     }
 
     func testCompetitionIDHeader() {
-        let header = IGCHeaderField.parseHLine(hLine: tailfinNumberString)
+        guard let header = IGCHeaderField.parseHLine(hLine: tailfinNumberString) else { XCTFail("expecting a comp ID header but got nil"); return }
         switch header {
         case .competitionID(let tailfin):
             print("glider registration \(tailfin)")

    }

    func testPilotHeader() {
        let pilotHeader = IGCHeaderField.parseHLine(hLine: pilotHeaderString)
        switch pilotHeader {
        case .pilotInCharge(let name):
            print("pilot name \(name)")

    }

    func testCompetitionClassHeader() {
        guard let header = IGCHeaderField.parseHLine(hLine: competitionClassString) else { XCTFail("expecting a class header but got nil"); return }
        switch header {
        case .competitionClass(let cClass):
            print("competition class \(cClass)")
