Add tests.

src/Workspaces/CoreTest/UtilityTest/EditDistanceTests.cs

@@ -7,92 +7,121 @@ namespace Microsoft.CodeAnalysis.UnitTests
 {
     public class EditDistanceTests
     {
-        private static int GetEditDistance(string s, string t)
+        private static int VerifyEditDistance(string s, string t)
         {
             // We want the full edit distance, without bailing out early because we crossed the
             // threshold.
-            return EditDistance.GetEditDistance(s, t);
+            var editDistance1 = EditDistance.GetEditDistance(s, t);
+            var editDistance2 = EditDistance.GetEditDistance(s, t, editDistance1);
+
+            Assert.Equal(editDistance1, editDistance2);
+
+            return editDistance1;
         }
 
         [Fact]
         public void EditDistance0()
         {
-            Assert.Equal(GetEditDistance("", ""), 0);
-            Assert.Equal(GetEditDistance("a", "a"), 0);
+            Assert.Equal(VerifyEditDistance("", ""), 0);
+            Assert.Equal(VerifyEditDistance("a", "a"), 0);
         }
 
         [Fact]
         public void EditDistance1()
         {
-            Assert.Equal(GetEditDistance("", "a"), 1);
-            Assert.Equal(GetEditDistance("a", ""), 1);
-            Assert.Equal(GetEditDistance("a", "b"), 1);
-            Assert.Equal(GetEditDistance("ab", "a"), 1);
-            Assert.Equal(GetEditDistance("a", "ab"), 1);
-            Assert.Equal(GetEditDistance("aabb", "abab"), 1);
+            Assert.Equal(VerifyEditDistance("", "a"), 1);
+            Assert.Equal(VerifyEditDistance("a", ""), 1);
+            Assert.Equal(VerifyEditDistance("a", "b"), 1);
+            Assert.Equal(VerifyEditDistance("ab", "a"), 1);
+            Assert.Equal(VerifyEditDistance("a", "ab"), 1);
+            Assert.Equal(VerifyEditDistance("aabb", "abab"), 1);
         }
 
         [Fact]
         public void EditDistance2()
         {
-            Assert.Equal(GetEditDistance("", "aa"), 2);
-            Assert.Equal(GetEditDistance("aa", ""), 2);
-            Assert.Equal(GetEditDistance("aa", "bb"), 2);
-            Assert.Equal(GetEditDistance("aab", "a"), 2);
-            Assert.Equal(GetEditDistance("a", "aab"), 2);
-            Assert.Equal(GetEditDistance("aababb", "ababab"), 2);
+            Assert.Equal(VerifyEditDistance("", "aa"), 2);
+            Assert.Equal(VerifyEditDistance("aa", ""), 2);
+            Assert.Equal(VerifyEditDistance("aa", "bb"), 2);
+            Assert.Equal(VerifyEditDistance("aab", "a"), 2);
+            Assert.Equal(VerifyEditDistance("a", "aab"), 2);
+            Assert.Equal(VerifyEditDistance("aababb", "ababab"), 2);
         }
 
         [Fact]
         public void EditDistance3()
         {
-            Assert.Equal(GetEditDistance("", "aaa"), 3);
-            Assert.Equal(GetEditDistance("aaa", ""), 3);
-            Assert.Equal(GetEditDistance("aaa", "bbb"), 3);
-            Assert.Equal(GetEditDistance("aaab", "a"), 3);
-            Assert.Equal(GetEditDistance("a", "aaab"), 3);
-            Assert.Equal(GetEditDistance("aababbab", "abababaa"), 3);
+            Assert.Equal(VerifyEditDistance("", "aaa"), 3);
+            Assert.Equal(VerifyEditDistance("aaa", ""), 3);
+            Assert.Equal(VerifyEditDistance("aaa", "bbb"), 3);
+            Assert.Equal(VerifyEditDistance("aaab", "a"), 3);
+            Assert.Equal(VerifyEditDistance("a", "aaab"), 3);
+            Assert.Equal(VerifyEditDistance("aababbab", "abababaa"), 3);
         }
 
