diff --git a/pkg/collector/fake_collector_test.go b/pkg/collector/fake_collector_test.go
new file mode 100644
index 00000000..1077c6ca
--- /dev/null
+++ b/pkg/collector/fake_collector_test.go
@@ -0,0 +1,57 @@
+package collector
+
+import (
+	"time"
+
+	autoscalingv2 "k8s.io/api/autoscaling/v2beta2"
+	"k8s.io/apimachinery/pkg/api/resource"
+	"k8s.io/metrics/pkg/apis/custom_metrics"
+)
+
+type FakeCollectorPlugin struct {
+	metrics []CollectedMetric
+	config  map[string]string
+}
+
+type FakeCollector struct {
+	metrics  []CollectedMetric
+	interval time.Duration
+	stub     func() ([]CollectedMetric, error)
+}
+
+func (c *FakeCollector) GetMetrics() ([]CollectedMetric, error) {
+	if c.stub != nil {
+		v, err := c.stub()
+		return v, err
+	}
+
+	return c.metrics, nil
+}
+
+func (FakeCollector) Interval() time.Duration {
+	return time.Minute
+}
+
+func (p *FakeCollectorPlugin) NewCollector(
+	hpa *autoscalingv2.HorizontalPodAutoscaler,
+	config *MetricConfig,
+	interval time.Duration,
+) (Collector, error) {
+
+	p.config = config.Config
+	return &FakeCollector{metrics: p.metrics, interval: interval}, nil
+}
+
+func makePlugin(metric int) *FakeCollectorPlugin {
+	return &FakeCollectorPlugin{
+		metrics: []CollectedMetric{
+			{
+				Custom: custom_metrics.MetricValue{Value: *resource.NewQuantity(int64(metric), resource.DecimalSI)},
+			},
+		},
+	}
+}
+
+func makeCollectorWithStub(f func() ([]CollectedMetric, error)) *FakeCollector {
+	return &FakeCollector{stub: f}
+}
diff --git a/pkg/collector/skipper_collector_test.go b/pkg/collector/skipper_collector_test.go
index cbe31462..46f2097f 100644
--- a/pkg/collector/skipper_collector_test.go
+++ b/pkg/collector/skipper_collector_test.go
@@ -658,38 +658,3 @@ func makeConfig(resourceName, namespace, kind, backend string, fakedAverage bool
 	}
 	return config
 }
-
-type FakeCollectorPlugin struct {
-	metrics []CollectedMetric
-	config  map[string]string
-}
-
-type FakeCollector struct {
-	metrics []CollectedMetric
-}
-
-func (c *FakeCollector) GetMetrics() ([]CollectedMetric, error) {
-	return c.metrics, nil
-}
-
-func (FakeCollector) Interval() time.Duration {
-	return time.Minute
-}
-
-func (p *FakeCollectorPlugin) NewCollector(hpa *autoscalingv2.HorizontalPodAutoscaler, config *MetricConfig, interval time.Duration) (Collector, error) {
-	if p.config != nil {
-		return nil, fmt.Errorf("config already assigned once: %v", p.config)
-	}
-	p.config = config.Config
-	return &FakeCollector{metrics: p.metrics}, nil
-}
-
-func makePlugin(metric int) *FakeCollectorPlugin {
-	return &FakeCollectorPlugin{
-		metrics: []CollectedMetric{
-			{
-				Custom: custom_metrics.MetricValue{Value: *resource.NewQuantity(int64(metric), resource.DecimalSI)},
-			},
-		},
-	}
-}