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

* initial refactor

* fix cocotb tests

* fix typecheck

* install verilator

tests/unroll/conftest.py

@@ -0,0 +1,40 @@
+from collections.abc import Callable
+
+import pytest
+from systemrdl.node import AddrmapNode
+
+
+@pytest.fixture
+def sample_rdl(compile_rdl: Callable[..., AddrmapNode]) -> AddrmapNode:
+    """Create a simple RDL design with an array."""
+    rdl_source = """
+    addrmap top {
+        reg my_reg {
+            field {
+                sw=rw;
+                hw=r;
+            } data[31:0];
+        };
+        
+        my_reg regs[4] @ 0x0 += 0x4;
+    };
+    """
+    return compile_rdl(rdl_source)
+
+
+@pytest.fixture
+def multidim_array_rdl(compile_rdl: Callable[..., AddrmapNode]) -> AddrmapNode:
+    """Create an RDL design with a multi-dimensional array."""
+    rdl_source = """
+    addrmap top {
+        reg my_reg {
+            field {
+                sw=rw;
+                hw=r;
+            } data[31:0];
+        };
+        
+        my_reg matrix[2][3] @ 0x0 += 0x4;
+    };
+    """
+    return compile_rdl(rdl_source)