Switch to ginkgo/gomega for tests

This switches over to ginkgo/gomega for tests, which makes writing
certain tests easier/more fluent in the future.

vendor/github.com/kubernetes-incubator/metrics-server/pkg/provider/interfaces.go

@@ -0,0 +1,63 @@
+// Copyright 2018 The Kubernetes Authors.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package provider
+
+import (
+	"time"
+
+	corev1 "k8s.io/api/core/v1"
+	apitypes "k8s.io/apimachinery/pkg/types"
+	metrics "k8s.io/metrics/pkg/apis/metrics"
+)
+
+// MetricsProvider is both a PodMetricsProvider and a NodeMetricsProvider
+type MetricsProvider interface {
+	PodMetricsProvider
+	NodeMetricsProvider
+}
+
+// TimeSpan represents the timing information for a metric, which was
+// potentially calculated over some window of time (e.g. for CPU usage rate).
+type TimeInfo struct {
+	// NB: we consider the earliest timestamp amongst multiple containers
+	// for the purposes of determining if a metric is tained by a time
+	// period, like pod startup (used by things like the HPA).
+
+	// Timestamp is the time at which the metrics were initially collected.
+	// In the case of a rate metric, it should be the timestamp of the last
+	// data point used in the calculation.  If it represents multiple metric
+	// points, it should be the earliest such timestamp from all of the points.
+	Timestamp time.Time
+
+	// Window represents the window used to calculate rate metrics associated
+	// with this timestamp.
+	Window time.Duration
+}
+
+// PodMetricsProvider knows how to fetch metrics for the containers in a pod.
+type PodMetricsProvider interface {
+	// GetContainerMetrics gets the latest metrics for all containers in each listed pod,
+	// returning both the metrics and the associated collection timestamp.
+	// If a pod is missing, the container metrics should be nil for that pod.
+	GetContainerMetrics(pods ...apitypes.NamespacedName) ([]TimeInfo, [][]metrics.ContainerMetrics, error)
+}
+
+// NodeMetricsProvider knows how to fetch metrics for a node.
+type NodeMetricsProvider interface {
+	// GetNodeMetrics gets the latest metrics for the given nodes,
+	// returning both the metrics and the associated collection timestamp.
+	// If a node is missing, the resourcelist should be nil for that node.
+	GetNodeMetrics(nodes ...string) ([]TimeInfo, []corev1.ResourceList, error)
+}