ASP009 Use lowercase urls. Close #13.

Only fixing single word segments. Multiword needs strategy for lower casing like snake_case or kebab-case.

Author: JohanLarsson

AspNetCoreAnalyzers.Tests/ASP009LowercaseUrlsTests/CodeFix.cs

@@ -0,0 +1,50 @@
+namespace AspNetCoreAnalyzers.Tests.ASP009LowercaseUrlsTests
+{
+    using Gu.Roslyn.Asserts;
+    using Microsoft.CodeAnalysis.CodeFixes;
+    using Microsoft.CodeAnalysis.Diagnostics;
+    using NUnit.Framework;
+
+    public class CodeFix
+    {
+        private static readonly DiagnosticAnalyzer Analyzer = new AttributeAnalyzer();
+        private static readonly ExpectedDiagnostic ExpectedDiagnostic = ExpectedDiagnostic.Create(ASP009LowercaseUrl.Descriptor);
+        private static readonly CodeFixProvider Fix = new TemplateTextFix();
+
+        [TestCase("\"api/↓Orders/{id}\"", "\"api/orders/{id}\"")]
+        public void WhenMethodAttribute(string before, string after)
+        {
+            var code = @"
+namespace ValidCode
+{
+    using Microsoft.AspNetCore.Mvc;
+
+    [ApiController]
+    public class OrdersController : Controller
+    {
+        [HttpGet(""api/Orders/{id}"")]
+        public IActionResult GetId(string id)
+        {
+            return this.Ok(id);
+        }
+    }
+}".AssertReplace("\"api/Orders/{id}\"", before);
+
+            var fixedCode = @"
+namespace ValidCode
+{
+    using Microsoft.AspNetCore.Mvc;
+
+    [ApiController]
+    public class OrdersController : Controller
+    {
+        [HttpGet(""api/orders/{id}"")]
+        public IActionResult GetId(string id)
+        {
+            return this.Ok(id);
+        }
+    }
+}".AssertReplace("\"api/orders/{id}\"", after);
+            AnalyzerAssert.CodeFix(Analyzer, Fix, ExpectedDiagnostic, code, fixedCode);
+        }
+}

AspNetCoreAnalyzers.Tests/ASP009LowercaseUrlsTests/ValidCode.cs

@@ -0,0 +1,36 @@
+namespace AspNetCoreAnalyzers.Tests.ASP009LowercaseUrlsTests
+{
+    using Gu.Roslyn.Asserts;
+    using Microsoft.CodeAnalysis.Diagnostics;
+    using NUnit.Framework;
+
+    public class ValidCode
+    {
+        private static readonly DiagnosticAnalyzer Analyzer = new AttributeAnalyzer();
+
+        [TestCase("\"{value}\"")]
+        [TestCase("\"api/orders/{value}\"")]
+        [TestCase("\"api/TwoWords/{value}\"")]
+        public void WithParameter(string parameter)
+        {
+            var code = @"
+namespace ValidCode
+{
+    using System.Threading.Tasks;
+    using Microsoft.AspNetCore.Mvc;
+    using Microsoft.EntityFrameworkCore;
+
+    [ApiController]
+    public class OrdersController : Controller
+    {
+        [HttpGet(""api/{value}"")]
+        public IActionResult GetValue(string value)
+        {
+            return this.Ok(value);
+        }
+    }
+}".AssertReplace("\"api/{value}\"", parameter);
+            AnalyzerAssert.Valid(Analyzer, code);
+        }
+    }
+}

AspNetCoreAnalyzers.sln

@@ -36,6 +36,7 @@ Project("{2150E333-8FDC-42A3-9474-1A3956D46DE8}") = ".docs", ".docs", "{1C271AF2
 		documentation\ASP005.md = documentation\ASP005.md
 		documentation\ASP006.md = documentation\ASP006.md
 		documentation\ASP008.md = documentation\ASP008.md
+		documentation\ASP009.md = documentation\ASP009.md
 		README.md = README.md
 		RELEASE_NOTES.md = RELEASE_NOTES.md
 	EndProjectSection

AspNetCoreAnalyzers/ASP009LowercaseUrl.cs

@@ -0,0 +1,19 @@
+namespace AspNetCoreAnalyzers
+{
+    using Microsoft.CodeAnalysis;
+
+    internal static class ASP009LowercaseUrl
+    {
+        public const string DiagnosticId = "ASP009";
+
+        internal static readonly DiagnosticDescriptor Descriptor = new DiagnosticDescriptor(
+            id: DiagnosticId,
+            title: "Use lowercase urls.",
+            messageFormat: "Use lowercase urls.",
+            category: AnalyzerCategory.Routing,
+            defaultSeverity: DiagnosticSeverity.Warning,
+            isEnabledByDefault: true,
+            description: "Use lowercase urls.",
+            helpLinkUri: HelpLink.ForId(DiagnosticId));
+    }
+}

