = (a == null)
+  tuple = [null, 1, 2]
+  single = null
+  conditional = null ? null : null
+
+}

test/unit/test_hcl2_syntax.py

@@ -119,7 +119,7 @@ def test_object(self):
                     "key4": "${true == false}",
                     "key5": "${5 + 5}",
                     "key6": "${function()}",
-                    "key7": "${value == None ? 1 : 0}",
+                    "key7": "${value == null ? 1 : 0}",
                 }
             },
         )
@@ -175,16 +175,16 @@ def test_null(self):
         result = self.load_to_dict(identifier)
         self.assertDictEqual(result, expected)
 
-    def test_expr_term_parentheses(self):
+    def test_expr_term_parenthesis(self):
         literals = {
             "a = 1 * 2 + 3": {"a": "${1 * 2 + 3}"},
             "b = 1 * (2 + 3)": {"b": "${1 * (2 + 3)}"},
             "c = (1 * (2 + 3))": {"c": "${(1 * (2 + 3))}"},
             "conditional = value == null ? 1 : 0": {
-                "conditional": "${value == None ? 1 : 0}"
+                "conditional": "${value == null ? 1 : 0}"
             },
             "conditional = (value == null ? 1 : 0)": {
-                "conditional": "${(value == None ? 1 : 0)}"
+                "conditional": "${(value == null ? 1 : 0)}"
             },
         }