psi: wrote testing for get gps from pmt byte slice

stream/mts/psi/op.go

@@ -92,6 +92,19 @@ func TimeOf(p []byte) (t uint64, err error) {
 	return t, nil
 }
 
+// TimeOf takes a byte slice representation of a psi-pmt and extracts it's
+// timestamp, returning as a uint64 if it exists, otherwise returning 0 and nil
+// if it does not exist
+func GpsOf(p []byte) (g string, err error) {
+	err = ChkGps(p)
+	if err != nil {
+		return "", err
+	}
+	gBytes := p[gpsDataIndx : gpsDataIndx+gpsDataSize]
+	g = string(gBytes)
+	return g, nil
+}
+
 // GpsStrBytes take a string of gps data and converts to a 32 byte slice -
 // easy update of slice representation of a pmt with gps descriptor
 func GpsStrBytes(l string) (out []byte) {

stream/mts/psi/psi_test.go

@@ -39,8 +39,8 @@ const (
 
 // GPS string for testing
 const (
-	gpsTstStr1 = "$GPGGA,123519,4807.038,N,01131.000,E,1,08,0.9,545.4,M,46.9,M,,*47"
-	gpsTstStr2 = "$GPGGA,183710,4902.048,N,02171.020,E,1,09,0.5,547.2,M,43.4,M,,*42"
+	gpsTstStr1 = "$GPGGA,123519,4807.038,N,01131.0"
+	gpsTstStr2 = "$GPGGA,183710,4902.048,N,02171.0"
 )
 
 // err message
@@ -240,6 +240,21 @@ func TestTimeGet(t *testing.T) {
 	}
 }
 
+func TestGpsGet(t *testing.T) {
+	pb := StdPmtTimeGps.Bytes()
+	err := UpdateGps(pb, gpsTstStr1)
+	if err != nil {
+		t.Errorf("Error for TestGpsGet UpdateGps(pb, gpsTstStr1): %v", err)
+	}
+	g, err := GpsOf(pb)
+	if err != nil {
+		t.Errorf("Error for TestGpsGet GpsOf(pb): %v", err)
+	}
+	if g != gpsTstStr1 {
+		t.Errorf(errCmp, "TestGpsGet", gpsTstStr1, g)
+	}
+}
+
 // TestGpsUpdate checks to see if we can update the gps string in a pmt correctly
 func TestGpsUpdate(t *testing.T) {
 	cpy := make([]byte, len(pmtTimeGpsBytes1))