Don't throw error for Kappa and test parameter print

gtsam/sfm/ShonanAveraging.cpp

@@ -346,6 +346,7 @@ static double Kappa(const BinaryMeasurement<T> &measurement) {
       std::cout << "Verification of optimality does not work with robust cost "
                    "function"
                 << std::endl;
+      sigma = 1;  // setting arbitrary value
     } else {
       throw std::invalid_argument(
           "Shonan averaging noise models must be isotropic (but robust losses "

gtsam/sfm/tests/testShonanAveraging.cpp

@@ -17,6 +17,7 @@
  */
 
 #include <CppUnitLite/TestHarness.h>
+#include <gtsam/base/TestableAssertions.h>
 #include <gtsam/sfm/ShonanAveraging.h>
 #include <gtsam/slam/BetweenFactor.h>
 #include <gtsam/slam/FrobeniusFactor.h>
@@ -329,7 +330,11 @@ TEST(ShonanAveraging2, noisyToyGraphWithHuber) {
   ShonanAveraging2::Parameters parameters(lmParams);
   auto measurements = parseMeasurements<Rot2>(g2oFile);
   parameters.setUseHuber(true);
-  parameters.print();
+  string parameters_print =
+      " ShonanAveragingParameters: \n alpha: 0\n beta: 1\n gamma: 0\n "
+      "useHuber: 1\n";
+  assert_print_equal(parameters_print, parameters);
+
   ShonanAveraging2 shonan(measurements, parameters);
   EXPECT_LONGS_EQUAL(4, shonan.nrUnknowns());