diff --git a/Sources/Macros/Macros.swift b/Sources/Macros/Macros.swift
index c85a7d5..ea6b5d0 100644
--- a/Sources/Macros/Macros.swift
+++ b/Sources/Macros/Macros.swift
@@ -301,43 +301,47 @@ public struct CliTestDeclarationMacro: PeerMacro, Sendable {
     in context: some MacroExpansionContext
   ) throws -> [DeclSyntax] {
 
+    let test_name = declaration.cast(FunctionDeclSyntax.self).name
+
     let cli_test_expected_output = node.leadingTrivia.filter({ $0.isComment }).map({
       doc_shrink("\($0)")
     }).joined(separator: "\\n")
 
     let cli_test_driver_thunk_name = context.makeUniqueName(
       declaration.cast(FunctionDeclSyntax.self).name.text + "_thunk_")
+
+    let (expected_decl, expected_label) = if cli_test_expected_output.isEmpty {
+      ("let expected = \"\(test_name)\"", "withExpectedPath:")
+    } else {
+      ("let expected = \"\(cli_test_expected_output)\"", "withExpected:")
+    }
+
     let cli_test_driver_thunk: DeclSyntax = """
       @Sendable private func \(cli_test_driver_thunk_name)() async throws {
-        let expected = "\(raw: cli_test_expected_output)"
+        \(raw: expected_decl)
 
         _ = unsafe try await Testing.__requiringUnsafe(
           Testing.__requiringTry(
-            Testing.__requiringAwait(swiftCliTestRunner(\(declaration.cast(FunctionDeclSyntax.self).name), expected))))
+            Testing.__requiringAwait(swiftCliTestRunner(\(test_name), \(raw: expected_label) expected))))
       }
       """
 
-    let cli_test_driver_generator_name = context.makeUniqueName(
-      declaration.cast(FunctionDeclSyntax.self).name.text + "_generator_")
+    let cli_test_driver_generator_name = context.makeUniqueName(test_name.text + "_generator_")
     let cli_test_driver_generator: DeclSyntax = """
         @Sendable private func \(cli_test_driver_generator_name)() async -> Testing.Test {
           return .__function(
-            named: "xxxxxxxx()",
+            named: "\(test_name)",
             in: nil,
-            xcTestCompatibleSelector: Testing.__xcTestCompatibleSelector("xxxxxx:"),
+            xcTestCompatibleSelector: Testing.__xcTestCompatibleSelector("\(test_name)"),
             traits: [],
-            sourceLocation: Testing.SourceLocation(
-              fileID: "Tests/CliTests/Cli.swift",
-              filePath: "/Users/hawkinsw/code/p4ce/Tests/p4rseTests/CliTests/Cli.swift", line: 359,
-              column: 2),
+            sourceLocation: Testing.SourceLocation.__here(),
             parameters: [],
             testFunction: \(cli_test_driver_thunk_name)
           )
         }
       """
 
-    let cli_test_driver_accessor_name = context.makeUniqueName(
-      declaration.cast(FunctionDeclSyntax.self).name.text + "_accessor_")
+    let cli_test_driver_accessor_name = context.makeUniqueName(test_name.text + "_accessor_")
     let cli_test_driver_accessor: DeclSyntax = """
         private nonisolated let \(cli_test_driver_accessor_name): Accessor = { outValue, type, _, _ in
 
@@ -357,8 +361,7 @@ public struct CliTestDeclarationMacro: PeerMacro, Sendable {
         )
       """
 
