Improving name generation in MSTest

src/Snapshooter.MSTest/MSTestSnapshotFullNameReader.cs

@@ -1,4 +1,5 @@
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Diagnostics;
 using System.IO;
@@ -130,9 +131,21 @@ private static string GetMethodSnapshotName(MethodBase method)
             DataRowAttribute currentRow =
                 dataRowAttributes.ElementAt(dataTestMethodRowIndex[method.Name]);
 
+            if (!string.IsNullOrEmpty(currentRow.DisplayName))
+            {
+                return $"{method.DeclaringType.Name}.{currentRow.DisplayName}";
+            }
+
             return $"{method.DeclaringType.Name}." +
                 method.Name +
-                $"_{string.Join("_", currentRow.Data.Select(d => d.ToString()))}";
+                $"_{string.Join("_", currentRow.Data.Select(ParamDataFormatter))}";
         }
+
+        private static string ParamDataFormatter(object data) => data switch
+        {
+            var d when d is null => "null",
+            var d when d is IEnumerable => $"[{string.Join("_", (IEnumerable<object>)d)}]",
+            _ => data.ToString()
+        };
     }
 }

src/Snapshooter/SnapshotFullName.cs

@@ -1,4 +1,6 @@
-namespace Snapshooter
+using System.IO;
+
+namespace Snapshooter
 {
     /// <summary>
     /// The snapshot full name instance contains the file name and the path
@@ -14,6 +16,13 @@ public class SnapshotFullName
         /// <param name="folderPath">The folder path.</param>
         public SnapshotFullName(string fileName, string folderPath)
         {
+            char[] invalidChars = Path.GetInvalidFileNameChars();
+
+            foreach (char invalidChar in invalidChars)
+            {
+                fileName = fileName.Replace(invalidChar, '_');
+            }
+
             Filename = fileName;
             FolderPath = folderPath;
         }

test/Snapshooter.MSTest.Tests/MSTestSnapshotFullNameReaderTests.cs

@@ -1,3 +1,4 @@
+using System.Collections.Generic;
 using System.Threading.Tasks;
 using Microsoft.VisualStudio.TestTools.UnitTesting;
 
@@ -118,6 +119,49 @@ public async Task ReadSnapshotFullName_ResolveTheoryDataSnapshotNameAsync_NameRe
                 $"_{param1}_{param2}");
         }
 
+        [DataTestMethod]
+        [DataRow("testString1", 5)]
+        [DataRow("testString2", 6)]
+        [DataRow("testString3", null)]
+        public async Task ReadSnapshotFullName_ResolveTheorySnapshotNameAsync_NameResolvedWithNullParameters(
+           string param1, int? param2)
+        {
+            // arrange
+            var snapshotFullNameResolver = new MSTestSnapshotFullNameReader();
+            await Task.Delay(1);
+
+            // act
+            SnapshotFullName snapshotFullName = snapshotFullNameResolver.ReadSnapshotFullName();
+
+            // assert
+            await Task.Delay(1);
+            Assert.AreEqual(snapshotFullName.Filename,
+                $"{nameof(MSTestSnapshotFullNameReaderTests)}." +
+                $"{nameof(ReadSnapshotFullName_ResolveTheorySnapshotNameAsync_NameResolvedWithNullParameters)}" +
+                $"_{param1}_{(param2 is null ? "null" : param2)}");
+        }
+
+        [DataTestMethod]
+        [DataRow(new string[] { })]
+        [DataRow(new string[] { "a" })]
+        public async Task ReadSnapshotFullName_ResolveTheorySnapshotNameAsync_NameResolvedCollectionParameters(
+           object param)
+        {
+            // arrange
+            var snapshotFullNameResolver = new MSTestSnapshotFullNameReader();
+            await Task.Delay(1);
+
+            // act
+            SnapshotFullName snapshotFullName = snapshotFullNameResolver.ReadSnapshotFullName();
+
+            // assert
+            await Task.Delay(1);
+            Assert.AreEqual(snapshotFullName.Filename,
+                $"{nameof(MSTestSnapshotFullNameReaderTests)}." +
+                $"{nameof(ReadSnapshotFullName_ResolveTheorySnapshotNameAsync_NameResolvedCollectionParameters)}" +
+                $"_[{string.Join("_", (IEnumerable<object>)param)}]");
+        }
+
         private static object[] TestCases => new object[]
         {
             new object[] { "testString1", 5 },