RustPython · youknowone · Jan 17, 2026 · Jan 17, 2026 · Jan 17, 2026 · Jan 17, 2026
diff --git a/Lib/test/test_compiler_assemble.py b/Lib/test/test_compiler_assemble.py
@@ -0,0 +1,147 @@
+import dis
+import io
+import textwrap
+import types
+
+from test.support.bytecode_helper import AssemblerTestCase
+
+
+# Tests for the code-object creation stage of the compiler.
+
+class IsolatedAssembleTests(AssemblerTestCase):
+
+    def complete_metadata(self, metadata, filename="myfile.py"):
+        if metadata is None:
+            metadata = {}
+        for key in ['name', 'qualname']:
+            metadata.setdefault(key, key)
+        for key in ['consts']:
+            metadata.setdefault(key, [])
+        for key in ['names', 'varnames', 'cellvars', 'freevars', 'fasthidden']:
+            metadata.setdefault(key, {})
+        for key in ['argcount', 'posonlyargcount', 'kwonlyargcount']:
+            metadata.setdefault(key, 0)
+        metadata.setdefault('firstlineno', 1)
+        metadata.setdefault('filename', filename)
+        return metadata
+
+    def insts_to_code_object(self, insts, metadata):
+        metadata = self.complete_metadata(metadata)
+        seq = self.seq_from_insts(insts)
+        return self.get_code_object(metadata['filename'], seq, metadata)
+
+    def assemble_test(self, insts, metadata, expected):
+        co = self.insts_to_code_object(insts, metadata)
+        self.assertIsInstance(co, types.CodeType)
+
+        expected_metadata = {}
+        for key, value in metadata.items():
+            if key == "fasthidden":
+                # not exposed on code object
+                continue
+            if isinstance(value, list):
+                expected_metadata[key] = tuple(value)
+            elif isinstance(value, dict):
+                expected_metadata[key] = tuple(value.keys())
+            else:
+                expected_metadata[key] = value
+
+        for key, value in expected_metadata.items():
+            self.assertEqual(getattr(co, "co_" + key), value)
+
+        f = types.FunctionType(co, {})
+        for args, res in expected.items():
+            self.assertEqual(f(*args), res)
+
+    def test_simple_expr(self):
+        metadata = {
+            'filename' : 'avg.py',
+            'name'     : 'avg',
+            'qualname' : 'stats.avg',
+            'consts'   : {2 : 0},
+            'argcount' : 2,
+            'varnames' : {'x' : 0, 'y' : 1},
+        }
+
+        # code for "return (x+y)/2"
+        insts = [
+            ('RESUME', 0),
+            ('LOAD_FAST', 0, 1),   # 'x'
+            ('LOAD_FAST', 1, 1),   # 'y'
+            ('BINARY_OP', 0, 1),   # '+'
+            ('LOAD_CONST', 0, 1),  # 2
+            ('BINARY_OP', 11, 1),   # '/'
+            ('RETURN_VALUE', None, 1),
+        ]
+        expected = {(3, 4) : 3.5, (-100, 200) : 50, (10, 18) : 14}
+        self.assemble_test(insts, metadata, expected)
+
+
+    def test_expression_with_pseudo_instruction_load_closure(self):
+
+        def mod_two(x):
+            def inner():
+                return x
+            return inner() % 2
+
+        inner_code = mod_two.__code__.co_consts[1]
+        assert isinstance(inner_code, types.CodeType)
+
+        metadata = {
+            'filename' : 'mod_two.py',
+            'name'     : 'mod_two',
+            'qualname' : 'nested.mod_two',
+            'cellvars' : {'x' : 0},
+            'consts': {None: 0, inner_code: 1, 2: 2},
+            'argcount' : 1,
+            'varnames' : {'x' : 0},
+        }
+
+        instructions = [
+            ('RESUME', 0,),
+            ('LOAD_CLOSURE', 0, 1),
