tests(awsprovider): Add unit tests for getUsageType

This adds a unit test for `getUsageType` with four conditions to check.
The tests will help ensure that `getUsageType` will return the correct
values through a range of different scenarios.

Signed-off-by: pokom <mark.poko@grafana.com>

pkg/cloud/awsprovider.go

@@ -55,7 +55,9 @@ const (
 	InUseState    = "in-use"
 	AttachedState = "attached"
 
-	AWSHourlyPublicIPCost = 0.005
+	AWSHourlyPublicIPCost    = 0.005
+	EKSCapacityTypeLabel     = "eks.amazonaws.com/capacityType"
+	EKSCapacitySpotTypeValue = "SPOT"
 )
 
 var (
@@ -664,7 +666,7 @@ func (k *awsKey) Features() string {
 // If the instance is a spot instance, it will return PreemptibleType
 // Otherwise returns an empty string
 func (k *awsKey) getUsageType(labels map[string]string) string {
-	if label, ok := labels["eks.amazonaws.com/capacityType"]; ok && label == "SPOT" {
+	if label, ok := labels[EKSCapacityTypeLabel]; ok && label == EKSCapacitySpotTypeValue {
 		// We currently write out spot instances as "preemptible" in the pricing data, so these need to match
 		return PreemptibleType
 	}

pkg/cloud/awsprovider_test.go

@@ -0,0 +1,66 @@
+package cloud
+
+import "testing"
+
+func Test_awsKey_getUsageType(t *testing.T) {
+	type fields struct {
+		Labels     map[string]string
+		ProviderID string
+	}
+	type args struct {
+		labels map[string]string
+	}
+	tests := []struct {
+		name   string
+		fields fields
+		args   args
+		want   string
+	}{
+		{
+			// test with no labels should return false
+			name: "Label does not have the capacityType label associated with it",
+			args: args{
+				labels: map[string]string{},
+			},
+			want: "",
+		},
+		{
+			name: "label with a capacityType set to empty string should return empty string",
+			args: args{
+				labels: map[string]string{
+					EKSCapacityTypeLabel: "",
+				},
+			},
+			want: "",
+		},
+		{
+			name: "label with capacityType set to a random value should return empty string",
+			args: args{
+				labels: map[string]string{
+					EKSCapacityTypeLabel: "TEST_ME",
+				},
+			},
+			want: "",
+		},
+		{
+			name: "label with capacityType set to spot should return spot",
+			args: args{
+				labels: map[string]string{
+					EKSCapacityTypeLabel: EKSCapacitySpotTypeValue,
+				},
+			},
+			want: PreemptibleType,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			k := &awsKey{
+				Labels:     tt.fields.Labels,
+				ProviderID: tt.fields.ProviderID,
+			}
+			if got := k.getUsageType(tt.args.labels); got != tt.want {
+				t.Errorf("getUsageType() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}