Add repository_utils_test.bzl (#846)

* Add repository_utils_test.bzl

* Add produce_tool_path tests

* Buildifier

test/unit/repository_utils/BUILD.bazel

@@ -0,0 +1,4 @@
+load(":repository_utils_test.bzl", "repository_utils_test_suite")
+
+############################ UNIT TESTS #############################
+repository_utils_test_suite(name = "repository_utils_test_suite")

test/unit/repository_utils/repository_utils_test.bzl

@@ -0,0 +1,52 @@
+"""Unit tests for repository_utils.bzl."""
+
+load("@bazel_skylib//lib:unittest.bzl", "asserts", "unittest")
+
+# buildifier: disable=bzl-visibility
+load("//rust/private:repository_utils.bzl", "produce_tool_path", "produce_tool_suburl")
+
+def _produce_tool_suburl_test_impl(ctx):
+    env = unittest.begin(ctx)
+    asserts.equals(
+        env,
+        "2020-05-22/rust-std-nightly-x86_64-unknown-linux-gnu",
+        produce_tool_suburl(
+            iso_date = "2020-05-22",
+            tool_name = "rust-std",
+            version = "nightly",
+            target_triple = "x86_64-unknown-linux-gnu",
+        ),
+    )
+    asserts.equals(
+        env,
+        "rust-std-nightly-x86_64-unknown-linux-gnu",
+        produce_tool_suburl(
+            tool_name = "rust-std",
+            version = "nightly",
+            target_triple = "x86_64-unknown-linux-gnu",
+        ),
+    )
+    return unittest.end(env)
+
+def _produce_tool_path_test_impl(ctx):
+    env = unittest.begin(ctx)
+    asserts.equals(
+        env,
+        "rust-std-nightly-x86_64-unknown-linux-gnu",
+        produce_tool_path(
+            tool_name = "rust-std",
+            version = "nightly",
+            target_triple = "x86_64-unknown-linux-gnu",
+        ),
+    )
+    return unittest.end(env)
+
+produce_tool_suburl_test = unittest.make(_produce_tool_suburl_test_impl)
+produce_tool_path_test = unittest.make(_produce_tool_path_test_impl)
+
+def repository_utils_test_suite(name):
+    unittest.suite(
+        name,
+        produce_tool_suburl_test,
+        produce_tool_path_test,
+    )