Update QueryStringParser to support param with equal but no value

src/WireMock.Net/Matchers/Request/RequestMessageParamMatcher.cs

@@ -142,6 +142,6 @@ private static double CalculateScore(IReadOnlyList<IStringMatcher> matchers, Wir
             }
         }
 
-        return total.Any() ? MatchScores.ToScore(total, MatchOperator.Average) : default;
+        return total.Any() ? MatchScores.ToScore(total, MatchOperator.Average) : 0;
     }
 }

src/WireMock.Net/Util/QueryStringParser.cs

@@ -20,12 +20,12 @@ public static bool TryParse(string? queryString, bool caseIgnore, [NotNullWhen(t
     {
         if (queryString is null)
         {
-            nameValueCollection = default;
+            nameValueCollection = null;
             return false;
         }
 
         var parts = queryString!
-            .Split(new[] { "&" }, StringSplitOptions.RemoveEmptyEntries)
+            .Split(["&"], StringSplitOptions.RemoveEmptyEntries)
             .Select(parameter => parameter.Split('='))
             .Distinct();
 
@@ -50,18 +50,6 @@ public static IDictionary<string, WireMockList<string>> Parse(string? queryStrin
 
         var queryParameterMultipleValueSupport = support ?? QueryParameterMultipleValueSupport.All;
 
-        string[] JoinParts(string[] parts)
-        {
-            if (parts.Length > 1)
-            {
-                return queryParameterMultipleValueSupport.HasFlag(QueryParameterMultipleValueSupport.Comma) ?
-                    parts[1].Split(new[] { "," }, StringSplitOptions.RemoveEmptyEntries) : // Support "?key=1,2"
-                    new[] { parts[1] };
-            }
-
-            return new string[0];
-        }
-
         var splitOn = new List<string>();
         if (queryParameterMultipleValueSupport.HasFlag(QueryParameterMultipleValueSupport.Ampersand))
         {
@@ -74,8 +62,24 @@ string[] JoinParts(string[] parts)
 
         return queryString!.TrimStart('?')
             .Split(splitOn.ToArray(), StringSplitOptions.RemoveEmptyEntries)
-            .Select(parameter => parameter.Split(new[] { '=' }, 2, StringSplitOptions.RemoveEmptyEntries))
-            .GroupBy(parts => parts[0], JoinParts)
-            .ToDictionary(grouping => grouping.Key, grouping => new WireMockList<string>(grouping.SelectMany(x => x).Select(WebUtility.UrlDecode)));
+            .Select(parameter => new { hasEqualSign = parameter.Contains('='), parts = parameter.Split(['='], 2, StringSplitOptions.RemoveEmptyEntries) })
+            .GroupBy(x => x.parts[0], y => JoinParts(y.hasEqualSign, y.parts))
+            .ToDictionary
+            (
+                grouping => grouping.Key,
+                grouping => new WireMockList<string>(grouping.SelectMany(x => x).Select(WebUtility.UrlDecode).OfType<string>())
+            );
+
+        string[] JoinParts(bool hasEqualSign, string[] parts)
+        {
+            if (parts.Length > 1)
+            {
+                return queryParameterMultipleValueSupport.HasFlag(QueryParameterMultipleValueSupport.Comma) ?
+                    parts[1].Split([","], StringSplitOptions.RemoveEmptyEntries) : // Support "?key=1,2"
+                    [parts[1]];
+            }
+
+            return hasEqualSign ? [string.Empty] : []; // Return empty string if equal sign with no value (#1247)
+        }
     }
 }

test/WireMock.Net.Tests/RequestMatchers/RequestMessageParamMatcherTests.cs

@@ -43,6 +43,21 @@ public void RequestMessageParamMatcher_GetMatchingScore_KeyWith1ValuePresentInUr
         Check.That(score).IsEqualTo(0.5d);
     }
 
+    [Fact]
+    public void RequestMessageParamMatcher_GetMatchingScore_KeyWithNoValuePresentInUrl_Returns1_0()
+    {
+        // Assign
+        var requestMessage = new RequestMessage(new UrlDetails("http://localhost?key="), "GET", "127.0.0.1");
+        var matcher = new RequestMessageParamMatcher(MatchBehaviour.AcceptOnMatch, "key", false, "");
+
+        // Act
+        var result = new RequestMatchResult();
+        var score = matcher.GetMatchingScore(requestMessage, result);
+
+        // Assert
+        Check.That(score).IsEqualTo(1.0d);
+    }
+
     [Fact]
     public void RequestMessageParamMatcher_GetMatchingScore_KeyWith3ValuesPresentInUrl_And_With1ExactStringWith2Patterns_Returns0_66()
     {

test/WireMock.Net.Tests/Util/QueryStringParserTests.cs

@@ -148,7 +148,7 @@ public void Parse_With1ParamNoValueWithEqualSign()
 
         // Assert
         result.Count.Should().Be(1);
-        result["empty"].Should().Equal(new WireMockList<string>());
+        result["empty"].Should().Equal(new WireMockList<string>(""));
     }
 
     [Fact]
@@ -354,18 +354,19 @@ public void Parse_With1ParamContainingComma_Using_QueryParameterMultipleValueSup
     public void Parse_WithComplex()
     {
         // Assign
-        string query = "?q=energy+edge&rls=com.microsoft:en-au&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1%22";
+        string query = "?q=energy+edge&rls=com.microsoft:en-au&ie=UTF-8&oe=UTF-8&startIndex=&startPage=1%22&x";
 
         // Act
         var result = QueryStringParser.Parse(query);
 
         // Assert
-        result.Count.Should().Be(6);
+        result.Count.Should().Be(7);
         result["q"].Should().Equal(new WireMockList<string>("energy edge"));
         result["rls"].Should().Equal(new WireMockList<string>("com.microsoft:en-au"));
         result["ie"].Should().Equal(new WireMockList<string>("UTF-8"));
         result["oe"].Should().Equal(new WireMockList<string>("UTF-8"));
-        result["startIndex"].Should().Equal(new WireMockList<string>());
+        result["startIndex"].Should().Equal(new WireMockList<string>(""));
         result["startPage"].Should().Equal(new WireMockList<string>("1\""));
+        result["x"].Should().Equal(new WireMockList<string>());
     }
 }