Fix tiny_solver_test

Verify that the final cost is small enough instead of the norm
of the residual vector.

Change-Id: I9591d97d3e8f1c71067d99270967f1e593889843

internal/ceres/tiny_solver_test.cc

diff --git a/internal/ceres/tiny_solver_test.cc b/internal/ceres/tiny_solver_test.cc
index 747e20d..f92b186 100644
--- a/internal/ceres/tiny_solver_test.cc
+++ b/internal/ceres/tiny_solver_test.cc
@@ -146,13 +146,11 @@
   Vector x = x0;
   Vec2 residuals;
   f(x.data(), residuals.data(), NULL);
-  EXPECT_GT(residuals.norm(), 1e-10);
+  EXPECT_GT(residuals.squaredNorm() / 2.0, 1e-10);
 
   TinySolver<Function> solver;
   solver.Solve(f, &x);
-
-  f(x.data(), residuals.data(), NULL);
-  EXPECT_NEAR(0.0, residuals.norm(), 1e-10);
+  EXPECT_NEAR(0.0, solver.summary.final_cost, 1e-10);
 }
 
 // A test case for when the cost function is statically sized.