Fix non-greedy request header matching

HttpClientInterception.slnx

@@ -0,0 +1,60 @@
+<Solution>
+  <Folder Name="/samples/">
+    <File Path="samples/README.md" />
+    <Project Path="samples/SampleApp.Tests/SampleApp.Tests.csproj" />
+    <Project Path="samples/SampleApp/SampleApp.csproj" />
+  </Folder>
+  <Folder Name="/Solution Items/">
+    <File Path=".editorconfig" />
+    <File Path=".gitattributes" />
+    <File Path=".gitignore" />
+    <File Path=".vsconfig" />
+    <File Path="build.ps1" />
+    <File Path="Directory.Build.props" />
+    <File Path="Directory.Build.targets" />
+    <File Path="Directory.Packages.props" />
+    <File Path="global.json" />
+    <File Path="HttpClientInterception.ruleset" />
+    <File Path="LICENSE" />
+    <File Path="NuGet.config" />
+    <File Path="README.md" />
+    <File Path="SECURITY.md" />
+    <File Path="stylecop.json" />
+  </Folder>
+  <Folder Name="/Solution Items/.github/">
+    <File Path=".github/CODEOWNERS" />
+    <File Path=".github/CONTRIBUTING.md" />
+    <File Path=".github/dependabot.yml" />
+    <File Path=".github/ISSUE_TEMPLATE.md" />
+    <File Path=".github/PULL_REQUEST_TEMPLATE.md" />
+    <File Path=".github/stale.yml" />
+  </Folder>
+  <Folder Name="/Solution Items/.github/ISSUE_TEMPLATE/">
+    <File Path=".github/ISSUE_TEMPLATE/bug_report.md" />
+    <File Path=".github/ISSUE_TEMPLATE/feature_request.md" />
+  </Folder>
+  <Folder Name="/Solution Items/.github/workflows/">
+    <File Path=".github/workflows/approve-and-merge.yml" />
+    <File Path=".github/workflows/build.yml" />
+    <File Path=".github/workflows/bump-version.yml" />
+    <File Path=".github/workflows/codeql.yml" />
+    <File Path=".github/workflows/dependabot-approve.yml" />
+    <File Path=".github/workflows/dependency-review.yml" />
+    <File Path=".github/workflows/lint.yml" />
+    <File Path=".github/workflows/release.yml" />
+    <File Path=".github/workflows/scorecard.yml" />
+    <File Path=".github/workflows/update-docs.yml" />
+    <File Path=".github/workflows/update-dotnet-sdk.yml" />
+  </Folder>
+  <Folder Name="/Solution Items/.vscode/">
+    <File Path=".vscode/launch.json" />
+    <File Path=".vscode/tasks.json" />
+  </Folder>
+  <Folder Name="/src/">
+    <Project Path="src/HttpClientInterception/JustEat.HttpClientInterception.csproj" />
+  </Folder>
+  <Folder Name="/tests/">
+    <Project Path="tests/HttpClientInterception.Benchmarks/JustEat.HttpClientInterception.Benchmarks.csproj" />
+    <Project Path="tests/HttpClientInterception.Tests/JustEat.HttpClientInterception.Tests.csproj" />
+  </Folder>
+</Solution>

src/HttpClientInterception/HttpClientInterceptorOptions.cs

@@ -575,7 +575,17 @@ private static async Task<HttpResponseMessage> BuildResponseAsync(HttpRequestMes
     {
         var responses = _mappings.Values
             .OrderByDescending((p) => p.Priority.HasValue)
-            .ThenBy((p) => p.Priority);
+            .ThenBy((p) => p.Priority)
+            .ThenByDescending((p) =>
+            {
+                // Sort by the number of request headers, so that those with more headers expected are matched first.
+                // Count() is not used to avoid side-effects of enumerating the headers if they are dynamically generated.
+#if NET8_0_OR_GREATER
+                return p.RequestHeaders?.TryGetNonEnumeratedCount(out var count) is true ? count : 0;
+#else
+                return p.RequestHeaders is ICollection<KeyValuePair<string, IEnumerable<string>>> collection ? collection.Count : 0;
+#endif
+            });
 
         foreach (var response in responses)
         {

tests/HttpClientInterception.Tests/Bundles/BundleExtensionsTests.cs

@@ -601,4 +601,34 @@ public static void Can_Register_Bundle_With_Null_Header_Values_In_Bundle()
         // Act
         options.RegisterBundle(Path.Join("Bundles", "templated-bundle-null-headers.json"), headers);
     }
+
+    [Fact]
+    public static async Task Can_Intercept_Http_Requests_With_Correct_Precedence_For_Http_Request_Headers()
+    {
+        // Arrange
+        var options = new HttpClientInterceptorOptions().ThrowsOnMissingRegistration();
+
+        var requestUrl = "https://registry.hub.docker.com/v2/user/image/manifests/latest";
+
+        var unauthorized = new Dictionary<string, string>()
+        {
+            ["Accept"] = "application/vnd.oci.image.index.v1+json",
+        };
+
+        var authorized = new Dictionary<string, string>()
+        {
+            ["Accept"] = "application/vnd.oci.image.index.v1+json",
+            ["Authorization"] = "Bearer not-a-real-docker-hub-token",
+        };
+
+        options.RegisterBundle(Path.Join("Bundles", "header-matching.json"));
+
+        // Act
+        var first = await HttpAssert.GetAsync(options, requestUrl, headers: unauthorized);
+        var second = await HttpAssert.GetAsync(options, requestUrl, headers: authorized);
+
+        // Assert
+        first.ShouldBe("unauthorized");
+        second.ShouldBe("authorized");
+    }
 }

tests/HttpClientInterception.Tests/Bundles/header-matching.json

@@ -0,0 +1,36 @@
+{
+  "$schema": "https://raw.githubusercontent.com/justeattakeaway/httpclient-interception/main/src/HttpClientInterception/Bundles/http-request-bundle-schema.json",
+  "id": "test-http-request-bundle",
+  "comment": "An HTTP request bundle for testing HTTP request header matching for the same URL.",
+  "version": 1,
+  "items": [
+    {
+      "id": "authorized",
+      "comment": "An HTTP request with an Authorization header.",
+      "uri": "https://registry.hub.docker.com/v2/user/image/manifests/latest",
+      "requestHeaders": {
+        "Accept": [
+          "application/vnd.oci.image.index.v1+json"
+        ],
+        "Authorization": [
+          "Bearer not-a-real-docker-hub-token"
+        ]
+      },
+      "contentString": "authorized"
+    },
+    {
+      "id": "unauthorized",
+      "comment": "An HTTP request without an Authorization header.",
+      "uri": "https://registry.hub.docker.com/v2/user/image/manifests/latest",
+      "requestHeaders": {
+        "Accept": [
+          "application/vnd.oci.image.index.v1+json"
+        ]
+      },
+      "contentHeaders": {
+        "Content-Type": [ "application/json" ]
+      },
+      "contentString": "unauthorized"
+    }
+  ]
+}