-    let cli_test_driver_content_container_name = context.makeUniqueName(
-      declaration.cast(FunctionDeclSyntax.self).name.text + "__🟡$_container_")
+    let cli_test_driver_content_container_name = context.makeUniqueName(test_name.text + "__🟡$_container_")
     let cli_test_driver_container: DeclSyntax = """
         struct \(cli_test_driver_content_container_name): Testing.__TestContentRecordContainer {
           nonisolated static var __testContentRecord: TestContentRecord {
diff --git a/TestData/simple_cli_preprocessor_test.golden b/TestData/simple_cli_preprocessor_test.golden
new file mode 100644
index 0000000..b5a1837
--- /dev/null
+++ b/TestData/simple_cli_preprocessor_test.golden
@@ -0,0 +1,8 @@
+    parser main_parser() {
+       state start {
+           transition select (false) {
+              true: reject;
+              false: reject;
+           };
+       }
+    };
diff --git a/TestData/simple_cli_preprocessor_test_file_not_found.golden b/TestData/simple_cli_preprocessor_test_file_not_found.golden
new file mode 100644
index 0000000..756a52a
--- /dev/null
+++ b/TestData/simple_cli_preprocessor_test_file_not_found.golden
@@ -0,0 +1 @@
+Preprocessor Error: Could not open simple.p for preprocessing
diff --git a/TestData/simple_cli_testa.golden b/TestData/simple_cli_testa.golden
new file mode 100644
index 0000000..3582111
--- /dev/null
+++ b/TestData/simple_cli_testa.golden
@@ -0,0 +1 @@
+Success
diff --git a/Tests/Support.swift b/Tests/Support.swift
index a2f827c..6f88b20 100644
--- a/Tests/Support.swift
+++ b/Tests/Support.swift
@@ -16,8 +16,12 @@
 // along with this program. If not, see <https://www.gnu.org/licenses/>.
 
 import Foundation
+import SystemPackage
 import Testing
 
+private let TestGoldenPath: FilePath.Component = FilePath.Component("TestData")
+private let TestGoldenExtension: String = ".golden"
+
 typealias Accessor =
   @convention(c) (
     _ outValue: UnsafeMutableRawPointer,
@@ -68,7 +72,6 @@ func swiftRun(withArgs args: [String]) throws -> String? {
   let path = swiftPath()!
   let child = Process()
   let so = Pipe()
-  let se = Pipe()
 
   child.standardOutput = so
   child.executableURL = path
@@ -90,7 +93,7 @@ func swiftRun(withArgs args: [String]) throws -> String? {
   return output
 }
 
-func swiftCliTestRunner(_ arg_gen: () -> [String], _ expected: String) async throws {
+func swiftCliTestRunner(_ arg_gen: () -> [String], withExpected expected: String) async throws {
   let args = arg_gen()
 
   let run_output = try! swiftRun(withArgs: args)
@@ -98,7 +101,17 @@ func swiftCliTestRunner(_ arg_gen: () -> [String], _ expected: String) async thr
   #expect(run_output == expected)
 }
 
+func swiftCliTestRunner(_ arg_gen: () -> [String], withExpectedPath expected_path: String) async throws {
+  let args = arg_gen()
 
+  let run_output = try! swiftRun(withArgs: args)
+
+  let expected_source_absolute = FilePath(FileManager().currentDirectoryPath).appending(TestGoldenPath).appending(expected_path + TestGoldenExtension)
+
+  let expected_output = try! String(contentsOfFile: expected_source_absolute.string)
+
+  #expect(run_output == expected_output)
+}
 
 @attached(peer) public macro CliTest() =
-  #externalMacro(module: "Macros", type: "CliTestDeclarationMacro")
\ No newline at end of file
+  #externalMacro(module: "Macros", type: "CliTestDeclarationMacro")
diff --git a/Tests/p4rseTests/CliTests/Cli.swift b/Tests/p4rseTests/CliTests/Cli.swift
index 3ac0b95..1c57fbc 100644
--- a/Tests/p4rseTests/CliTests/Cli.swift
+++ b/Tests/p4rseTests/CliTests/Cli.swift
@@ -23,4 +23,19 @@ import Testing
 @CliTest()
 func simple_cli_test() -> [String] {
     return ["p4ce", "--plain", "compile", "simple.p4", "-I", "TestData/Sources/"]
+}
+
+@CliTest()
+func simple_cli_testa() -> [String] {
+    return ["p4ce", "--plain", "compile", "simple.p4", "-I", "TestData/Sources/"]
+}
+
+@CliTest()
+func simple_cli_preprocessor_test() -> [String] {
+    return ["p4ce", "--plain", "preprocess", "simple.p4", "-I", "TestData/Sources/"]
+}
+
+@CliTest()
+func simple_cli_preprocessor_test_file_not_found() -> [String] {
+    return ["p4ce", "--plain", "preprocess", "simple.p", "-I", "TestData/Sources/"]
 }
\ No newline at end of file