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

* initial refactor

* fix cocotb tests

* fix typecheck

* install verilator

tests/body/test_body.py

@@ -0,0 +1,50 @@
+
+from peakrdl_busdecoder.body import Body
+
+
+class TestBody:
+    """Test the base Body class."""
+
+    def test_empty_body(self) -> None:
+        """Test empty body returns empty string."""
+        body = Body()
+        assert str(body) == ""
+        assert not body  # Should be falsy when empty
+
+    def test_add_single_line(self) -> None:
+        """Test adding a single line to body."""
+        body = Body()
+        body += "line1"
+        assert str(body) == "line1"
+        assert body  # Should be truthy when not empty
+
+    def test_add_multiple_lines(self) -> None:
+        """Test adding multiple lines to body."""
+        body = Body()
+        body += "line1"
+        body += "line2"
+        body += "line3"
+        expected = "line1\nline2\nline3"
+        assert str(body) == expected
+
+    def test_add_returns_self(self) -> None:
+        """Test that add operation returns self for chaining."""
+        body = Body()
+        body += "line1"
+        body += "line2"
+        # Chaining works because += returns self
+        assert len(body.lines) == 2
+
+    def test_add_nested_body(self) -> None:
+        """Test adding another body as a line."""
+        outer = Body()
+        inner = Body()
+        inner += "inner1"
+        inner += "inner2"
+        outer += "outer1"
+        outer += inner
+        outer += "outer2"
+        expected = "outer1\ninner1\ninner2\nouter2"
+        assert str(outer) == expected
+
+