#269 Clean up QueryString APIs, add tests.

src/Microsoft.AspNet.Http.Abstractions/QueryString.cs

@@ -2,6 +2,8 @@
 // Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
 
 using System;
+using System.Collections.Generic;
+using System.Text;
 using Microsoft.Framework.Internal;
 using Microsoft.Framework.WebEncoders;
 
@@ -33,16 +35,6 @@ namespace Microsoft.AspNet.Http
             _value = value;
         }
 
-        /// <summary>
-        /// Initialize a query string with a single given parameter name and value.
-        /// </summary>
-        /// <param name="name">The un-encoded parameter name</param>
-        /// <param name="value">The un-encoded parameter value</param>
-        public QueryString(string name, string value)
-        {
-            _value = "?" + UrlEncoder.Default.UrlEncode(name) + '=' + UrlEncoder.Default.UrlEncode(value);
-        }
-
         /// <summary>
         /// The escaped query string with the leading '?' character
         /// </summary>
@@ -114,6 +106,67 @@ namespace Microsoft.AspNet.Http
             return new QueryString(queryValue);
         }
 
+        /// <summary>
+        /// Create a query string with a single given parameter name and value.
+        /// </summary>
+        /// <param name="name">The un-encoded parameter name</param>
+        /// <param name="value">The un-encoded parameter value</param>
+        public static QueryString Create(string name, string value)
+        {
+            return new QueryString("?" + UrlEncoder.Default.UrlEncode(name) + '=' + UrlEncoder.Default.UrlEncode(value));
+        }
+
+        /// <summary>
+        /// Creates a query string composed from the given name value pairs.
+        /// </summary>
+        /// <param name="parameters"></param>
+        /// <returns></returns>
+        public static QueryString Create(IEnumerable<KeyValuePair<string, string>> parameters)
+        {
+            var builder = new StringBuilder();
+            bool first = true;
+            foreach (var pair in parameters)
+            {
+                builder.Append(first ? "?" : "&");
+                first = false;
+                builder.Append(UrlEncoder.Default.UrlEncode(pair.Key));
+                builder.Append("=");
+                builder.Append(UrlEncoder.Default.UrlEncode(pair.Value));
+            }
+
+            return new QueryString(builder.ToString());
+        }
+
+        public QueryString Add(QueryString other)
+        {
+            if (!HasValue || Value.Equals("?", StringComparison.Ordinal))
+            {
+                return other;
+            }
+            if (!other.HasValue || other.Value.Equals("?", StringComparison.Ordinal))
+            {
+                return this;
+            }
+
+            // ?name1=value1 Add ?name2=value2 returns ?name1=value1&name2=value2
+            return new QueryString(_value + "&" + other.Value.Substring(1));
+        }
+
+        public QueryString Add(string name, string value)
+        {
+            if (!HasValue || Value.Equals("?", StringComparison.Ordinal))
+            {
+                return Create(name, value);
+            }
+
+            var builder = new StringBuilder(Value);
+            builder.Append("&");
+            builder.Append(UrlEncoder.Default.UrlEncode(name));
+            builder.Append("=");
+            builder.Append(UrlEncoder.Default.UrlEncode(value));
+            return new QueryString(builder.ToString());
+        }
+
         public bool Equals(QueryString other)
         {
             return string.Equals(_value, other._value);
@@ -142,5 +195,10 @@ namespace Microsoft.AspNet.Http
         {
             return !left.Equals(right);
         }
+
+        public static QueryString operator +(QueryString left, QueryString right)
+        {
+            return left.Add(right);
+        }
     }
 }

