Entryのモデルスペックを追加した

spec/models/entry_spec.rb

@@ -25,4 +25,71 @@
       expect(entry.errors[:image]).to include('対応していない形式のファイルです')
     end
   end
+
+  describe '.validate_mime_type' do
+    let(:allowed_file) { Struct.new(:content_type, :original_filename).new('image/jpeg', 'image.jpg') }
+
+    context 'when all files have allowed MIME types' do
+      it 'returns nil' do
+        files = [allowed_file]
+        expect(described_class.validate_mime_type(files)).to be_nil
+      end
+    end
+
+    context 'when some files have disallowed MIME types' do
+      it 'returns an error message' do
+        disallowed_file = Struct.new(:content_type, :original_filename).new('text/plain', 'file.txt')
+        files = [allowed_file, disallowed_file]
+        expect(described_class.validate_mime_type(files)).to eq('対応していない形式のファイルが含まれています。画面を更新してやり直してください。')
+      end
+    end
+
+    context 'when files array is empty' do
+      it 'returns nil' do
+        files = []
+        expect(described_class.validate_mime_type(files)).to be_nil
+      end
+    end
+  end
+
+  describe '.determine_mime_type' do
+    context 'when content_type is application/octet-stream' do
+      it 'returns image/jpeg for .jpg' do
+        file = Struct.new(:content_type, :original_filename).new('application/octet-stream', 'image.jpg')
+        expect(described_class.determine_mime_type(file)).to eq('image/jpeg')
+      end
+
+      it 'returns image/png for .png' do
+        file = Struct.new(:content_type, :original_filename).new('application/octet-stream', 'image.png')
+        expect(described_class.determine_mime_type(file)).to eq('image/png')
+      end
+
+      it 'returns image/webp for .webp' do
+        file = Struct.new(:content_type, :original_filename).new('application/octet-stream', 'image.webp')
+        expect(described_class.determine_mime_type(file)).to eq('image/webp')
+      end
+
+      it 'returns image/heic for .heic' do
+        file = Struct.new(:content_type, :original_filename).new('application/octet-stream', 'image.heic')
+        expect(described_class.determine_mime_type(file)).to eq('image/heic')
+      end
+
+      it 'returns image/heif for .heif' do
+        file = Struct.new(:content_type, :original_filename).new('application/octet-stream', 'image.heif')
+        expect(described_class.determine_mime_type(file)).to eq('image/heif')
+      end
+
+      it 'returns application/octet-stream for unsupported extension' do
+        file = Struct.new(:content_type, :original_filename).new('application/octet-stream', 'file.txt')
+        expect(described_class.determine_mime_type(file)).to eq('application/octet-stream')
+      end
+    end
+
+    context 'when content_type is not application/octet-stream' do
+      it 'returns the original content_type' do
+        file = Struct.new(:content_type, :original_filename).new('image/jpeg', 'image.jpeg')
+        expect(described_class.determine_mime_type(file)).to eq('image/jpeg')
+      end
+    end
+  end
 end