Merge pull request #1352 from microsoft/dev/lifengl/invalidOperationDuringLoadingSolution

Fix an invalid operation exception when enumerating RarelyRemoveItemSet.

Author: lifengl

src/Microsoft.VisualStudio.Threading/RarelyRemoveItemSet`1.cs

@@ -205,7 +205,7 @@ public bool MoveNext()
 
                     case IndexBeforeFirstArrayElement:
                         this.currentIndex = 0;
-                        return true;
+                        return this.count > 0;
                 }
             }
 

test/Microsoft.VisualStudio.Threading.Tests/RarelyRemoveItemSetTests.cs

@@ -127,6 +127,26 @@ public void RemoveFromTwoFIFO()
         Assert.Empty(this.list.ToArray());
     }
 
+    [Fact]
+    public void RemoveFromTwoEnumeration()
+    {
+        var value1 = new GenericParameterHelper(1);
+        var value2 = new GenericParameterHelper(2);
+        this.list.Add(value1);
+        this.list.Add(value2);
+
+        this.list.Remove(value1);
+        this.list.Remove(value2);
+
+        int count = 0;
+        foreach (GenericParameterHelper item in this.list.EnumerateAndClear())
+        {
+            count++;
+        }
+
+        Assert.Equal(0, count);
+    }
+
     [Fact]
     public void RemoveFromMultiple()
     {