Add more code coverage requested in review

#2044 (comment)

Author: baynezy

Refit.Tests/RequestBuilder.cs

@@ -1773,6 +1773,12 @@ Task<string> FetchSomeStuffWithHardcodedAndOtherQueryParameters(
         [Get("/foo?q=app_metadata.id:\"{id}\"")]
         Task<string> FetchSomeStuffWithDoubleQuotesInUrl(int id);
 
+        [Get("/foo/bar/({id})")]
+        Task<string> GetWithTrainingParenthesis(int id);
+
+        [Get("/foo/bar/{id}/")]
+        Task<string> GetWithTrailingSlash(int id);
+
         [Post("/foo/bar/{id}")]
         [Headers("Content-Type: literally/anything")]
         Task<string> PostSomeStuffWithHardCodedContentTypeHeader(int id, [Body] string content);
@@ -2604,13 +2610,30 @@ public void QueryParamWhichEndsInDoubleQuotesShouldNotBeTruncated()
             var factory = fixture.BuildRequestFactoryForMethod(
                 "FetchSomeStuffWithDoubleQuotesInUrl"
             );
-            var output = factory(new object[] { 42 });
+            var output = factory([42]);
 
-            var uri = new Uri(new Uri("http://api"), output.RequestUri);
+            var uri = new Uri(new Uri("http://api"), output.RequestUri!);
 
             Assert.Equal("/foo?q=app_metadata.id%3A%2242%22", uri.PathAndQuery);
         }
 
+        [Theory]
+        [InlineData("GetWithTrainingParenthesis", ")", "/foo/bar/(1)")]
+        [InlineData("GetWithTrailingSlash", "/", "/foo/bar/1/")]
+        public void ShouldCaptureLastCharacterWhenRouteEndsWithConstant(string methodToTest, string constantChar, string contains)
+        {
+            var fixture = new RequestBuilderImplementation<IDummyHttpApi>();
+            var factory = fixture.BuildRequestFactoryForMethod(
+                methodToTest
+            );
+            var output = factory(["1"]);
+
+            var uri = new Uri(new Uri("http://api/"), output.RequestUri!);
+
+            Assert.EndsWith(constantChar, uri.PathAndQuery, StringComparison.Ordinal);
+            Assert.Contains(contains, uri.PathAndQuery, StringComparison.Ordinal);
+        }
+
         [Fact]
         public void ParameterizedQueryParamsShouldBeInUrlAndValuesEncodedWhenMixedReplacementAndQueryBadId()
         {

Refit/RestMethodInfo.cs

@@ -401,12 +401,12 @@ ParameterInfo[] parameterInfo
                 }
             }
 
+            if (index >= relativePath.Length) return (ret, fragmentList);
+
             // add trailing string
-            if (index < relativePath.Length)
-            {
-                var trailingConstant = relativePath.Substring(index, relativePath.Length - index);
-                fragmentList.Add(ParameterFragment.Constant(trailingConstant));
-            }
+            var trailingConstant = relativePath.Substring(index);
+            fragmentList.Add(ParameterFragment.Constant(trailingConstant));
+
             return (ret, fragmentList);
         }