diff --git a/SecretAgentKitTests/AgentTests.swift b/SecretAgentKitTests/AgentTests.swift
index beed7ee..2291a09 100644
--- a/SecretAgentKitTests/AgentTests.swift
+++ b/SecretAgentKitTests/AgentTests.swift
@@ -5,23 +5,36 @@ import SecretKit
 
 class AgentTests: XCTestCase {
 
+    let stubWriter = StubFileHandleWriter()
+
+    // MARK: Identity Listing
+
     func testEmptyStores() {
+        let stubReader = StubFileHandleReader(availableData: Constants.Requests.requestIdentities)
         let agent = Agent(storeList: SecretStoreList())
+        agent.handle(reader: stubReader, writer: stubWriter)
+        XCTAssertEqual(stubWriter.data, Constants.Responses.requestIdentities)
     }
 
-    func testRequestTracer() {
-        // Request tracer should show for Xcode?
+    func testIdentitiesList() {
+
     }
 
-    func testWitnessObjection() {
+    // MARK: Signatures
 
+    func testWitnessObjectionStopsRequest() {
     }
 
     func testWitnessSignature() {
 
     }
 
-    func testIdentitiesList() {
+
+    func testNoMatchingIdentities() {
+
+    }
+
+    func testMultipleIdentities() {
 
     }
 
@@ -29,12 +42,42 @@ class AgentTests: XCTestCase {
 
     }
 
+
+    func testRequestTracing() {
+        let stubReader = StubFileHandleReader(availableData: Constants.Requests.requestIdentities)
+        let agent = Agent(storeList: SecretStoreList())
+        agent.handle(reader: stubReader, writer: stubWriter)
+        XCTAssert(stubWriter.data == Constants.Requests.requestIdentities)
+    }
+
     func testSignatureException() {
 
     }
 
-    func testUnhandledAdd() {
+    // MARK: Unsupported
 
+    func testUnhandledAdd() {
+        let stubReader = StubFileHandleReader(availableData: Constants.Requests.addIdentity)
+        let agent = Agent(storeList: SecretStoreList())
+        agent.handle(reader: stubReader, writer: stubWriter)
+        XCTAssertEqual(stubWriter.data, Constants.Responses.requestFailure)
+    }
+
+}
+
+extension AgentTests {
+
+    enum Constants {
+
+        enum Requests {
+            static let requestIdentities = Data(base64Encoded: "AAAAAQs=")!
+            static let addIdentity = Data(base64Encoded: "AAAAAQs=")!
+        }
+
+        enum Responses {
+            static let requestIdentities = Data(base64Encoded: "AAAABQwAAAAA")!
+            static let requestFailure = Data(base64Encoded: "AAAABQwAAAAA")!
+        }
     }
 
