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

* initial refactor

* fix cocotb tests

* fix typecheck

* install verilator

tests/body/test_combinational_body.py

@@ -0,0 +1,39 @@
+from peakrdl_busdecoder.body import CombinationalBody, IfBody
+
+
+class TestCombinationalBody:
+    """Test the CombinationalBody class."""
+
+    def test_simple_combinational_block(self) -> None:
+        """Test simple combinational block."""
+        body = CombinationalBody()
+        body += "assign1 = value1;"
+        body += "assign2 = value2;"
+
+        result = str(body)
+        assert "always_comb" in result
+        assert "begin" in result
+        assert "assign1 = value1;" in result
+        assert "assign2 = value2;" in result
+        assert "end" in result
+
+    def test_empty_combinational_block(self) -> None:
+        """Test empty combinational block."""
+        body = CombinationalBody()
+        result = str(body)
+        assert "always_comb" in result
+        assert "begin" in result
+        assert "end" in result
+
+    def test_combinational_with_if_statement(self) -> None:
+        """Test combinational block with if statement."""
+        cb = CombinationalBody()
+        ifb = IfBody()
+        with ifb.cm("condition") as b:
+            b += "assignment = value;"
+        cb += ifb
+
+        result = str(cb)
+        assert "always_comb" in result
+        assert "if (condition)" in result
+        assert "assignment = value;" in result