Added test to ensure extension rules pin the right rules_rust version

extensions/bindgen/BUILD.bazel

@@ -10,6 +10,7 @@ package(default_visibility = ["//visibility:public"])
 
 exports_files([
     "defs.bzl",
+    "MODULE.bazel",
 ])
 
 toolchain_type(

extensions/bindgen/MODULE.bazel

@@ -7,7 +7,7 @@ module(
 
 bazel_dep(
     name = "rules_rust",
-    version = "0.54.1",
+    version = "0.55.0",
 )
 local_path_override(
     module_name = "rules_rust",

extensions/bindgen/test/bzlmod/BUILD.bazel

@@ -0,0 +1,6 @@
+load("@rules_rust//test/bzl_version:bzl_ext_version_test.bzl", "bzl_ext_version_test")
+
+bzl_ext_version_test(
+    name = "bzl_ext_version_test",
+    module_bazel = "//:MODULE.bazel",
+)

extensions/prost/BUILD.bazel

@@ -4,6 +4,7 @@ package(default_visibility = ["//visibility:public"])
 
 exports_files([
     "defs.bzl",
+    "MODULE.bazel",
 ])
 
 toolchain_type(

extensions/prost/MODULE.bazel

@@ -7,7 +7,7 @@ module(
 
 bazel_dep(
     name = "rules_rust",
-    version = "0.54.1",
+    version = "0.55.0",
 )
 local_path_override(
     module_name = "rules_rust",

extensions/prost/private/tests/bzlmod/BUILD.bazel

@@ -0,0 +1,6 @@
+load("@rules_rust//test/bzl_version:bzl_ext_version_test.bzl", "bzl_ext_version_test")
+
+bzl_ext_version_test(
+    name = "bzl_ext_version_test",
+    module_bazel = "//:MODULE.bazel",
+)

extensions/protobuf/BUILD.bazel

@@ -11,6 +11,7 @@ toolchain_type(
 
 exports_files([
     "defs.bzl",
+    "MODULE.bazel",
 ])
 
 rust_binary(

extensions/protobuf/MODULE.bazel

@@ -7,7 +7,7 @@ module(
 
 bazel_dep(
     name = "rules_rust",
-    version = "0.54.1",
+    version = "0.55.0",
 )
 local_path_override(
     module_name = "rules_rust",

extensions/protobuf/test/bzlmod/BUILD.bazel

@@ -0,0 +1,6 @@
+load("@rules_rust//test/bzl_version:bzl_ext_version_test.bzl", "bzl_ext_version_test")
+
+bzl_ext_version_test(
+    name = "bzl_ext_version_test",
+    module_bazel = "//:MODULE.bazel",
+)

extensions/wasm_bindgen/BUILD.bazel

@@ -5,6 +5,7 @@ package(default_visibility = ["//visibility:public"])
 
 exports_files([
     "defs.bzl",
+    "MODULE.bazel",
 ])
 
 toolchain_type(

extensions/wasm_bindgen/MODULE.bazel

@@ -7,7 +7,7 @@ module(
 
 bazel_dep(
     name = "rules_rust",
-    version = "0.54.1",
+    version = "0.55.0",
 )
 local_path_override(
     module_name = "rules_rust",

extensions/wasm_bindgen/test/bzlmod/BUILD.bazel

@@ -0,0 +1,6 @@
+load("@rules_rust//test/bzl_version:bzl_ext_version_test.bzl", "bzl_ext_version_test")
+
+bzl_ext_version_test(
+    name = "bzl_ext_version_test",
+    module_bazel = "//:MODULE.bazel",
+)

test/bzl_version/BUILD.bazel

@@ -2,6 +2,7 @@ load(":bzl_version_test.bzl", "bzl_version_test")
 
 exports_files([
     "bzl_version_test.rs",
+    "bzl_ext_version_test.rs",
 ])
 