+            ('BUILD_TUPLE', 1, 1),
+            ('LOAD_CONST', 1, 1),
+            ('MAKE_FUNCTION', None, 2),
+            ('SET_FUNCTION_ATTRIBUTE', 8, 2),
+            ('PUSH_NULL', None, 1),
+            ('CALL', 0, 2),                     # (lambda: x)()
+            ('LOAD_CONST', 2, 2),               # 2
+            ('BINARY_OP', 6, 2),                # %
+            ('RETURN_VALUE', None, 2)
+        ]
+
+        expected = {(0,): 0, (1,): 1, (2,): 0, (120,): 0, (121,): 1}
+        self.assemble_test(instructions, metadata, expected)
+
+
+    def test_exception_table(self):
+        metadata = {
+            'filename' : 'exc.py',
+            'name'     : 'exc',
+            'consts'   : {2 : 0},
+        }
+
+        # code for "try: pass\n except: pass"
+        insts = [
+            ('RESUME', 0),
+            ('SETUP_FINALLY', 3),
+            ('RETURN_CONST', 0),
+            ('SETUP_CLEANUP', 8),
+            ('PUSH_EXC_INFO', None),
+            ('POP_TOP', None),
+            ('POP_EXCEPT', None),
+            ('RETURN_CONST', 0),
+            ('COPY', 3),
+            ('POP_EXCEPT', None),
+            ('RERAISE', 1),
+        ]
+        co = self.insts_to_code_object(insts, metadata)
+        output = io.StringIO()
+        dis.dis(co, file=output)
+        exc_table = textwrap.dedent("""
+                                       ExceptionTable:
+                                         L1 to L2 -> L2 [0]
+                                         L2 to L3 -> L3 [1] lasti
+                                    """)
+        self.assertTrue(output.getvalue().endswith(exc_table))
diff --git a/Lib/test/test_compiler_codegen.py b/Lib/test/test_compiler_codegen.py
@@ -0,0 +1,159 @@
+
+import textwrap
+from test.support.bytecode_helper import CodegenTestCase
+
+# Tests for the code-generation stage of the compiler.
+# Examine the un-optimized code generated from the AST.
+
+class IsolatedCodeGenTests(CodegenTestCase):
+
+    def assertInstructionsMatch_recursive(self, insts, expected_insts):
+        expected_nested = [i for i in expected_insts if isinstance(i, list)]
+        expected_insts = [i for i in expected_insts if not isinstance(i, list)]
+        self.assertInstructionsMatch(insts, expected_insts)
+        self.assertEqual(len(insts.get_nested()), len(expected_nested))
+        for n_insts, n_expected in zip(insts.get_nested(), expected_nested):
+            self.assertInstructionsMatch_recursive(n_insts, n_expected)
+
+    def codegen_test(self, snippet, expected_insts):
+        import ast
+        a = ast.parse(snippet, "my_file.py", "exec")
+        insts = self.generate_code(a)
+        self.assertInstructionsMatch_recursive(insts, expected_insts)
+
+    def test_if_expression(self):
+        snippet = "42 if True else 24"
+        false_lbl = self.Label()
+        expected = [
+            ('RESUME', 0, 0),
+            ('LOAD_CONST', 0, 1),
+            ('TO_BOOL', 0, 1),
+            ('POP_JUMP_IF_FALSE', false_lbl := self.Label(), 1),
+            ('LOAD_CONST', 1, 1),
+            ('JUMP_NO_INTERRUPT', exit_lbl := self.Label()),
+            false_lbl,
+            ('LOAD_CONST', 2, 1),
+            exit_lbl,
+            ('POP_TOP', None),
+            ('LOAD_CONST', 3),
+            ('RETURN_VALUE', None),
+        ]
+        self.codegen_test(snippet, expected)
+
+    def test_for_loop(self):
+        snippet = "for x in l:\n\tprint(x)"
+        false_lbl = self.Label()
+        expected = [
+            ('RESUME', 0, 0),
+            ('LOAD_NAME', 0, 1),
+            ('GET_ITER', None, 1),
+            loop_lbl := self.Label(),
