Partial extension API server store + control over printed columns (#432)

* Checkpoint

* Add support for custom columns

* Remove old Store and Delegate abstraction

* Fix nits and rewording

* Remove unused mock file

* Update documentation for extension api server

* Remove the need for scheme for ConvertListOptions

* Rename store to utils

* fixup! Remove the need for scheme for ConvertListOptions

* Move watch helper to tests

* Add convertError at a few places

* Ignore misspell on creater

* Fix comments and remove unused params

* Add convertError to missing error returns

* Fix watcher implementation

* Document request.UserFrom and request.NamespaceFrom

pkg/ext/utils_test.go

@@ -0,0 +1,69 @@
+package ext
+
+import (
+	"fmt"
+	"net/http"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	apierrors "k8s.io/apimachinery/pkg/api/errors"
+	metainternalversion "k8s.io/apimachinery/pkg/apis/meta/internalversion"
+	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
+)
+
+func TestConvertListOptions(t *testing.T) {
+	internal := &metainternalversion.ListOptions{
+		ResourceVersion: "foo",
+		Watch:           true,
+	}
+	expected := &metav1.ListOptions{
+		ResourceVersion: "foo",
+		Watch:           true,
+	}
+	got, err := ConvertListOptions(internal)
+	assert.NoError(t, err)
+	assert.Equal(t, expected, got)
+}
+
+func TestConvertError(t *testing.T) {
+	tests := []struct {
+		name   string
+		input  error
+		output error
+	}{
+		{
+			name: "api status error",
+			input: &apierrors.StatusError{
+				ErrStatus: metav1.Status{
+					Code:   http.StatusNotFound,
+					Reason: metav1.StatusReasonNotFound,
+				},
+			},
+			output: &apierrors.StatusError{
+				ErrStatus: metav1.Status{
+					Code:   http.StatusNotFound,
+					Reason: metav1.StatusReasonNotFound,
+				},
+			},
+		},
+		{
+			name:  "generic error",
+			input: assert.AnError,
+			output: &apierrors.StatusError{ErrStatus: metav1.Status{
+				Status: metav1.StatusFailure,
+				Code:   http.StatusInternalServerError,
+				Reason: metav1.StatusReasonInternalError,
+				Details: &metav1.StatusDetails{
+					Causes: []metav1.StatusCause{{Message: assert.AnError.Error()}},
+				},
+				Message: fmt.Sprintf("Internal error occurred: %v", assert.AnError),
+			}},
+		},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			assert.Equal(t, tt.output, convertError(tt.input))
+		})
+	}
+}