Refactored archive code into a service so that I can write tests for it.

API.Tests/Services/ArchiveServiceTests.cs

@@ -0,0 +1,37 @@
+using System.IO;
+using System.IO.Compression;
+using API.Extensions;
+using API.Interfaces;
+using API.Services;
+using Microsoft.Extensions.Logging;
+using NSubstitute;
+using Xunit;
+
+namespace API.Tests.Services
+{
+    public class ArchiveServiceTests
+    {
+        private readonly IArchiveService _archiveService;
+        private readonly ILogger<ArchiveService> _logger = Substitute.For<ILogger<ArchiveService>>();
+
+        private readonly string _testDirectory =
+            Path.Join(Directory.GetCurrentDirectory(), "../../../Services/Test Data/ArchiveService");
+
+        public ArchiveServiceTests()
+        {
+            _archiveService = new ArchiveService(_logger);
+        }
+
+        [Theory]
+        [InlineData("flat file.zip", false)]
+        [InlineData("file in folder in folder.zip", true)]
+        [InlineData("file in folder.zip", true)]
+        [InlineData("file in folder_alt.zip", true)]
+        public void ArchiveNeedsFlatteningTest(string archivePath, bool expected)
+        {
+            var file = Path.Join(_testDirectory, archivePath);
+            using ZipArchive archive = ZipFile.OpenRead(file);
+            Assert.Equal(expected, _archiveService.ArchiveNeedsFlattening(archive));
+        }
+    }
+}