Fix build_codegen! not finding @react-native/codegen in pnpm setups (#41456)

`build_codegen!` currently assumes that `@react-native/codegen` gets
installed next to `react-native`. In a pnpm setup, it's found under
`/~/react-native/node_modules/@react-native/codegen` instead.

However, as @dmytrorykun pointed out, we don't actually need to build
it outside of this repository.

Author: tido64

packages/react-native/scripts/cocoapods/__tests__/codegen-test.rb

@@ -68,32 +68,32 @@ def testCheckAndGenerateEmptyThirdPartyProvider_whenFileAlreadyExists_doNothing(
         assert_equal(Pod::Executable.executed_commands.length, 0)
     end
 
-    def testCheckAndGenerateEmptyThirdPartyProvider_whenHeaderMissingAndCodegenMissing_raiseError()
+    def testCheckAndGenerateEmptyThirdPartyProvider_whenHeaderMissingAndCodegenMissing_dontBuildCodegen()
 
         # Arrange
         FileMock.mocked_existing_files([
             @base_path + "/build/" + @third_party_provider_implementation,
         ])
 
         # Act
-        assert_raise {
+        assert_nothing_raised {
             checkAndGenerateEmptyThirdPartyProvider!(@prefix, false, dir_manager: DirMock, file_manager: FileMock)
         }
 
         # Assert
         assert_equal(Pathname.pwd_invocation_count, 1)
         assert_equal(Pod::Config.instance.installation_root.relative_path_from_invocation_count, 1)
         assert_equal(FileMock.exist_invocation_params, [
-            @prefix + "/React/Fabric/" + @third_party_provider_header
+            @prefix + "/React/Fabric/" + @third_party_provider_header,
+            @prefix + "/React/Fabric/tmpSchemaList.txt",
         ])
         assert_equal(DirMock.exist_invocation_params, [
             @base_path + "/"+ @prefix + "/../react-native-codegen",
-            @base_path + "/"+ @prefix + "/../@react-native/codegen",
         ])
-        assert_equal(Pod::UI.collected_messages, [])
+        assert_equal(Pod::UI.collected_messages, ["[Codegen] generating an empty RCTThirdPartyFabricComponentsProvider"])
         assert_equal($collected_commands, [])
-        assert_equal(FileMock.open_files.length, 0)
-        assert_equal(Pod::Executable.executed_commands.length, 0)
+        assert_equal(FileMock.open_files.length, 1)
+        assert_equal(Pod::Executable.executed_commands.length, 1)
     end
 
     def testCheckAndGenerateEmptyThirdPartyProvider_whenImplementationMissingAndCodegenrepoExists_dontBuildCodegen()
@@ -145,7 +145,7 @@ def testCheckAndGenerateEmptyThirdPartyProvider_whenImplementationMissingAndCode
 
     def testCheckAndGenerateEmptyThirdPartyProvider_whenBothMissing_buildCodegen()
         # Arrange
-        codegen_cli_path = @base_path + "/" + @prefix + "/../@react-native/codegen"
+        codegen_cli_path = @base_path + "/" + @prefix + "/../react-native-codegen"
         DirMock.mocked_existing_dirs([
             codegen_cli_path,
         ])
@@ -160,15 +160,14 @@ def testCheckAndGenerateEmptyThirdPartyProvider_whenBothMissing_buildCodegen()
             @prefix + "/React/Fabric/" + @tmp_schema_list_file
         ])
         assert_equal(DirMock.exist_invocation_params, [
-            @base_path + "/" + @prefix + "/../react-native-codegen",
             codegen_cli_path,
             codegen_cli_path + "/lib",
         ])
         assert_equal(Pod::UI.collected_messages, [
-            "[Codegen] building #{codegen_cli_path}.",
+            "[Codegen] building #{codegen_cli_path}",
             "[Codegen] generating an empty RCTThirdPartyFabricComponentsProvider"
         ])
-        assert_equal($collected_commands, ["~/app/ios/../../../@react-native/codegen/scripts/oss/build.sh"])
+        assert_equal($collected_commands, ["~/app/ios/../../../react-native-codegen/scripts/oss/build.sh"])
         assert_equal(FileMock.open_files[0].collected_write, ["[]"])
         assert_equal(FileMock.open_files[0].fsync_invocation_count, 1)
         assert_equal(Pod::Executable.executed_commands[0], {

packages/react-native/scripts/cocoapods/codegen.rb

@@ -11,23 +11,12 @@
 # - dir_manager: a class that implements the `Dir` interface. Defaults to `Dir`, the Dependency can be injected for testing purposes.
 # @throws an error if it could not find the codegen folder.
 def build_codegen!(react_native_path, relative_installation_root, dir_manager: Dir)
-    codegen_repo_path = "#{relative_installation_root}/#{react_native_path}/../react-native-codegen";
-    codegen_npm_path = "#{relative_installation_root}/#{react_native_path}/../@react-native/codegen";
-    codegen_cli_path = ""
+  codegen_repo_path = "#{relative_installation_root}/#{react_native_path}/../react-native-codegen";
+  return unless dir_manager.exist?(codegen_repo_path) && !dir_manager.exist?("#{codegen_repo_path}/lib")
 
-    if dir_manager.exist?(codegen_repo_path)
-      codegen_cli_path = codegen_repo_path
-    elsif dir_manager.exist?(codegen_npm_path)
-      codegen_cli_path = codegen_npm_path
-    else
-      raise "[codegen] Could not find react-native-codegen."
-    end
-
-    if !dir_manager.exist?("#{codegen_cli_path}/lib")
-      Pod::UI.puts "[Codegen] building #{codegen_cli_path}."
-      system("#{codegen_cli_path}/scripts/oss/build.sh")
-    end
-  end
+  Pod::UI.puts "[Codegen] building #{codegen_repo_path}"
+  system("#{codegen_repo_path}/scripts/oss/build.sh")
+end
 
 # It generates an empty `ThirdPartyProvider`, required by Fabric to load the components
 #