Adding SnapshotAssert

2023-10-13 19:13:07 +02:00
parent 105080ef09
commit e35d86c1ad
2 changed files with 94 additions and 0 deletions
--- a/AMWD.Common.Test/SnapshotAssert.cs
+++ b/AMWD.Common.Test/SnapshotAssert.cs
@@ -0,0 +1,87 @@
+using System.IO;
+using System.Linq;
+using System.Runtime.CompilerServices;
+using System.Text;
+using Microsoft.VisualStudio.TestTools.UnitTesting;
+
+namespace AMWD.Common.Test
+{
+	/// <summary>
+	/// Implements a snapshot comparison for content aggregation (e.g. files).
+	/// </summary>
+	public sealed class SnapshotAssert
+	{
+		/// <summary>
+		/// Tests whether the specified string is equal to the saved snapshot.
+		/// </summary>
+		/// <param name="actual">The current aggregated content string.</param>
+		/// <param name="message">An error message.</param>
+		/// <param name="callerFilePath">The absolute file path of the calling file (filled automatically by the compiler service).</param>
+		/// <param name="callerMemberName">The name of the calling method (filled automatically by the compiler service).</param>
+		public static void AreEqual(string actual, string message = null, [CallerFilePath] string callerFilePath = null, [CallerMemberName] string callerMemberName = null)
+		{
+			string cleanLineEnding = actual
+				.Replace("\r\n", "\n")   // Windows
+				.Replace("\r", "\n");    // old MacOS
+			AreEqual(Encoding.UTF8.GetBytes(cleanLineEnding), message, callerFilePath, callerMemberName);
+		}
+
+		/// <summary>
+		/// Tests whether the specified byte array is equal to the saved snapshot.
+		/// </summary>
+		/// <param name="actual">The current aggregated content bytes.</param>
+		/// <param name="message">An error message.</param>
+		/// <param name="callerFilePath">The absolute file path of the calling file (filled automatically by the compiler service).</param>
+		/// <param name="callerMemberName">The name of the calling method (filled automatically by the compiler service).</param>
+		public static void AreEqual(byte[] actual, string message = null, [CallerFilePath] string callerFilePath = null, [CallerMemberName] string callerMemberName = null)
+			=> AreEqual(actual, 0, -1, message, callerFilePath, callerMemberName);
+
+		/// <summary>
+		/// Tests whether the specified byte array is equal to the saved snapshot.
+		/// </summary>
+		/// <remarks>
+		/// The past has shown, that e.g. wkhtmltopdf prints the current timestamp at the beginning of the PDF file.
+		/// Therefore only a specific part of that file can be asserted to be equal.
+		/// </remarks>
+		/// <param name="actual">The current aggregated content bytes.</param>
+		/// <param name="firstByteIndex">The first byte to compare.</param>
+		/// <param name="lastByteIndex">The last byte to compare.</param>
+		/// <param name="message">An error message.</param>
+		/// <param name="callerFilePath">The absolute file path of the calling file (filled automatically by the compiler service).</param>
+		/// <param name="callerMemberName">The name of the calling method (filled automatically by the compiler service).</param>
+		public static void AreEqual(byte[] actual, int firstByteIndex, int lastByteIndex, string message = null, [CallerFilePath] string callerFilePath = null, [CallerMemberName] string callerMemberName = null)
+		{
+			string callerDir = Path.GetDirectoryName(callerFilePath);
+			string callerFile = Path.GetFileNameWithoutExtension(callerFilePath);
+
+			string snapshotDir = Path.Combine(callerDir, "Snapshots", callerFile);
+			string snapshotFile = Path.Combine(snapshotDir, $"{callerMemberName}.snap");
+
+			if (File.Exists(snapshotFile))
+			{
+				byte[] expected = File.ReadAllBytes(snapshotFile);
+
+				var actualBytes = actual.Skip(firstByteIndex);
+				var expectedBytes = expected.Skip(firstByteIndex);
+
+				if (lastByteIndex > firstByteIndex)
+				{
+					actualBytes = actualBytes.Take(lastByteIndex - firstByteIndex);
+					expectedBytes = expectedBytes.Take(lastByteIndex - firstByteIndex);
+				}
+
+				if (message == null)
+					CollectionAssert.AreEqual(expectedBytes.ToArray(), actualBytes.ToArray());
+				else
+					CollectionAssert.AreEqual(expectedBytes.ToArray(), actualBytes.ToArray(), message);
+			}
+			else
+			{
+				if (!Directory.Exists(snapshotDir))
+					Directory.CreateDirectory(snapshotDir);
+
+				File.WriteAllBytes(snapshotFile, actual);
+			}
+		}
+	}
+}