Refactor tests (better grouping + cocotb support) (#15)

* initial refactor

* fix cocotb tests

* fix typecheck

* install verilator

tests/body/test_struct_body.py

@@ -0,0 +1,59 @@
+from peakrdl_busdecoder.body import StructBody
+
+
+class TestStructBody:
+    """Test the StructBody class."""
+
+    def test_simple_struct(self) -> None:
+        """Test simple struct definition."""
+        body = StructBody("my_struct_t", packed=True, typedef=True)
+        body += "logic [7:0] field1;"
+        body += "logic field2;"
+
+        result = str(body)
+        assert "typedef struct packed" in result
+        assert "my_struct_t" in result
+        assert "logic [7:0] field1;" in result
+        assert "logic field2;" in result
+
+    def test_unpacked_struct(self) -> None:
+        """Test unpacked struct definition."""
+        body = StructBody("unpacked_t", packed=False, typedef=True)
+        body += "int field1;"
+
+        result = str(body)
+        assert "typedef struct" in result
+        assert "packed" not in result or "typedef struct {" in result
+        assert "unpacked_t" in result
+
+    def test_struct_without_typedef(self) -> None:
+        """Test struct without typedef."""
+        body = StructBody("my_struct", packed=True, typedef=False)
+        body += "logic field;"
+
+        result = str(body)
+        # When typedef=False, packed is not used
+        assert "struct {" in result
+        assert "typedef" not in result
+        assert "my_struct" in result
+
+    def test_empty_struct(self) -> None:
+        """Test empty struct."""
+        body = StructBody("empty_t", packed=True, typedef=True)
+        result = str(body)
+        assert "typedef struct packed" in result
+        assert "empty_t" in result
+
+    def test_nested_struct(self) -> None:
+        """Test struct with nested struct."""
+        outer = StructBody("outer_t", packed=True, typedef=True)
+        inner = StructBody("inner_t", packed=True, typedef=True)
+        inner += "logic field1;"
+        outer += "logic field2;"
+        outer += str(inner)  # Include inner struct as a string
+
+        result = str(outer)
+        assert "outer_t" in result
+        assert "field2;" in result
+        # Inner struct should appear in the string
+        assert "inner_t" in result