From 3f2ccf41016307dd25190bd60808ced860614ba6 Mon Sep 17 00:00:00 2001
From: LordBaryhobal <lordbaryhobal@gmail.com>
Date: Thu, 9 Jul 2026 19:05:04 +0200
Subject: [PATCH] tests: add test covering some function subtyping rules

---
 tests/cases/checker/11_function_subtyping.py  |  44 +++
 .../checker/11_function_subtyping.py.ref.json | 282 ++++++++++++++++++
 tests/checker.py                              |   3 +
 3 files changed, 329 insertions(+)
 create mode 100644 tests/cases/checker/11_function_subtyping.py
 create mode 100644 tests/cases/checker/11_function_subtyping.py.ref.json

diff --git a/tests/cases/checker/11_function_subtyping.py b/tests/cases/checker/11_function_subtyping.py
new file mode 100644
index 0000000..86119c9
--- /dev/null
+++ b/tests/cases/checker/11_function_subtyping.py
@@ -0,0 +1,44 @@
+def a1(param: int) -> float: ...
+def a2(param: float) -> int: ...
+
+
+a = a1
+a = a2
+
+
+def b1(a: int, /) -> float: ...
+def b2(b: float, /) -> int: ...
+
+
+b = b1
+b = b2
+
+
+def c1(a: int) -> None: ...
+def c2(p: float = 0, /, *, a: float = 0) -> None: ...
+
+
+c = c1
+c = c2
+
+# Invalid subtypes
+
+
+def d1(a: int) -> float: ...
+def d2(a: str) -> float: ...
+def d3(a: int) -> str: ...
+
+
+d = d1
+d = d2
+d = d3
+
+
+def e1(*, a: int = 0) -> None: ...
+def e2(*, a: int) -> None: ...
+def e3(*, a: int = 0, b: int) -> None: ...
+
+
+e = e1
+e = e2
+e = e3
diff --git a/tests/cases/checker/11_function_subtyping.py.ref.json b/tests/cases/checker/11_function_subtyping.py.ref.json
new file mode 100644
index 0000000..b39b2a8
--- /dev/null
+++ b/tests/cases/checker/11_function_subtyping.py.ref.json
@@ -0,0 +1,282 @@
+{
+  "diagnostics": [
+    {
+      "type": "Warning",
+      "location": {
+        "start": [
+          1,
+          29
+        ],
+        "end": [
+          1,
+          32
+        ]
+      },
+      "message": "Unknown literal LiteralExpr(location=Location(lineno=1, col_offset=29, end_lineno=1, end_col_offset=32), value=Ellipsis)"
+    },
+    {
+      "type": "Error",
+      "location": {
+        "start": [
+          1,
+          22
+        ],
+        "end": [
+          1,
+          27
+        ]
+      },
+      "message": "Return type mismatch, annotated float but returns None"
+    },
+    {
+      "type": "Warning",
+      "location": {
+        "start": [
+          2,
+          29
+        ],
+        "end": [
+          2,
+          32
+        ]
+      },
+      "message": "Unknown literal LiteralExpr(location=Location(lineno=2, col_offset=29, end_lineno=2, end_col_offset=32), value=Ellipsis)"
+    },
+    {
+      "type": "Error",
+      "location": {
+        "start": [
+          2,
+          24
+        ],
+        "end": [
+          2,
+          27
+        ]
+      },
+      "message": "Return type mismatch, annotated int but returns None"
+    },
+    {
+      "type": "Warning",
+      "location": {
+        "start": [
+          9,
+          28
+        ],
+        "end": [
+          9,
+          31
+        ]
+      },
+      "message": "Unknown literal LiteralExpr(location=Location(lineno=9, col_offset=28, end_lineno=9, end_col_offset=31), value=Ellipsis)"
+    },
+    {
+      "type": "Error",
+      "location": {
+        "start": [
+          9,
+          21
+        ],
+        "end": [
+          9,
+          26
+        ]
+      },
+      "message": "Return type mismatch, annotated float but returns None"
+    },
+    {
+      "type": "Warning",
+      "location": {
+        "start": [
+          10,
+          28
+        ],
+        "end": [
+          10,
+          31
+        ]
+      },
+      "message": "Unknown literal LiteralExpr(location=Location(lineno=10, col_offset=28, end_lineno=10, end_col_offset=31), value=Ellipsis)"
+    },
+    {
+      "type": "Error",
+      "location": {
+        "start": [
+          10,
+          23
+        ],
+        "end": [
+          10,
+          26
+        ]
+      },
+      "message": "Return type mismatch, annotated int but returns None"
+    }
+  ],
+  "judgments": [
+    {
+      "location": {
+        "from": "L1:29",
+        "to": "L1:32"
+      },
+      "expr": {
+        "_type": "LiteralExpr",
+        "value": "..."
