diff --git a/test/Microsoft.Framework.Primitives.Tests/StringValuesTests.cs b/test/Microsoft.Framework.Primitives.Tests/StringValuesTests.cs
index 389d6f547d..bdf8e7bca3 100644
--- a/test/Microsoft.Framework.Primitives.Tests/StringValuesTests.cs
+++ b/test/Microsoft.Framework.Primitives.Tests/StringValuesTests.cs
@@ -2,6 +2,7 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections;
 using System.Collections.Generic;
 using System.Linq;
 using Xunit;
@@ -10,10 +11,76 @@ namespace Microsoft.Framework.Primitives
 {
     public class StringValuesTests
     {
-        [Fact]
-        public void IsReadOnly_True()
+        public static TheoryData<StringValues> DefaultOrNullStringValues
+        {
+            get
+            {
+                return new TheoryData<StringValues>
+                {
+                    new StringValues(),
+                    new StringValues((string)null),
+                    new StringValues((string[])null),
+                    (string)null,
+                    (string[])null
+                };
+            }
+        }
+
+        public static TheoryData<StringValues> EmptyStringValues
+        {
+            get
+            {
+                return new TheoryData<StringValues>
+                {
+                    StringValues.Empty,
+                    new StringValues(new string[0]),
+                    new string[0]
+                };
+            }
+        }
+
+        public static TheoryData<StringValues> FilledStringValues
+        {
+            get
+            {
+                return new TheoryData<StringValues>
+                {
+                    new StringValues("abc"),
+                    new StringValues(new[] { "abc" }),
+                    new StringValues(new[] { "abc", "bcd" }),
+                    new StringValues(new[] { "abc", "bcd", "foo" }),
+                    "abc",
+                    new[] { "abc" },
+                    new[] { "abc", "bcd" },
+                    new[] { "abc", "bcd", "foo" }
+                };
+            }
+        }
+
+        public static TheoryData<StringValues, string[]> FilledStringValuesWithExpected
+        {
+            get
+            {
+                return new TheoryData<StringValues, string[]>
+                {
+                    { new StringValues("abc"), new[] { "abc" } },
+                    { new StringValues(new[] { "abc" }), new[] { "abc" } },
+                    { new StringValues(new[] { "abc", "bcd" }), new[] { "abc", "bcd" } },
+                    { new StringValues(new[] { "abc", "bcd", "foo" }), new[] { "abc", "bcd", "foo" } },
+                    { "abc", new[] { "abc" } },
+                    { new[] { "abc" }, new[] { "abc" } },
+                    { new[] { "abc", "bcd" }, new[] { "abc", "bcd" } },
+                    { new[] { "abc", "bcd", "foo" }, new[] { "abc", "bcd", "foo" } }
+                };
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(DefaultOrNullStringValues))]
+        [MemberData(nameof(EmptyStringValues))]
+        [MemberData(nameof(FilledStringValues))]
+        public void IsReadOnly_True(StringValues stringValues)
         {
-            var stringValues = new StringValues();
             Assert.True(((IList<string>)stringValues).IsReadOnly);
             Assert.Throws<NotSupportedException>(() => ((IList<string>)stringValues)[0] = string.Empty);
             Assert.Throws<NotSupportedException>(() => ((ICollection<string>)stringValues).Add(string.Empty));
@@ -23,51 +90,34 @@ namespace Microsoft.Framework.Primitives
             Assert.Throws<NotSupportedException>(() => ((ICollection<string>)stringValues).Clear());
         }
 
-        [Fact]
-        public void DefaultConstructor_ExpectedValues()
+        [Theory]
+        [MemberData(nameof(DefaultOrNullStringValues))]
+        public void DefaultOrNull_ExpectedValues(StringValues stringValues)
+        {
+            Assert.Null((string[])stringValues);
+        }
+
+        [Theory]
+        [MemberData(nameof(DefaultOrNullStringValues))]
+        [MemberData(nameof(EmptyStringValues))]
+        public void DefaultNullOrEmpty_ExpectedValues(StringValues stringValues)
         {
-            var stringValues = new StringValues();
             Assert.Equal(0, stringValues.Count);
+            Assert.Null((string)stringValues);
             Assert.Equal((string)null, stringValues);
+            Assert.Equal(string.Empty, stringValues.ToString());
             Assert.Equal(new string[0], stringValues.ToArray());
 