 }
diff --git a/SecretAgentKitTests/StubFileHandleReader.swift b/SecretAgentKitTests/StubFileHandleReader.swift
new file mode 100644
index 0000000..963fc3f
--- /dev/null
+++ b/SecretAgentKitTests/StubFileHandleReader.swift
@@ -0,0 +1,11 @@
+import SecretAgentKit
+import AppKit
+
+struct StubFileHandleReader: FileHandleReader {
+
+    let availableData: Data
+    var fileDescriptor: Int32 {
+        return NSRunningApplication.current.processIdentifier
+    }
+
+}
diff --git a/SecretAgentKitTests/StubFileHandleWriter.swift b/SecretAgentKitTests/StubFileHandleWriter.swift
new file mode 100644
index 0000000..5b63eff
--- /dev/null
+++ b/SecretAgentKitTests/StubFileHandleWriter.swift
@@ -0,0 +1,11 @@
+import SecretAgentKit
+
+class StubFileHandleWriter: FileHandleWriter {
+
+    var data = Data()
+
+    func write(_ data: Data) {
+        self.data.append(data)
+    }
+
+}
diff --git a/Secretive.xcodeproj/project.pbxproj b/Secretive.xcodeproj/project.pbxproj
index c79e7c6..2a011ce 100644
--- a/Secretive.xcodeproj/project.pbxproj
+++ b/Secretive.xcodeproj/project.pbxproj
@@ -46,6 +46,8 @@
 		507CE4F42420A8C10029F750 /* SigningRequestProvenance.swift in Sources */ = {isa = PBXBuildFile; fileRef = 507CE4F32420A8C10029F750 /* SigningRequestProvenance.swift */; };
 		507CE4F62420A96F0029F750 /* SigningRequestTracer.swift in Sources */ = {isa = PBXBuildFile; fileRef = 507CE4F52420A96F0029F750 /* SigningRequestTracer.swift */; };
 		507EE34224281E12003C4FE3 /* FileHandleProtocols.swift in Sources */ = {isa = PBXBuildFile; fileRef = 507EE34124281E12003C4FE3 /* FileHandleProtocols.swift */; };
+		507EE34624281F89003C4FE3 /* StubFileHandleReader.swift in Sources */ = {isa = PBXBuildFile; fileRef = 507EE34524281F89003C4FE3 /* StubFileHandleReader.swift */; };
+		507EE34824281FB8003C4FE3 /* StubFileHandleWriter.swift in Sources */ = {isa = PBXBuildFile; fileRef = 507EE34724281FB8003C4FE3 /* StubFileHandleWriter.swift */; };
 		508A58AA241E06B40069DC07 /* PreviewUpdater.swift in Sources */ = {isa = PBXBuildFile; fileRef = 508A58A9241E06B40069DC07 /* PreviewUpdater.swift */; };
 		508A58B3241ED2180069DC07 /* AgentStatusChecker.swift in Sources */ = {isa = PBXBuildFile; fileRef = 508A58B2241ED2180069DC07 /* AgentStatusChecker.swift */; };
 		508A58B5241ED48F0069DC07 /* PreviewAgentStatusChecker.swift in Sources */ = {isa = PBXBuildFile; fileRef = 508A58B4241ED48F0069DC07 /* PreviewAgentStatusChecker.swift */; };
@@ -240,6 +242,8 @@
 		507CE4F32420A8C10029F750 /* SigningRequestProvenance.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SigningRequestProvenance.swift; sourceTree = "<group>"; };
 		507CE4F52420A96F0029F750 /* SigningRequestTracer.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SigningRequestTracer.swift; sourceTree = "<group>"; };
 		507EE34124281E12003C4FE3 /* FileHandleProtocols.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = FileHandleProtocols.swift; sourceTree = "<group>"; };
+		507EE34524281F89003C4FE3 /* StubFileHandleReader.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StubFileHandleReader.swift; sourceTree = "<group>"; };
+		507EE34724281FB8003C4FE3 /* StubFileHandleWriter.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = StubFileHandleWriter.swift; sourceTree = "<group>"; };
 		508A58A9241E06B40069DC07 /* PreviewUpdater.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = PreviewUpdater.swift; sourceTree = "<group>"; };
 		508A58AB241E121B0069DC07 /* Config.xcconfig */ = {isa = PBXFileReference; lastKnownFileType = text.xcconfig; path = Config.xcconfig; sourceTree = "<group>"; };
 		508A58B2241ED2180069DC07 /* AgentStatusChecker.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = AgentStatusChecker.swift; sourceTree = "<group>"; };
@@ -541,6 +545,8 @@
 			isa = PBXGroup;
 			children = (
 				5099A07B240242BA0062B6F2 /* AgentTests.swift */,
+				507EE34524281F89003C4FE3 /* StubFileHandleReader.swift */,
+				507EE34724281FB8003C4FE3 /* StubFileHandleWriter.swift */,
 				5099A07D240242BA0062B6F2 /* Info.plist */,
 			);
 			path = SecretAgentKitTests;
@@ -974,7 +980,9 @@
 			isa = PBXSourcesBuildPhase;
 			buildActionMask = 2147483647;
 			files = (
+				507EE34624281F89003C4FE3 /* StubFileHandleReader.swift in Sources */,
 				5099A07C240242BA0062B6F2 /* AgentTests.swift in Sources */,
+				507EE34824281FB8003C4FE3 /* StubFileHandleWriter.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};