Add unit test

Tests/XCRemoteCacheTests/Commands/XCCCTests.swift

@@ -332,11 +332,27 @@ class TemplateBasedCCWrapperBuilderTests: FileXCTestCase {
         XCTAssertNotEqual(newFileOutputData, Data())
     }
 
+    func testPCHCompilationFallbacks() throws {
+        // Marker is empty to mimic the new file scenario
+        let pchFile = directory.appendingPathComponent("input.pch")
+        createValidPCCFile(pchFile)
+        arguments = ["-x", "objective-c-header", "-MF", dependencyFile.path, "-o", outputFile.path, pchFile.path]
+
+        try shellExec(Self.xccc.path, args: arguments, inDir: directory.path)
+
+        XCTAssertTrue(fileManager.fileExists(atPath: outputFile.path))
+    }
+
     /// Creates a simple C code in the location
     private func createValidCFile(_ location: URL) {
         fileManager.createFile(atPath: location.path, contents: "int main(){}".data(using: .utf8), attributes: nil)
     }
 
+    /// Creates a simple PCH code in the location
+    private func createValidPCCFile(_ location: URL) {
+        fileManager.createFile(atPath: location.path, contents: "#import <Availability.h>".data(using: .utf8), attributes: nil)
+    }
+
     /// Creates a C code that requires extra CUSTOM_STR clang macro to compile
     private func createInvalidCFile(_ location: URL) {
         fileManager.createFile(