AspNetCoreAnalyzers/Analyzers/AttributeAnalyzer.cs

@@ -22,7 +22,8 @@ public class AttributeAnalyzer : DiagnosticAnalyzer
             ASP005ParameterSyntax.Descriptor,
             ASP006ParameterRegex.Descriptor,
             ASP007MissingParameter.Descriptor,
-            ASP008ValidRouteParameterName.Descriptor);
+            ASP008ValidRouteParameterName.Descriptor,
+            ASP009LowercaseUrl.Descriptor);
 
         public override void Initialize(AnalysisContext context)
         {
@@ -133,6 +134,17 @@ context.ContainingSymbol is IMethodSymbol method &&
                                         ? ImmutableDictionary<string, string>.Empty
                                         : ImmutableDictionary<string, string>.Empty.Add(nameof(Text), name)));
                         }
+
+                        if (IsUpperCase(segment, out var lowercase))
+                        {
+                            context.ReportDiagnostic(
+                                Diagnostic.Create(
+                                    ASP009LowercaseUrl.Descriptor,
+                                    segment.Span.GetLocation(),
+                                    lowercase == null
+                                        ? ImmutableDictionary<string, string>.Empty
+                                        : ImmutableDictionary<string, string>.Empty.Add(nameof(Text), lowercase)));
+                        }
                     }
                 }
             }
@@ -501,7 +513,8 @@ private static bool HasInvalidName(PathSegment segment, out Location location, o
                     parameter.Name.EndsWith(" ", StringComparison.OrdinalIgnoreCase))
                 {
                     location = parameter.Name.GetLocation();
-                    correctName = parameter.Name.ToString().Trim();
+                    correctName = parameter.Name.ToString()
+                                           .Trim();
                     return true;
                 }
 
@@ -521,5 +534,28 @@ private static bool HasInvalidName(PathSegment segment, out Location location, o
             correctName = null;
             return false;
         }
+
+        private static bool IsUpperCase(PathSegment segment, out string lowercase)
+        {
+            if (segment.Parameter == null &&
+                segment.Span.Length > 0 &&
+                char.IsUpper(segment.Span[0]))
+            {
+                for (var i = 1; i < segment.Span.Length; i++)
+                {
+                    if (char.IsUpper(segment.Span[i]))
+                    {
+                        lowercase = null;
+                        return false;
+                    }
+                }
+
+                lowercase = segment.Span.ToString().ToLower();
+                return true;
+            }
+
+            lowercase = null;
+            return false;
+        }
     }
 }

AspNetCoreAnalyzers/CodeFixes/TemplateTextFix.cs

@@ -20,7 +20,8 @@ public class TemplateTextFix : CodeFixProvider
             ASP004RouteParameterType.DiagnosticId,
             ASP005ParameterSyntax.DiagnosticId,
             ASP006ParameterRegex.DiagnosticId,
-            ASP008ValidRouteParameterName.DiagnosticId);
+            ASP008ValidRouteParameterName.DiagnosticId,
+            ASP009LowercaseUrl.DiagnosticId);
 
         public override FixAllProvider GetFixAllProvider() => null;
 
@@ -65,6 +66,8 @@ private static string GetTitle(Diagnostic diagnostic)
                     return "Escape regex.";
                 case ASP008ValidRouteParameterName.DiagnosticId:
                     return "Fix name.";
+                case ASP009LowercaseUrl.DiagnosticId:
+                    return "To lowercase.";
                 default:
                     throw new InvalidOperationException("Should never get here.");
             }

README.md

@@ -43,6 +43,10 @@ Roslyn analyzers for ASP.NET.Core.
     <td><a href="https://github.com/DotNetAnalyzers/AspNetCoreAnalyzers/tree/master/documentation/ASP008.md">ASP008</a></td>
     <td>Invalid route parameter name.</td>
   </tr>
+  <tr>
+    <td><a href="https://github.com/DotNetAnalyzers/AspNetCoreAnalyzers/tree/master/documentation/ASP009.md">ASP009</a></td>
+    <td>Use lowercase urls.</td>
+  </tr>
 <table>
 <!-- end generated table -->
 

documentation/ASP009.md

@@ -0,0 +1,67 @@
+# ASP009
+## Use lowercase urls.
+
+<!-- start generated table -->
+<table>
+  <tr>
+    <td>CheckId</td>
+    <td>ASP009</td>
+  </tr>
+  <tr>
+    <td>Severity</td>
+    <td>Warning</td>
+  </tr>
+  <tr>
+    <td>Enabled</td>
+    <td>True</td>
+  </tr>
+  <tr>
+    <td>Category</td>
+    <td>AspNetCoreAnalyzers.Routing</td>
+  </tr>
+  <tr>
+    <td>Code</td>
+    <td><a href="https://github.com/DotNetAnalyzers/AspNetCoreAnalyzers/blob/master/AspNetCoreAnalyzers/Analyzers/AttributeAnalyzer.cs">AttributeAnalyzer</a></td>
+  </tr>
+</table>
+<!-- end generated table -->
+
+## Description
+
+Use lowercase urls.
+
+## Motivation
+
+ADD MOTIVATION HERE
+
+## How to fix violations
+
+ADD HOW TO FIX VIOLATIONS HERE
+
+<!-- start generated config severity -->
+## Configure severity
+
+### Via ruleset file.
+
+Configure the severity per project, for more info see [MSDN](https://msdn.microsoft.com/en-us/library/dd264949.aspx).
+
+### Via #pragma directive.
+```C#
+#pragma warning disable ASP009 // Use lowercase urls.
+Code violating the rule here
+#pragma warning restore ASP009 // Use lowercase urls.
+```
+
+Or put this at the top of the file to disable all instances.
+```C#
+#pragma warning disable ASP009 // Use lowercase urls.
+```
+
+### Via attribute `[SuppressMessage]`.
+
+```C#
+[System.Diagnostics.CodeAnalysis.SuppressMessage("AspNetCoreAnalyzers.Routing", 
+    "ASP009:Use lowercase urls.", 
+    Justification = "Reason...")]
+```
+<!-- end generated config severity -->