             Assert.True(StringValues.IsNullOrEmpty(stringValues));
             Assert.Throws<IndexOutOfRangeException>(() => stringValues[0]);
+            Assert.Throws<IndexOutOfRangeException>(() => ((IList<string>)stringValues)[0]);
             Assert.Equal(string.Empty, stringValues.ToString());
+            Assert.Equal(-1, ((IList<string>)stringValues).IndexOf(null));
             Assert.Equal(-1, ((IList<string>)stringValues).IndexOf(string.Empty));
-            Assert.Equal(0, stringValues.Count());
-        }
-
-        [Fact]
-        public void Constructor_NullStringValue_ExpectedValues()
-        {
-            var stringValues = new StringValues((string)null);
-            Assert.Equal(0, stringValues.Count);
-            Assert.Null((string)stringValues);
-            Assert.Equal(string.Empty, stringValues.ToString());
-            Assert.Null((string[])stringValues);
-            Assert.Equal(new string[0], stringValues.ToArray());
-
-            Assert.True(StringValues.IsNullOrEmpty(stringValues));
-            Assert.Throws<IndexOutOfRangeException>(() => stringValues[0]);
-            Assert.Equal(-1, ((IList<string>)stringValues).IndexOf(string.Empty));
-            Assert.Equal(0, stringValues.Count());
-        }
-
-        [Fact]
-        public void Constructor_NullStringArray_ExpectedValues()
-        {
-            var stringValues = new StringValues((string[])null);
-            Assert.Equal(0, stringValues.Count);
-            Assert.Null((string)stringValues);
-            Assert.Equal(string.Empty, stringValues.ToString());
-            Assert.Null((string[])stringValues);
-            Assert.Equal(new string[0], stringValues.ToArray());
-
-            Assert.True(StringValues.IsNullOrEmpty(stringValues));
-            Assert.Throws<IndexOutOfRangeException>(() => stringValues[0]);
-            Assert.Equal(string.Empty, stringValues.ToString());
-            Assert.Equal(-1, ((IList<string>)stringValues).IndexOf(string.Empty));
+            Assert.Equal(-1, ((IList<string>)stringValues).IndexOf("not there"));
+            Assert.False(((ICollection<string>)stringValues).Contains(null));
+            Assert.False(((ICollection<string>)stringValues).Contains(string.Empty));
+            Assert.False(((ICollection<string>)stringValues).Contains("not there"));
             Assert.Equal(0, stringValues.Count());
         }
 
@@ -85,6 +135,7 @@ namespace Microsoft.Framework.Primitives
             Assert.Equal(1, stringValues.Count);
             Assert.Equal(aString, stringValues);
             Assert.Equal(aString, stringValues[0]);
+            Assert.Equal(aString, ((IList<string>)stringValues)[0]);
             Assert.Equal<string[]>(new string[] { aString }, stringValues);
         }
 
@@ -103,6 +154,7 @@ namespace Microsoft.Framework.Primitives
             Assert.Equal(1, stringValues.Count);
             Assert.Equal(aString, stringValues);
             Assert.Equal(aString, stringValues[0]);
+            Assert.Equal(aString, ((IList<string>)stringValues)[0]);
             Assert.Equal<string[]>(aStringArray, stringValues);
 
