Improve resolving PYTHONPATH in cocotb_test rule

This PR adds all imports from the deps section to the PYTHONPATH
to ensure that all transitive dependencies are resolved correctly.

Internal-tag: [#46586]
Signed-off-by: Robert Winkler <[email protected]>

Author: rw1nkler

cocotb/cocotb.bzl

@@ -68,6 +68,36 @@ def _collect_verilog_files(ctx):
 def _collect_vhdl_files(ctx):
     return ctx.files.vhdl_sources
 
+def _collect_python_imports(ctx):
+    collected_imports = []
+    for dep in ctx.attr.deps:
+        if PyInfo in dep:
+            root = dep.label.workspace_root
+            name = dep.label.workspace_name
+            prefix = root.removesuffix(name)
+            imports = dep[PyInfo].imports.to_list()
+            collected_imports += [(prefix, imports)]
+
+    return collected_imports
+
+def _get_import_paths_for_python_deps(ctx):
+    collected_paths = _collect_python_imports(ctx)
+
+    import_paths = []
+    for prefix, paths in collected_paths:
+        for path in paths:
+            import_paths += [prefix + path]
+
+    return _remove_duplicates_from_list(import_paths)
+
+def _get_test_module_paths(ctx):
+    module_paths = [module.dirname for module in ctx.files.test_module]
+    return _remove_duplicates_from_list(module_paths)
+
+def _get_pythonpath_for_exec(ctx):
+    paths = _get_test_module_paths(ctx) + _get_import_paths_for_python_deps(ctx)
+    return ":".join([str(p) for p in paths])
+
 def _cocotb_test_impl(ctx):
     # prepare arguments for the test command
     vhdl_files = _collect_vhdl_files(ctx)
@@ -145,9 +175,7 @@ def _cocotb_test_impl(ctx):
     )
 
     # specify pythonpath for the script
-    test_module_paths = _remove_duplicates_from_list([module.dirname for module in ctx.files.test_module])
-    pypath = ":".join([str(p) for p in test_module_paths])
-    env = {"PYTHONPATH": pypath}
+    env = {"PYTHONPATH": _get_pythonpath_for_exec(ctx)}
 
     # return the information about testing script and its dependencies
     return [