 bzl_version_test(

test/bzl_version/bzl_ext_version_test.bzl

@@ -0,0 +1,30 @@
+"""Test utiltiies for ensuring bzlmod and workspace versions match"""
+
+load("//rust:defs.bzl", "rust_test")
+
+def bzl_ext_version_test(name, module_bazel, **kwargs):
+    """A test for ensuring a rules_rust extension bzlmod repo is in sync with the core rules_rust version.
+
+    Args:
+        name (str): The name of the test
+        module_bazel (label): The label of a `MODULE.bazel` file.
+        **kwargs (dict): Additional keyword arguments.
+    """
+
+    rust_test(
+        name = name,
+        srcs = [Label("//test/bzl_version:bzl_ext_version_test.rs")],
+        data = [
+            module_bazel,
+            Label("@rules_rust//:MODULE.bazel"),
+        ],
+        edition = "2021",
+        env = {
+            "CORE_MODULE_BAZEL": "$(rlocationpath @rules_rust//:MODULE.bazel)",
+            "MODULE_BAZEL": "$(rlocationpath {})".format(module_bazel),
+        },
+        deps = [
+            Label("//tools/runfiles"),
+        ],
+        **kwargs
+    )

test/bzl_version/bzl_ext_version_test.rs

@@ -0,0 +1,79 @@
+//! A test to ensure the rules_rust extension bzlmod core version is accurate.
+
+use runfiles::Runfiles;
+
+fn parse_rules_rust_version(text: &str) -> String {
+    let mut in_module = false;
+    let mut found_dep = false;
+    for line in text.split('\n') {
+        if in_module {
+            if line.ends_with(')') {
+                in_module = false;
+                continue;
+            }
+
+            if found_dep {
+                if let Some((param, value)) = line.rsplit_once(" = ") {
+                    if param.trim() == "version" {
+                        return value.trim().trim_matches(',').trim_matches('"').to_owned();
+                    }
+                }
+            }
+
+            if line.trim().starts_with("name = \"rules_rust\"") {
+                found_dep = true;
+                continue;
+            }
+
+            continue;
+        }
+
+        if line.starts_with("bazel_dep(") {
+            assert!(!found_dep, "Found `rules_rust` dep but couldn't determine version.");
+            in_module = true;
+            continue;
+        }
+    }
+    panic!("Failed to find rules_rust version in:\n```\n{}\n```", text);
+}
+
+fn parse_module_bazel_version(text: &str) -> String {
+    let mut found_module = false;
+    for line in text.split('\n') {
+        if found_module {
+            assert!(!line.ends_with(')'), "Failed to parse version");
+            if let Some((param, value)) = line.rsplit_once(" = ") {
+                if param.trim() == "version" {
+                    return value.trim().trim_matches(',').trim_matches('"').to_owned();
+                }
+            }
+        } else if line.starts_with("module(") {
+            found_module = true;
+            continue;
+        }
+    }
+    panic!("Failed to find MODULE.bazel version");
+}
+
+/// If this test fails it means `//:version.bzl` and `//:MODULE.bazel` need to
+/// be synced up. `//:version.bzl` should contain the source of truth.
+#[test]
+fn module_bzl_has_correct_version() {
+    let r = Runfiles::create().unwrap();
+
+    let core_version = {
+        let path = runfiles::rlocation!(r, std::env::var("CORE_MODULE_BAZEL").unwrap()).unwrap();
+        let text = std::fs::read_to_string(path).unwrap();
+        parse_module_bazel_version(&text)
+    };
+    let requested_version = {
+        let path = runfiles::rlocation!(r, std::env::var("MODULE_BAZEL").unwrap()).unwrap();
+        let text = std::fs::read_to_string(path).unwrap();
+        parse_rules_rust_version(&text)
+    };
+
+    assert_eq!(
+        core_version, requested_version,
+        "Core rules_rust and the dependency for the current module are out of sync."
+    );
+}