         [Fact]
         public void EditDistance4()
         {
-            Assert.Equal(GetEditDistance("XlmReade", "XmlReader"), 2);
+            Assert.Equal(VerifyEditDistance("XlmReade", "XmlReader"), 2);
         }
 
         public void EditDistance5()
         {
-            Assert.Equal(GetEditDistance("Zeil", "trials"), 4);
+            Assert.Equal(VerifyEditDistance("Zeil", "trials"), 4);
         }
 
         [Fact]
         public void EditDistance6()
         {
-            Assert.Equal(GetEditDistance("barking", "corkliness"), 6);
+            Assert.Equal(VerifyEditDistance("barking", "corkliness"), 6);
         }
 
         [Fact]
         public void EditDistance7()
         {
-            Assert.Equal(GetEditDistance("kitten", "sitting"), 3);
+            Assert.Equal(VerifyEditDistance("kitten", "sitting"), 3);
         }
 
         [Fact]
         public void EditDistance8()
         {
-            Assert.Equal(GetEditDistance("sunday", "saturday"), 3);
+            Assert.Equal(VerifyEditDistance("sunday", "saturday"), 3);
         }
 
         [Fact]
         public void EditDistance9()
         {
-            Assert.Equal(GetEditDistance("meilenstein", "levenshtein"), 4);
+            Assert.Equal(VerifyEditDistance("meilenstein", "levenshtein"), 4);
         }
 
         [Fact]
         public void EditDistance10()
         {
-            Assert.Equal(GetEditDistance("rosettacode", "raisethysword"), 8);
+            Assert.Equal(VerifyEditDistance("rosettacode", "raisethysword"), 8);
+        }
+
+        [Fact]
+        public void EditDistance11()
+        {
+            Assert.Equal(VerifyEditDistance("aaaab", "aaabc"), 2);
+            Assert.Equal(VerifyEditDistance("aaaab", "aabcc"), 3);
+            Assert.Equal(VerifyEditDistance("aaaab", "abccc"), 4);
+            Assert.Equal(VerifyEditDistance("aaaab", "bcccc"), 5);
+
+            Assert.Equal(VerifyEditDistance("aaaabb", "aaabbc"), 2);
+            Assert.Equal(VerifyEditDistance("aaaabb", "aabbcc"), 4);
+            Assert.Equal(VerifyEditDistance("aaaabb", "abbccc"), 5);
+            Assert.Equal(VerifyEditDistance("aaaabb", "bbcccc"), 6);
+
+            Assert.Equal(VerifyEditDistance("aaaabbb", "aaabbbc"), 2);
+            Assert.Equal(VerifyEditDistance("aaaabbb", "aabbbcc"), 4);
+            Assert.Equal(VerifyEditDistance("aaaabbb", "abbbccc"), 6);
+            Assert.Equal(VerifyEditDistance("aaaabbb", "bbbcccc"), 7);
+
+            Assert.Equal(VerifyEditDistance("aaaabbbb", "aaabbbbc"), 2);
+            Assert.Equal(VerifyEditDistance("aaaabbbb", "aabbbbcc"), 4);
+            Assert.Equal(VerifyEditDistance("aaaabbbb", "abbbbccc"), 6);
+            Assert.Equal(VerifyEditDistance("aaaabbbb", "bbbbcccc"), 8);
         }
 
         [Fact]
@@ -109,7 +138,7 @@ public void TestMetric()
             // OSA(CA,AC) + OSA(AC,ABC) >= OSA(CA,ABC)  ...   1 + 1 >= 3    is not true.
             //
             // Being a metric is important so that we can properly use this with BKTrees.
-            Assert.Equal(GetEditDistance("CA", "ABC"), 2);
+            Assert.Equal(VerifyEditDistance("CA", "ABC"), 2);
         }
     }
 }