tests(checker): add control flow test

tests/cases/checker/05_control_flow.py

@@ -0,0 +1,25 @@
+def valid(a: int, b: int) -> int:
+    return a + b
+
+def with_if(a: int, b: int) -> int:
+    if a < b:
+        return b - a
+    else:
+        return a - b
+
+def unreachable1():
+    return
+    a = 0
+
+def unreachable2(a: int) -> int:
+    if a > 10:
+        return a - 10
+    else:
+        return a
+    b = 0
+
+def mixed(a: int, b: int):
+    if a < b:
+        return b - a
+    else:
+        return "oops"

tests/cases/checker/05_control_flow.py.ref.json

@@ -0,0 +1,46 @@
+{
+  "diagnostics": [
+    {
+      "type": "Warning",
+      "location": {
+        "start": [
+          12,
+          4
+        ],
+        "end": [
+          12,
+          9
+        ]
+      },
+      "message": "Unreachable statement"
+    },
+    {
+      "type": "Warning",
+      "location": {
+        "start": [
+          19,
+          4
+        ],
+        "end": [
+          19,
+          9
+        ]
+      },
+      "message": "Unreachable statement"
+    },
+    {
+      "type": "Error",
+      "location": {
+        "start": [
+          21,
+          0
+        ],
+        "end": [
+          25,
+          21
+        ]
+      },
+      "message": "Mixed return types: [BaseType(name='int'), BaseType(name='str')]"
+    }
+  ]
+}

tests/serializer/python.py

@@ -15,6 +15,7 @@ from midas.ast.python import (
     FrameType,
     Function,
     GetExpr,
+    IfStmt,
     LiteralExpr,
     LogicalExpr,
     MidasType,
@@ -164,6 +165,14 @@ class PythonAstJsonSerializer(
             "value": self._serialize_optional(stmt.value),
         }
 
+    def visit_if_stmt(self, stmt: IfStmt) -> dict:
+        return {
+            "_type": "IfStmt",
+            "test": stmt.test.accept(self),
+            "body": self._serialize_list(stmt.body),
+            "orelse": self._serialize_list(stmt.orelse),
+        }
+
     def visit_binary_expr(self, expr: BinaryExpr) -> dict:
         return {
             "_type": "BinaryExpr",