Add .bzl files explicitly to toolchain tests to detect .bzl file changes (#815)

Co-authored-by: Thulio Ferraz Assis <3149049+f0rmiga@users.noreply.github.com>

BUILD

diff --git a/BUILD b/BUILD
index ebdf74e..7ea2aa4 100644
--- a/BUILD
+++ b/BUILD
@@ -39,6 +39,7 @@
     ],
     visibility = [
         "//examples:__pkg__",
+        "//python/tests/toolchains:__pkg__",
         "//tests:__pkg__",
     ],
 )

python/tests/toolchains/defs.bzl

diff --git a/python/tests/toolchains/defs.bzl b/python/tests/toolchains/defs.bzl
index 8c07d23..2abc1ed 100644
--- a/python/tests/toolchains/defs.bzl
+++ b/python/tests/toolchains/defs.bzl
@@ -39,10 +39,6 @@
     )
 
     python_version_test = ctx.actions.declare_file("/".join([ctx.attr.python_version, "python_version_test.py"]))
-
-    # With the current approach in the run_acceptance_test.sh, we use this
-    # symlink to find the absolute path to the rules_python to be passed to the
-    # --override_repository rules_python=<rules_python_path>.
     ctx.actions.symlink(
         target_file = ctx.file._python_version_test,
         output = python_version_test,
@@ -92,7 +88,7 @@
         python_version_test,
         run_acceptance_test_py,
         workspace,
-    ]
+    ] + ctx.files._distribution
     return [DefaultInfo(
         executable = executable,
         files = depset(
@@ -126,6 +122,10 @@
             allow_single_file = True,
             default = Label("//python/tests/toolchains/workspace_template:BUILD.bazel.tmpl"),
         ),
+        "_distribution": attr.label(
+            doc = "The rules_python source distribution.",
+            default = Label("//:distribution"),
+        ),
         "_python_version_test": attr.label(
             doc = "The python_version_test.py used to test the Python version.",
             allow_single_file = True,

python/tests/toolchains/run_acceptance_test.py.tmpl

diff --git a/python/tests/toolchains/run_acceptance_test.py.tmpl b/python/tests/toolchains/run_acceptance_test.py.tmpl
index 51eba3d..b3071a7 100644
--- a/python/tests/toolchains/run_acceptance_test.py.tmpl
+++ b/python/tests/toolchains/run_acceptance_test.py.tmpl
@@ -21,12 +21,7 @@
     @classmethod
     def setUpClass(cls):
         os.chdir("%test_location%")
-        python_version_test_dirname = os.path.dirname(
-            os.path.realpath("python_version_test.py")
-        )
-        rules_python_path = os.path.normpath(
-            os.path.join(python_version_test_dirname, "..", "..", "..", "..")
-        )
+        rules_python_path = os.path.join(os.environ["TEST_SRCDIR"], "rules_python")
 
         if %is_windows%:
             test_tmpdir = os.environ["TEST_TMPDIR"]