Merge pull request rails#55205 from zzak/re-53174

Ensure yarn and bun version fallback

Author: byroot

railties/lib/rails/generators/app_base.rb

@@ -529,31 +529,30 @@ def using_bun?
         using_js_runtime? && %w[bun].include?(options[:javascript])
       end
 
+      def capture_command(command, pattern)
+        `#{command}`[pattern]
+      rescue SystemCallError
+        nil
+      end
+
       def node_version
         if using_node?
           ENV.fetch("NODE_VERSION") do
-            `node --version`[/\d+\.\d+\.\d+/]
-          rescue
-            NODE_LTS_VERSION
+            capture_command("node --version", /\d+\.\d+\.\d+/) || NODE_LTS_VERSION
           end
         end
       end
 
       def dockerfile_yarn_version
-        using_node? and `yarn --version`[/\d+\.\d+\.\d+/]
-      rescue
-        "latest"
+        capture_command("yarn --version", /\d+\.\d+\.\d+/) || "latest"
       end
 
       def yarn_through_corepack?
-        true if dockerfile_yarn_version == "latest"
-        dockerfile_yarn_version >= "2"
+        using_node? and "#{dockerfile_yarn_version}" >= "2"
       end
 
       def dockerfile_bun_version
-        using_bun? and `bun --version`[/\d+\.\d+\.\d+/]
-      rescue
-        BUN_VERSION
+        capture_command("bun --version", /\d+\.\d+\.\d+/) || BUN_VERSION
       end
 
       def dockerfile_binfile_fixups

railties/test/generators/app_generator_test.rb

@@ -925,6 +925,22 @@ def test_esbuild_option_with_js_argument
     assert_gem "jsbundling-rails"
   end
 
+  def test_esbuild_without_yarn_installed
+    generator([destination_root], javascript: "esbuild")
+
+    # fallback to latest when yarn is not installed
+    generator.stub :dockerfile_yarn_version, "latest" do
+      quietly { generator.invoke_all }
+    end
+
+    assert_gem "jsbundling-rails"
+    assert_file "Dockerfile" do |content|
+      assert_match(/ARG YARN_VERSION=latest/, content)
+
+      assert_match("RUN corepack enable && yarn set version $YARN_VERSION", content)
+    end
+  end
+
   def test_bun_option
     generator([destination_root], javascript: "bun")
 
@@ -949,6 +965,23 @@ def test_bun_option_with_js_argument
     assert_gem "jsbundling-rails"
   end
 
+  def test_bun_without_bun_installed
+    generator([destination_root], javascript: "bun")
+    bun_version = generator.class.const_get(:BUN_VERSION)
+
+    # fallback to constant when bun is not installed
+    generator.stub :dockerfile_bun_version, bun_version do
+      quietly { generator.invoke_all }
+    end
+
+    assert_gem "jsbundling-rails"
+    assert_file "Dockerfile" do |content|
+      assert_match(/ARG BUN_VERSION=#{bun_version}/, content)
+
+      assert_match("RUN bun install --frozen-lockfile", content)
+    end
+  end
+
   def test_skip_javascript_option_with_skip_javascript_argument
     run_generator [destination_root, "--skip-javascript"]
     assert_no_gem "stimulus-rails"