Improve PathString <-> string logic

Author: HaoK

src/Microsoft.AspNetCore.Http.Abstractions/PathString.cs

@@ -443,25 +443,35 @@ public override int GetHashCode()
  /// </summary>
  /// <param name="s"></param>
  public static implicit operator PathString(string s)
- {
- return new PathString(s);
- }
+ => ConvertFromString(s);
 
  /// <summary>
  /// Implicitly calls ToString().
  /// </summary>
  /// <param name="path"></param>
  public static implicit operator string(PathString path)
- {
- return path.ToString();
- }
+ => path.ToString();
+
+ internal static PathString ConvertFromString(string s)
+ => string.IsNullOrEmpty(s) ? new PathString(s) : FromUriComponent(s);
  }
 
  internal class PathStringConverter : TypeConverter
  {
+ public override bool CanConvertFrom(ITypeDescriptorContext context, Type sourceType)
+ => sourceType == typeof(string) 
+ ? true 
+ : base.CanConvertFrom(context, sourceType);
+
  public override object ConvertFrom(ITypeDescriptorContext context, CultureInfo culture, object value)
- {
- return new PathString((string)value);
- }
+ => value is string 
+ ? PathString.ConvertFromString((string)value) 
+ : base.ConvertFrom(context, culture, value);
+
+ public override object ConvertTo(ITypeDescriptorContext context,
+ CultureInfo culture, object value, Type destinationType)
+ => destinationType == typeof(string) 
+ ? value.ToString() 
+ : base.ConvertTo(context, culture, value, destinationType);
  }
 }

test/Microsoft.AspNetCore.Http.Abstractions.Tests/PathStringTests.cs

@@ -1,4 +1,4 @@
-// Copyright (c) .NET Foundation. All rights reserved.
+// 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;
@@ -208,11 +208,27 @@ public void ToUriComponentEscapeCorrectly(string category, string input, string
  }
 
  [Fact]
- public void PathStringConvertsFromString()
+ public void PathStringConvertsOnlyToAndFromString()
  {
  var converter = TypeDescriptor.GetConverter(typeof(PathString));
  PathString result = (PathString)converter.ConvertFromInvariantString("/foo");
  Assert.Equal("/foo", result.ToString());
+ Assert.Equal("/foo", converter.ConvertTo(result, typeof(string)));
+ Assert.True(converter.CanConvertFrom(typeof(string)));
+ Assert.False(converter.CanConvertFrom(typeof(int)));
+ Assert.False(converter.CanConvertFrom(typeof(bool)));
+ Assert.True(converter.CanConvertTo(typeof(string)));
+ Assert.False(converter.CanConvertTo(typeof(int)));
+ Assert.False(converter.CanConvertTo(typeof(bool)));
+ }
+
+ [Fact]
+ public void PathStringStaysEqualAfterAssignments()
+ {
+ PathString p1 = "/?";
+ string s1 = p1;
+ PathString p2 = s1;
+ Assert.Equal(p1, p2);
  }
  }
 }