+      },
+      "type": {}
+    },
+    {
+      "location": {
+        "from": "L2:29",
+        "to": "L2:32"
+      },
+      "expr": {
+        "_type": "LiteralExpr",
+        "value": "..."
+      },
+      "type": {}
+    },
+    {
+      "location": {
+        "from": "L5:4",
+        "to": "L5:6"
+      },
+      "expr": {
+        "_type": "VariableExpr",
+        "name": "a1"
+      },
+      "type": {
+        "params": {
+          "pos": [],
+          "mixed": [
+            {
+              "pos": 0,
+              "name": "param",
+              "type": {
+                "name": "int"
+              },
+              "required": true,
+              "unsupported": false
+            }
+          ],
+          "kw": []
+        },
+        "returns": {
+          "name": "float"
+        }
+      }
+    },
+    {
+      "location": {
+        "from": "L6:4",
+        "to": "L6:6"
+      },
+      "expr": {
+        "_type": "VariableExpr",
+        "name": "a2"
+      },
+      "type": {
+        "params": {
+          "pos": [],
+          "mixed": [
+            {
+              "pos": 0,
+              "name": "param",
+              "type": {
+                "name": "float"
+              },
+              "required": true,
+              "unsupported": false
+            }
+          ],
+          "kw": []
+        },
+        "returns": {
+          "name": "int"
+        }
+      }
+    },
+    {
+      "location": {
+        "from": "L9:28",
+        "to": "L9:31"
+      },
+      "expr": {
+        "_type": "LiteralExpr",
+        "value": "..."
+      },
+      "type": {}
+    },
+    {
+      "location": {
+        "from": "L10:28",
+        "to": "L10:31"
+      },
+      "expr": {
+        "_type": "LiteralExpr",
+        "value": "..."
+      },
+      "type": {}
+    },
+    {
+      "location": {
+        "from": "L13:4",
+        "to": "L13:6"
+      },
+      "expr": {
+        "_type": "VariableExpr",
+        "name": "b1"
+      },
+      "type": {
+        "params": {
+          "pos": [
+            {
+              "pos": 0,
+              "name": "a",
+              "type": {
+                "name": "int"
+              },
+              "required": true,
+              "unsupported": false
+            }
+          ],
+          "mixed": [],
+          "kw": []
+        },
+        "returns": {
+          "name": "float"
+        }
+      }
+    },
+    {
+      "location": {
+        "from": "L14:4",
+        "to": "L14:6"
+      },
+      "expr": {
+        "_type": "VariableExpr",
+        "name": "b2"
+      },
+      "type": {
+        "params": {
+          "pos": [
+            {
+              "pos": 0,
+              "name": "b",
+              "type": {
+                "name": "float"
+              },
+              "required": true,
+              "unsupported": false
+            }
+          ],
+          "mixed": [],
+          "kw": []
+        },
+        "returns": {
+          "name": "int"
+        }
+      }
+    }
+  ]
+}
\ No newline at end of file
diff --git a/tests/checker.py b/tests/checker.py
index 2b591e7..7a630c5 100644
--- a/tests/checker.py
+++ b/tests/checker.py
@@ -18,6 +18,9 @@ class CustomEncoder(json.JSONEncoder):
             return ast.dump(o)
         if isinstance(o, TokenType):
             return o.name
+        if o == ...:
+            return "..."
+
         return super().default(o)