+            ('FOR_ITER', exit_lbl := self.Label(), 1),
+            ('NOP', None, 1, 1),
+            ('STORE_NAME', 1, 1),
+            ('LOAD_NAME', 2, 2),
+            ('PUSH_NULL', None, 2),
+            ('LOAD_NAME', 1, 2),
+            ('CALL', 1, 2),
+            ('POP_TOP', None),
+            ('JUMP', loop_lbl),
+            exit_lbl,
+            ('END_FOR', None),
+            ('POP_TOP', None),
+            ('LOAD_CONST', 0),
+            ('RETURN_VALUE', None),
+        ]
+        self.codegen_test(snippet, expected)
+
+    def test_function(self):
+        snippet = textwrap.dedent("""
+            def f(x):
+                return x + 42
+        """)
+        expected = [
+            # Function definition
+            ('RESUME', 0),
+            ('LOAD_CONST', 0),
+            ('MAKE_FUNCTION', None),
+            ('STORE_NAME', 0),
+            ('LOAD_CONST', 1),
+            ('RETURN_VALUE', None),
+            [
+                # Function body
+                ('RESUME', 0),
+                ('LOAD_FAST', 0),
+                ('LOAD_CONST', 1),
+                ('BINARY_OP', 0),
+                ('RETURN_VALUE', None),
+                ('LOAD_CONST', 0),
+                ('RETURN_VALUE', None),
+            ]
+        ]
+        self.codegen_test(snippet, expected)
+
+    def test_nested_functions(self):
+        snippet = textwrap.dedent("""
+            def f():
+                def h():
+                    return 12
+                def g():
+                    x = 1
+                    y = 2
+                    z = 3
+                    u = 4
+                    return 42
+        """)
+        expected = [
+            # Function definition
+            ('RESUME', 0),
+            ('LOAD_CONST', 0),
+            ('MAKE_FUNCTION', None),
+            ('STORE_NAME', 0),
+            ('LOAD_CONST', 1),
+            ('RETURN_VALUE', None),
+            [
+                # Function body
+                ('RESUME', 0),
+                ('LOAD_CONST', 1),
+                ('MAKE_FUNCTION', None),
+                ('STORE_FAST', 0),
+                ('LOAD_CONST', 2),
+                ('MAKE_FUNCTION', None),
+                ('STORE_FAST', 1),
+                ('LOAD_CONST', 0),
+                ('RETURN_VALUE', None),
+                [
+                    ('RESUME', 0),
+                    ('NOP', None),
+                    ('LOAD_CONST', 1),
+                    ('RETURN_VALUE', None),
+                    ('LOAD_CONST', 0),
+                    ('RETURN_VALUE', None),
+                ],
+                [
+                    ('RESUME', 0),
+                    ('LOAD_CONST', 1),
+                    ('STORE_FAST', 0),
+                    ('LOAD_CONST', 2),
+                    ('STORE_FAST', 1),
+                    ('LOAD_CONST', 3),
+                    ('STORE_FAST', 2),
+                    ('LOAD_CONST', 4),
+                    ('STORE_FAST', 3),
+                    ('NOP', None),
+                    ('LOAD_CONST', 5),
+                    ('RETURN_VALUE', None),
+                    ('LOAD_CONST', 0),
+                    ('RETURN_VALUE', None),
+                ],
+            ],
+        ]
+        self.codegen_test(snippet, expected)
+
+    def test_syntax_error__return_not_in_function(self):
+        snippet = "return 42"
+        with self.assertRaisesRegex(SyntaxError, "'return' outside function") as cm:
+            self.codegen_test(snippet, None)
+        self.assertIsNone(cm.exception.text)
+        self.assertEqual(cm.exception.offset, 1)
+        self.assertEqual(cm.exception.end_offset, 10)