Improve Codegen Cleanup (#35642)

Summary:
This PR adds a safety check in case the Cocoapod build script is not able to clean the build folder.
We had evidences where this process failed, and in this way the user has a clear and actionable message to fix its situation.

## Changelog

[iOS][Added] - Add message with instructions about what to do if the cleanup of the build folder fails.

Pull Request resolved: #35642

Test Plan:
I was not able to reproduce the issue locally.
The fix is not destructive, let's see if the amount of issues decreases.

Reviewed By: dmytrorykun

Differential Revision: D42067939

Pulled By: cipolleschi

fbshipit-source-id: 433dbfaec42a1bf460dc9a48051aa51ec6e12d16

scripts/cocoapods/__tests__/codegen_utils-test.rb

@@ -423,12 +423,59 @@ def testCleanUpCodegenFolder_whenFolderExists_deleteItAndSetCleanupDone
         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(Dir.exist_invocation_params, [codegen_path, codegen_path])
+        assert_equal(Dir.glob_invocation, ["#{codegen_path}/*", "#{codegen_path}/*"])
         assert_equal(FileUtils::FileUtilsStorage.rmrf_invocation_count, 1)
         assert_equal(FileUtils::FileUtilsStorage.rmrf_paths, [globs])
         assert_equal(CodegenUtils.cleanup_done(), true)
+    end
+
+    # ===================================== #
+    # Test - Assert Codegen Folder Is Empty #
+    # ===================================== #
+
+    def test_assertCodegenFolderIsEmpty_whenItDoesNotExists_doesNotAbort
+        # Arrange
+        codegen_dir = "build/generated/ios"
+        codegen_path = "#{@base_path}/#{codegen_dir}"
+
+        # Act
+        CodegenUtils.assert_codegen_folder_is_empty(@base_path, codegen_dir)
+
+        # Assert
+        assert_equal(Pod::UI.collected_warns, [])
+    end
 
+    def test_assertCodegenFolderIsEmpty_whenItExistsAndIsEmpty_doesNotAbort
+        # Arrange
+        codegen_dir = "build/generated/ios"
+        codegen_path = "#{@base_path}/#{codegen_dir}"
+        Dir.mocked_existing_dirs(codegen_path)
+        Dir.mocked_existing_globs([], "#{codegen_path}/*")
+
+        # Act
+        CodegenUtils.assert_codegen_folder_is_empty(@base_path, codegen_dir)
+
+        # Assert
+        assert_equal(Pod::UI.collected_warns, [])
+    end
+
+    def test_assertCodegenFolderIsEmpty_whenItIsNotEmpty_itAborts
+        # Arrange
+        codegen_dir = "build/generated/ios"
+        codegen_path = "#{@base_path}/#{codegen_dir}"
+        Dir.mocked_existing_dirs(codegen_path)
+        Dir.mocked_existing_globs(["#{codegen_path}/MyModuleSpecs/MyModule.mm",], "#{codegen_path}/*")
+
+        # Act
+        assert_raises() {
+            CodegenUtils.assert_codegen_folder_is_empty(@base_path, codegen_dir)
+        }
+
+        # Assert
+        assert_equal(Pod::UI.collected_warns, [
+            "Unable to remove the content of ~/app/ios/build/generated/ios folder. Please run rm -rf ~/app/ios/build/generated/ios and try again."
+        ])
     end
 
     private

scripts/cocoapods/__tests__/test_utils/DirMock.rb

@@ -49,7 +49,11 @@ def self.glob_invocation
 
     def self.glob(path)
         @@glob_invocation.push(path)
-        return @@mocked_existing_globs[path]
+        return @@mocked_existing_globs[path] != nil ? @@mocked_existing_globs[path] : []
+    end
+
+    def self.remove_mocked_paths(path)
+        @@mocked_existing_globs = @@mocked_existing_globs.select { |k, v| v != path }
     end
 
     def self.set_pwd(pwd)

scripts/cocoapods/__tests__/test_utils/FileUtilsMock.rb

@@ -3,9 +3,9 @@
 # This source code is licensed under the MIT license found in the
 # LICENSE file in the root directory of this source tree.
 
-module FileUtils
-
+require_relative './DirMock.rb'
 
+module FileUtils
     class FileUtilsStorage
         @@RMRF_INVOCATION_COUNT = 0
         @@RMRF_PATHS = []
@@ -35,5 +35,6 @@ def self.reset
     def self.rm_rf(path)
         FileUtilsStorage.push_rmrf_path(path)
         FileUtilsStorage.increase_rmrfi_invocation_count
+        Dir.remove_mocked_paths(path)
     end
 end

scripts/cocoapods/codegen_utils.rb

@@ -314,6 +314,17 @@ def self.clean_up_build_folder(app_path, codegen_dir)
       return if !Dir.exist?(codegen_path)
 
       FileUtils.rm_rf(Dir.glob("#{codegen_path}/*"))
-      CodegenUtils.set_cleanup_done(true)
+      CodegenUtils.assert_codegen_folder_is_empty(app_path, codegen_dir)
+    end
+
+    # Need to split this function from the previous one to be able to test it properly.
+    def self.assert_codegen_folder_is_empty(app_path, codegen_dir)
+      # double check that the files have actually been deleted.
+      # Emit an error message if not.
+      codegen_path = File.join(app_path, codegen_dir)
+      if Dir.exist?(codegen_path) && Dir.glob("#{codegen_path}/*").length() != 0
+        Pod::UI.warn "Unable to remove the content of #{codegen_path} folder. Please run rm -rf #{codegen_path} and try again."
+        abort
+      end
     end
 end