Make import! of protobuf_gtest_matchers work properly.

This required making a shim file for a crate to be able to re-export either the _cpp or _upb impl so that it can be one crate that conditionally delegates to the intended one.

PiperOrigin-RevId: 688639897

rust/BUILD

@@ -161,21 +161,25 @@ rust_library(
     deps = [":protobuf_cpp"],
 )
 
-alias(
+rust_library(
     name = "protobuf_gtest_matchers",
-    actual = select({
-        ":use_upb_kernel": ":protobuf_gtest_matchers_upb",
-        "//conditions:default": ":protobuf_gtest_matchers_cpp",
+    testonly = True,
+    srcs = ["gtest_matchers.rs"],
+    aliases = select({
+        ":use_upb_kernel": {"//rust:protobuf_gtest_matchers_upb": "protobuf_gtest_matchers_impl"},
+        "//conditions:default": {"//rust:protobuf_gtest_matchers_cpp": "protobuf_gtest_matchers_impl"},
+    }),
+    visibility = ["//visibility:public"],
+    deps = select({
+        ":use_upb_kernel": [":protobuf_gtest_matchers_upb"],
+        "//conditions:default": [":protobuf_gtest_matchers_cpp"],
     }),
-    visibility = [
-        "//visibility:public",
-    ],
 )
 
 rust_library(
     name = "protobuf_gtest_matchers_cpp",
     testonly = True,
-    srcs = ["gtest_matchers.rs"],
+    srcs = ["gtest_matchers_impl.rs"],
     aliases = {
         "//rust:protobuf_cpp": "protobuf",
     },
@@ -189,7 +193,7 @@ rust_library(
 rust_library(
     name = "protobuf_gtest_matchers_upb",
     testonly = True,
-    srcs = ["gtest_matchers.rs"],
+    srcs = ["gtest_matchers_impl.rs"],
     aliases = {
         "//rust:protobuf_upb": "protobuf",
     },

rust/gtest_matchers.rs

@@ -5,31 +5,7 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
-use googletest::description::Description;
-use googletest::matcher::{Matcher, MatcherBase, MatcherResult};
-use protobuf::__internal::MatcherEq;
+extern crate protobuf_gtest_matchers_impl;
 
-#[derive(MatcherBase)]
-pub struct MessageMatcher<T: MatcherEq> {
-    expected: T,
-}
-
-impl<T> Matcher<&T> for MessageMatcher<T>
-where
-    T: MatcherEq,
-{
-    fn matches(&self, actual: &T) -> MatcherResult {
-        actual.matches(&self.expected).into()
-    }
-
-    fn describe(&self, matcher_result: MatcherResult) -> Description {
-        match matcher_result {
-            MatcherResult::Match => format!("is equal to {:?}", self.expected).into(),
-            MatcherResult::NoMatch => format!("is not equal to {:?}", self.expected).into(),
-        }
-    }
-}
-
-pub fn proto_eq<T: MatcherEq>(expected: T) -> MessageMatcher<T> {
-    MessageMatcher { expected }
-}
+// Re-export all symbols from the underlying implementation of gtest_matchers.
+pub use protobuf_gtest_matchers_impl::*;

rust/gtest_matchers_impl.rs

@@ -0,0 +1,35 @@
+// Protocol Buffers - Google's data interchange format
+// Copyright 2024 Google LLC.  All rights reserved.
+//
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file or at
+// https://developers.google.com/open-source/licenses/bsd
+
+use googletest::description::Description;
+use googletest::matcher::{Matcher, MatcherBase, MatcherResult};
+use protobuf::__internal::MatcherEq;
+
+#[derive(MatcherBase)]
+pub struct MessageMatcher<T: MatcherEq> {
+    expected: T,
+}
+
+impl<T> Matcher<&T> for MessageMatcher<T>
+where
+    T: MatcherEq,
+{
+    fn matches(&self, actual: &T) -> MatcherResult {
+        actual.matches(&self.expected).into()
+    }
+
+    fn describe(&self, matcher_result: MatcherResult) -> Description {
+        match matcher_result {
+            MatcherResult::Match => format!("is equal to {:?}", self.expected).into(),
+            MatcherResult::NoMatch => format!("is not equal to {:?}", self.expected).into(),
+        }
+    }
+}
+
+pub fn proto_eq<T: MatcherEq>(expected: T) -> MessageMatcher<T> {
+    MessageMatcher { expected }
+}

rust/test/shared/gtest_matchers_test.rs

@@ -5,6 +5,10 @@
 // license that can be found in the LICENSE file or at
 // https://developers.google.com/open-source/licenses/bsd
 
+google3::import! {
+  "//third_party/protobuf/rust:protobuf_gtest_matchers";
+}
+
 use edition_unittest_rust_proto::TestAllTypes as TestAllTypesEditions;
 use googletest::prelude::*;
 use paste::paste;