Update ruby codegen to cleanup build folder.

Summary:
This Diff cleans up the codegen folder for iOS when we install the pods. This is useful to start from a clean situation. The codegen runs after this step and we make sure that the file system is clean

## Changelog
[iOS][Changed] - Cleanup codegen build folder before installing the pods

Differential Revision: D38657027

fbshipit-source-id: aa9c4c7c6430c0a29aaa6cead82867f36990ad2e

scripts/cocoapods/__tests__/codegen_utils-test.rb

@@ -13,6 +13,7 @@
 require_relative "./test_utils/FinderMock.rb"
 require_relative "./test_utils/CodegenUtilsMock.rb"
 require_relative "./test_utils/CodegenScriptPhaseExtractorMock.rb"
+require_relative "./test_utils/FileUtilsMock.rb"
 
 class CodegenUtilsTests < Test::Unit::TestCase
     :base_path
@@ -29,6 +30,7 @@ def setup
     end
 
     def teardown
+        FileUtils::FileUtilsStorage.reset()
         Finder.reset()
         Pathname.reset()
         Pod::UI.reset()
@@ -368,6 +370,62 @@ def testUseReactCodegenDiscovery_whenParametersAreGood_executeCodegen
         ])
     end
 
+    # ============================= #
+    # Test - CleanUpCodegenFolder #
+    # ============================= #
+
+    def testCleanUpCodegenFolder_whenCleanupDone_doNothing
+        # Arrange
+        CodegenUtils.set_cleanup_done(true)
+        codegen_dir = "build/generated/ios"
+
+        # Act
+        CodegenUtils.clean_up_build_folder(@base_path, codegen_dir)
+
+        # Assert
+        assert_equal(FileUtils::FileUtilsStorage.rmrf_invocation_count, 0)
+        assert_equal(FileUtils::FileUtilsStorage.rmrf_paths, [])
+    end
+
+    def testCleanUpCodegenFolder_whenFolderDoesNotExists_doNothing
+        # Arrange
+        CodegenUtils.set_cleanup_done(false)
+        codegen_dir = "build/generated/ios"
+
+        # Act
+        CodegenUtils.clean_up_build_folder(@base_path, codegen_dir)
+
+        # Assert
+        assert_equal(FileUtils::FileUtilsStorage.rmrf_invocation_count, 0)
+        assert_equal(FileUtils::FileUtilsStorage.rmrf_paths, [])
+        assert_equal(Dir.glob_invocation, [])
+    end
+
+    def testCleanUpCodegenFolder_whenFolderExists_deleteItAndSetCleanupDone
+        # Arrange
+        CodegenUtils.set_cleanup_done(false)
+        codegen_dir = "build/generated/ios"
+        codegen_path = "#{@base_path}/#{codegen_dir}"
+        globs = [
+            "/MyModuleSpecs/MyModule.h",
+            "#{codegen_path}/MyModuleSpecs/MyModule.mm",
+            "#{codegen_path}/react/components/MyComponent/ShadowNode.h",
+            "#{codegen_path}/react/components/MyComponent/ShadowNode.mm",
+        ]
+        Dir.mocked_existing_dirs(codegen_path)
+        Dir.mocked_existing_globs(globs, "#{codegen_path}/*")
+
+        # Act
+        CodegenUtils.clean_up_build_folder(@base_path, codegen_dir)
+
+        # Assert
+        assert_equal(Dir.exist_invocation_params, [codegen_path])
+        assert_equal(Dir.glob_invocation, ["#{codegen_path}/*"])
+        assert_equal(FileUtils::FileUtilsStorage.rmrf_invocation_count, 1)
+        assert_equal(FileUtils::FileUtilsStorage.rmrf_paths, [globs])
+
+    end
+
     private
 
     def get_podspec_no_fabric_no_script

scripts/cocoapods/__tests__/test_utils/FileUtilsMock.rb

@@ -0,0 +1,39 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+#
+# This source code is licensed under the MIT license found in the
+# LICENSE file in the root directory of this source tree.
+
+module FileUtils
+
+
+    class FileUtilsStorage
+        @@RMRF_INVOCATION_COUNT = 0
+        @@RMRF_PATHS = []
+
+        def self.rmrf_invocation_count
+            return @@RMRF_INVOCATION_COUNT
+        end
+
+        def self.increase_rmrfi_invocation_count
+            @@RMRF_INVOCATION_COUNT += 1
+        end
+
+        def self.rmrf_paths
+            return @@RMRF_PATHS
+        end
+
+        def self.push_rmrf_path(path)
+            @@RMRF_PATHS.push(path)
+        end
+
+        def self.reset
+            @@RMRF_INVOCATION_COUNT = 0
+            @@RMRF_PATHS = []
+        end
+    end
+
+    def self.rm_rf(path)
+        FileUtilsStorage.push_rmrf_path(path)
+        FileUtilsStorage.increase_rmrfi_invocation_count
+    end
+end

scripts/cocoapods/codegen.rb

@@ -79,6 +79,7 @@ def run_codegen!(
   folly_version: '2021.07.22.00',
   codegen_utils: CodegenUtils.new()
   )
+
   if new_arch_enabled
     codegen_utils.use_react_native_codegen_discovery!(
       disable_codegen,

scripts/cocoapods/codegen_utils.rb

@@ -280,4 +280,24 @@ def use_react_native_codegen_discovery!(
 
       CodegenUtils.set_react_codegen_discovery_done(true)
     end
+
+    @@CLEANUP_DONE = false
+
+    def self.set_cleanup_done(newValue)
+      @@CLEANUP_DONE = newValue
+    end
+
+    def self.cleanup_done
+      return @@CLEANUP_DONE
+    end
+
+    def self.clean_up_build_folder(app_path, codegen_dir)
+      return if CodegenUtils.cleanup_done()
+
+      codegen_path = File.join(app_path, codegen_dir)
+      return if !Dir.exist?(codegen_path)
+
+      FileUtils.rm_rf(Dir.glob("#{codegen_path}/*"))
+      CodegenUtils.set_cleanup_done(true)
+    end
 end

scripts/react_native_pods.rb

@@ -43,6 +43,8 @@ def use_react_native! (
   app_path: '..',
   config_file_dir: '')
 
+  CodegenUtils.clean_up_build_folder(app_path, $CODEGEN_OUTPUT_DIR)
+
   prefix = path
 
   # The version of folly that must be used