Remove genfiles_dir retrieval method (#203)

genfiles_dir has been the same as bin_dir for several Bazel releases, and is
being fully removed in upcoming Bazel release.
diff --git a/lib/unittest.bzl b/lib/unittest.bzl
index 718eca4..4506c11 100644
--- a/lib/unittest.bzl
+++ b/lib/unittest.bzl
@@ -126,14 +126,13 @@
         toolchains = [TOOLCHAIN_TYPE],
     )
 
-_ActionInfo = provider(fields = ["actions", "bin_path", "genfiles_path"])
+_ActionInfo = provider(fields = ["actions", "bin_path"])
 
 def _action_retrieving_aspect_impl(target, ctx):
     return [
         _ActionInfo(
             actions = target.actions,
             bin_path = ctx.bin_dir.path,
-            genfiles_path = ctx.genfiles_dir.path,
         ),
     ]
 
@@ -481,17 +480,6 @@
     """
     return _target_under_test(env)[_ActionInfo].bin_path
 
-def _target_genfiles_dir_path(env):
-    """Returns ctx.genfiles_dir.path for the target under test.
-
-    Args:
-      env: The test environment returned by `analysistest.begin`.
-
-    Returns:
-      Output genfiles dir path string.
-    """
-    return _target_under_test(env)[_ActionInfo].genfiles_path
-
 def _target_under_test(env):
     """Returns the target under test.
 
@@ -533,6 +521,5 @@
     fail = _fail,
     target_actions = _target_actions,
     target_bin_dir_path = _target_bin_dir_path,
-    target_genfiles_dir_path = _target_genfiles_dir_path,
     target_under_test = _target_under_test,
 )
diff --git a/tests/unittest_tests.bzl b/tests/unittest_tests.bzl
index e3ca45b..ed1c599 100644
--- a/tests/unittest_tests.bzl
+++ b/tests/unittest_tests.bzl
@@ -180,44 +180,31 @@
 ########################################
 ####### inspect_output_dirs_test #######
 ########################################
-_OutputDirInfo = provider(fields = ["bin_path", "genfiles_path"])
+_OutputDirInfo = provider(fields = ["bin_path"])
 
 def _inspect_output_dirs_test(ctx):
     """Test verifying output directories used by a test."""
     env = analysistest.begin(ctx)
 
-    # Assert that the output dirs observed by the aspect added by analysistest
-    # are the same as those observed by the rule directly, even when that's
-    # under a config transition and therefore not the same as the output
-    # dirs used by the test rule.
+    # Assert that the output bin dir observed by the aspect added by analysistest
+    # is the same as those observed by the rule directly, even when that's
+    # under a config transition and therefore not the same as the bin dir
+    # used by the test rule.
     bin_path = analysistest.target_bin_dir_path(env)
-    genfiles_path = analysistest.target_genfiles_dir_path(env)
     target_under_test = analysistest.target_under_test(env)
     asserts.false(env, not bin_path, "bin dir path not found.")
-    asserts.false(env, not genfiles_path, "genfiles path not found.")
     asserts.false(
         env,
         bin_path == ctx.bin_dir.path,
         "bin dir path expected to differ between test and target_under_test.",
     )
-    asserts.false(
-        env,
-        genfiles_path == ctx.genfiles_dir.path,
-        "genfiles dir path expected to differ between test and target_under_test.",
-    )
     asserts.equals(env, bin_path, target_under_test[_OutputDirInfo].bin_path)
-    asserts.equals(
-        env,
-        genfiles_path,
-        target_under_test[_OutputDirInfo].genfiles_path,
-    )
     return analysistest.end(env)
 
 def _inspect_output_dirs_fake_rule(ctx):
     return [
         _OutputDirInfo(
             bin_path = ctx.bin_dir.path,
-            genfiles_path = ctx.genfiles_dir.path,
         ),
     ]