Use require for Error and NoError

Assert keeps going after failure, but require immediately fails
the tests, making it easier to find the output related to the test
failure, rather than having to comb through a bunch of subsequent
assertion failures. For equality tests, we may or may not want to
continue, but for error checks we almost always want to immediately
fail the test. Exceptions can be changed as-needed.

kyaml/kio/tree_test.go

@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
 	. "sigs.k8s.io/kustomize/kyaml/kio"
 	"sigs.k8s.io/kustomize/kyaml/yaml"
 )
@@ -574,6 +575,6 @@ metadata:
 		Inputs:  []Reader{&ByteReader{Reader: bytes.NewBufferString(in)}},
 		Outputs: []Writer{TreeWriter{Writer: out}},
 	}.Execute()
-	assert.Error(t, err)
+	require.Error(t, err)
 	assert.Equal(t, "owner 'Application myapp-staging/nginx' not found in input, but found as an owner of input objects", err.Error())
 }