Add new tests to presubmit, fix errors

perf/go/vec/vec_test.go

 package vec
 
 import (
         "math"
         "testing"
 )
 
 func near(a, b float64) bool {
         return math.Abs(a-b) < 0.001
 }
@@ skipping 97 matching lines @@
                         Idx:   0,
                 },
                 {
                         Slice: []float64{4},
                         Idx:   -1,
                 },
         }
         for _, tc := range testCases {
                 _, err := FillAt(tc.Slice, tc.Idx)
                 if err == nil {
-                        t.Fatalf("Expected %q to fail FillAt.", tc)
+                        t.Fatalf("Expected \"%v\" to fail FillAt.", tc)
                 }
         }
 }