Improve test coverage and type of exceptions thrown for unsuported stuff

Author: georg-jung

src/FastBertTokenizer.Tests/BatchEnumerators.cs

@@ -34,6 +34,30 @@ public void TokenizeWithBatchEnumerator(Dictionary<int, string> articles)
         }
     }
 
+    [Theory]
+    [MemberData(nameof(WikipediaSimpleData.GetArticlesDict), MemberType = typeof(WikipediaSimpleData))]
+    public void TokenizeWithBatchEnumeratorNonGenericEnumerable(Dictionary<int, string> articles)
+    {
+        IEnumerable<(int, string)> Source()
+        {
+            foreach (var (key, value) in articles.Take(100)) // some data is sufficient here, as TokenizeWithBatchEnumerator already checks the same.
+            {
+                yield return (key, value);
+            }
+        }
+
+        var enumerable = (System.Collections.IEnumerable)_uut.CreateBatchEnumerator(Source(), 512, 10, 0);
+        foreach (var batch in enumerable)
+        {
+            var casted = (TokenizedBatch<int>)batch;
+            casted.InputIds.Span[0].ShouldBe(101); // [CLS] = 101
+        }
+
+        var anotherEnumerable = (System.Collections.IEnumerable)_uut.CreateBatchEnumerator(Source(), 512, 10, 0);
+        var enumerator = anotherEnumerable.GetEnumerator();
+        Should.Throw<InvalidOperationException>(enumerator.Reset);
+    }
+
     [Theory]
     [MemberData(nameof(WikipediaSimpleData.GetArticlesDict), MemberType = typeof(WikipediaSimpleData))]
     public async Task TokenizeWithAsyncBatchEnumerator(Dictionary<int, string> articles)

src/FastBertTokenizer/AsyncBatchEnumerator.cs

@@ -147,15 +147,15 @@ public bool MoveNext()
             var vt = parent.MoveNextAsync();
             if (!vt.IsCompletedSuccessfully)
             {
-                throw new NotImplementedException();
+                throw new NotImplementedException(); // UnreachableException is only available in .NET 7+
             }
             else
             {
                 return vt.Result;
             }
         }
 
-        public void Reset() => throw new InvalidOperationException("Multiple enumeration is not supported.");
+        public void Reset() => throw new NotSupportedException("Multiple enumeration is not supported.");
     }
 }