             aString = "abc";
@@ -113,5 +165,117 @@ namespace Microsoft.Framework.Primitives
             Assert.Equal("abc,bcd", stringValues);
             Assert.Equal<string[]>(aStringArray, stringValues);
         }
+
+        [Theory]
+        [MemberData(nameof(DefaultOrNullStringValues))]
+        [MemberData(nameof(EmptyStringValues))]
+        public void DefaultNullOrEmpty_Enumerator(StringValues stringValues)
+        {
+            var e1 = ((IEnumerable<string>)stringValues).GetEnumerator();
+            Assert.Null(e1.Current);
+            Assert.False(e1.MoveNext());
+            Assert.Null(e1.Current);
+            Assert.False(e1.MoveNext());
+            Assert.False(e1.MoveNext());
+            Assert.False(e1.MoveNext());
+
+            var e2 = ((IEnumerable)stringValues).GetEnumerator();
+            Assert.Null(e2.Current);
+            Assert.False(e2.MoveNext());
+            Assert.Null(e2.Current);
+            Assert.False(e2.MoveNext());
+            Assert.False(e2.MoveNext());
+            Assert.False(e2.MoveNext());
+        }
+
+        [Theory]
+        [MemberData(nameof(FilledStringValuesWithExpected))]
+        public void Enumerator(StringValues stringValues, string[] expected)
+        {
+            var e1 = ((IEnumerable<string>)stringValues).GetEnumerator();
+            Assert.Null(e1.Current);
+            for (int i = 0; i < expected.Length; i++)
+            {
+                Assert.True(e1.MoveNext());
+                Assert.Equal(expected[i], e1.Current);
+            }
+            Assert.False(e1.MoveNext());
+            Assert.False(e1.MoveNext());
+            Assert.False(e1.MoveNext());
+
+            var e2 = ((IEnumerable)stringValues).GetEnumerator();
+            Assert.Null(e2.Current);
+            for (int i = 0; i < expected.Length; i++)
+            {
+                Assert.True(e2.MoveNext());
+                Assert.Equal(expected[i], e2.Current);
+            }
+            Assert.False(e2.MoveNext());
+            Assert.False(e2.MoveNext());
+            Assert.False(e2.MoveNext());
+        }
+
+        [Theory]
+        [MemberData(nameof(FilledStringValuesWithExpected))]
+        public void IndexOf(StringValues stringValues, string[] expected)
+        {
+            IList<string> list = stringValues;
+            Assert.Equal(-1, list.IndexOf("not there"));
+            for (int i = 0; i < expected.Length; i++)
+            {
+                Assert.Equal(i, list.IndexOf(expected[i]));
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(FilledStringValuesWithExpected))]
+        public void Contains(StringValues stringValues, string[] expected)
+        {
+            ICollection<string> collection = stringValues;
+            Assert.False(collection.Contains("not there"));
+            for (int i = 0; i < expected.Length; i++)
+            {
+                Assert.True(collection.Contains(expected[i]));
+            }
+        }
+
+        [Theory]
+        [MemberData(nameof(FilledStringValuesWithExpected))]
+        public void CopyTo(StringValues stringValues, string[] expected)
+        {
+            ICollection<string> collection = stringValues;
+            string[] actual = new string[expected.Length];
+            collection.CopyTo(actual, 0);
+            Assert.Equal(expected, actual);
+        }
+
+        [Theory]
+        [MemberData(nameof(DefaultOrNullStringValues))]
+        [MemberData(nameof(EmptyStringValues))]
+        public void DefaultNullOrEmpty_Concat(StringValues stringValues)
+        {
+            string[] expected = new[] { "abc", "bcd", "foo" };
+            Assert.Equal(expected, StringValues.Concat(stringValues, new StringValues(expected)));
+            Assert.Equal(expected, StringValues.Concat(new StringValues(expected), stringValues));
+
+            string[] empty = new string[0];
+            Assert.Equal(empty, StringValues.Concat(stringValues, StringValues.Empty));
+            Assert.Equal(empty, StringValues.Concat(StringValues.Empty, stringValues));
+            Assert.Equal(empty, StringValues.Concat(stringValues, new StringValues()));
+            Assert.Equal(empty, StringValues.Concat(new StringValues(), stringValues));
+        }
+
+        [Theory]
+        [MemberData(nameof(FilledStringValuesWithExpected))]
+        public void Concat(StringValues stringValues, string[] array)
+        {
+            string[] filled = new[] { "abc", "bcd", "foo" };
+
+            string[] expectedPrepended = array.Concat(filled).ToArray();
+            Assert.Equal(expectedPrepended, StringValues.Concat(stringValues, new StringValues(filled)));
+
+            string[] expectedAppended = filled.Concat(array).ToArray();
+            Assert.Equal(expectedAppended, StringValues.Concat(new StringValues(filled), stringValues));
+        }
     }
 }