test/Microsoft.AspNet.Http.Abstractions.Tests/QueryStringTests.cs

@@ -0,0 +1,111 @@
+// Copyright (c) .NET Foundation. All rights reserved.
+// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
+
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Threading.Tasks;
+using Microsoft.AspNet.Testing;
+using Xunit;
+
+namespace Microsoft.AspNet.Http.Abstractions
+{
+    public class QueryStringTests
+    {
+        [Fact]
+        public void CtorThrows_IfQueryDoesNotHaveLeadingQuestionMark()
+        {
+            // Act and Assert
+            ExceptionAssert.ThrowsArgument(() => new QueryString("hello"), "value", "The leading '?' must be included for a non-empty query.");
+        }
+
+        [Fact]
+        public void CtorNullOrEmpty_Success()
+        {
+            var query = new QueryString();
+            Assert.False(query.HasValue);
+            Assert.Null(query.Value);
+
+            query = new QueryString(null);
+            Assert.False(query.HasValue);
+            Assert.Null(query.Value);
+
+            query = new QueryString(string.Empty);
+            Assert.False(query.HasValue);
+            Assert.Equal(string.Empty, query.Value);
+        }
+
+        [Fact]
+        public void CtorJustAQuestionMark_Success()
+        {
+            var query = new QueryString("?");
+            Assert.True(query.HasValue);
+            Assert.Equal("?", query.Value);
+        }
+
+        [Fact]
+        public void ToString_EncodesHash()
+        {
+            var query = new QueryString("?Hello=Wor#ld");
+            Assert.Equal("?Hello=Wor%23ld", query.ToString());
+        }
+
+        [Theory]
+        [InlineData("name", "value", "?name=value")]
+        [InlineData("na me", "val ue", "?na%20me=val%20ue")]
+        [InlineData("name", "", "?name=")]
+        [InlineData("", "value", "?=value")]
+        [InlineData("", "", "?=")]
+        [InlineData(null, null, "?=")]
+        public void CreateNameValue_Success(string name, string value, string exepcted)
+        {
+            var query = QueryString.Create(name, value);
+            Assert.Equal(exepcted, query.Value);
+        }
+
+        [Fact]
+        public void CreateFromList_Success()
+        {
+            var query = QueryString.Create(new[]
+            {
+                new KeyValuePair<string, string>("key1", "value1"),
+                new KeyValuePair<string, string>("key2", "value2"),
+                new KeyValuePair<string, string>("key3", "value3"),
+            });
+            Assert.Equal("?key1=value1&key2=value2&key3=value3", query.Value);
+        }
+
+        [Theory]
+        [InlineData(null, null, null)]
+        [InlineData("", "", "")]
+        [InlineData(null, "?name2=value2", "?name2=value2")]
+        [InlineData("", "?name2=value2", "?name2=value2")]
+        [InlineData("?", "?name2=value2", "?name2=value2")]
+        [InlineData("?name1=value1", null, "?name1=value1")]
+        [InlineData("?name1=value1", "", "?name1=value1")]
+        [InlineData("?name1=value1", "?", "?name1=value1")]
+        [InlineData("?name1=value1", "?name2=value2", "?name1=value1&name2=value2")]
+        public void AddQueryString_Success(string query1, string query2, string expected)
+        {
+            var q1 = new QueryString(query1);
+            var q2 = new QueryString(query2);
+            Assert.Equal(expected, q1.Add(q2).Value);
+            Assert.Equal(expected, (q1 + q2).Value);
+        }
+
+        [Theory]
+        [InlineData(null, null, null, "?=")]
+        [InlineData("", "", "", "?=")]
+        [InlineData("?", "", "", "?=")]
+        [InlineData("?", "name2", "value2", "?name2=value2")]
+        [InlineData("?name1=value1", "name2", "value2", "?name1=value1&name2=value2")]
+        [InlineData("?name1=value1", "na me2", "val ue2", "?name1=value1&na%20me2=val%20ue2")]
+        [InlineData("?name1=value1", "", "", "?name1=value1&=")]
+        public void AddNameValue_Success(string query1, string name2, string value2, string expected)
+        {
+            var q1 = new QueryString(query1);
+            var q2 = q1.Add(name2, value2);
+            Assert.Equal(expected, q2.Value);
+        }
+    }
+}