Replace testify with gotest.tools (#553)

* vendor gotest.tools

* Run gotest.tools migration tools

* Fixup tests that were improperly converted

* Remove unused testify package vendors

providers/vic/operations/pod_starter_test.go

@@ -3,10 +3,10 @@ package operations
 import (
 	"testing"
 
-	"github.com/stretchr/testify/assert"
-
 	"github.com/virtual-kubelet/virtual-kubelet/providers/vic/proxy/mocks"
 	"github.com/vmware/vic/lib/apiservers/portlayer/client"
+	"gotest.tools/assert"
+	is "gotest.tools/assert/cmp"
 )
 
 func TestNewPodStarter(t *testing.T) {
@@ -18,16 +18,16 @@ func TestNewPodStarter(t *testing.T) {
 
 	// Positive Cases
 	s, err = NewPodStarter(client, ip)
-	assert.NotNil(t, s, "Expected non-nil creating a pod starter but received nil")
+	assert.Check(t, s != nil, "Expected non-nil creating a pod starter but received nil")
 
 	// Negative Cases
 	s, err = NewPodStarter(nil, ip)
-	assert.Nil(t, s, "Expected nil")
-	assert.Equal(t, err, PodStarterPortlayerClientError)
+	assert.Check(t, is.Nil(s), "Expected nil")
+	assert.Check(t, is.DeepEqual(err, PodStarterPortlayerClientError))
 
 	s, err = NewPodStarter(client, nil)
-	assert.Nil(t, s, "Expected nil")
-	assert.Equal(t, err, PodStarterIsolationProxyError)
+	assert.Check(t, is.Nil(s), "Expected nil")
+	assert.Check(t, is.DeepEqual(err, PodStarterIsolationProxyError))
 }
 
 //NOTE: The rest of PodStarter tests were handled in PodCreator's tests so there's no need for further tests.