Add unit tests for VPC resolver

pkg/networking/vpc_resolver.go

@@ -34,7 +34,7 @@ type defaultVPCResolver struct {
 }
 
 func (r *defaultVPCResolver) ResolveCIDRs(ctx context.Context) ([]string, error) {
-	vpcs, err := r.ec2Client.DescribeVpcs(&ec2.DescribeVpcsInput{
+	vpcs, err := r.ec2Client.DescribeVpcsWithContext(ctx, &ec2.DescribeVpcsInput{
 		VpcIds: []*string{awssdk.String(r.vpcID)},
 	})
 	if err != nil {
@@ -51,5 +51,4 @@ func (r *defaultVPCResolver) ResolveCIDRs(ctx context.Context) ([]string, error)
 	}
 
 	return vpcCIDRs, nil
-
 }

pkg/networking/vpc_resolver_test.go

@@ -0,0 +1,125 @@
+package networking
+
+import (
+	"context"
+	awssdk "github.com/aws/aws-sdk-go/aws"
+	ec2sdk "github.com/aws/aws-sdk-go/service/ec2"
+	"github.com/golang/mock/gomock"
+	"github.com/pkg/errors"
+	"github.com/stretchr/testify/assert"
+	"sigs.k8s.io/aws-load-balancer-controller/pkg/aws/services"
+	"testing"
+)
+
+func Test_defaultVPCResolver_ResolveCIDRs(t *testing.T) {
+	type descriveVpcsCall struct {
+		input  *ec2sdk.DescribeVpcsInput
+		output *ec2sdk.DescribeVpcsOutput
+		err    error
+	}
+	tests := []struct {
+		name             string
+		vpcID            string
+		want             []string
+		wantErr          error
+		descriveVpcsCall descriveVpcsCall
+	}{
+		{
+			name:    "vpc cidr discovery",
+			vpcID:   "vpc-01xxx2",
+			want:    []string{"192.160.0.0/16"},
+			wantErr: nil,
+			descriveVpcsCall: descriveVpcsCall{
+				input: &ec2sdk.DescribeVpcsInput{
+					VpcIds: []*string{awssdk.String("vpc-01xxx2")},
+				},
+				output: &ec2sdk.DescribeVpcsOutput{
+					Vpcs: []*ec2sdk.Vpc{
+						{
+							CidrBlockAssociationSet: []*ec2sdk.VpcCidrBlockAssociation{
+								{
+									CidrBlock: awssdk.String("192.160.0.0/16"),
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+		{
+			name:    "unable to describe VPC",
+			vpcID:   "vpc-01xxx3",
+			wantErr: errors.Wrapf(errors.New("aws error"), "unable to describe VPC"),
+			descriveVpcsCall: descriveVpcsCall{
+				input: &ec2sdk.DescribeVpcsInput{
+					VpcIds: []*string{awssdk.String("vpc-01xxx3")},
+				},
+				err: errors.New("aws error"),
+			},
+		},
+		{
+			name:    "unable to find matching VPC",
+			vpcID:   "vpc-01xxx4",
+			wantErr: errors.New("unable to find matching VPC \"vpc-01xxx4\""),
+			descriveVpcsCall: descriveVpcsCall{
+				input: &ec2sdk.DescribeVpcsInput{
+					VpcIds: []*string{awssdk.String("vpc-01xxx4")},
+				},
+				output: &ec2sdk.DescribeVpcsOutput{},
+			},
+		},
+		{
+			name:    "multiple CIDRs",
+			vpcID:   "vpc-01xxx2",
+			want:    []string{"192.160.0.0/16", "100.64.0.0/16", "100.65.0.0/16", "100.66.0.0/24"},
+			wantErr: nil,
+			descriveVpcsCall: descriveVpcsCall{
+				input: &ec2sdk.DescribeVpcsInput{
+					VpcIds: []*string{awssdk.String("vpc-01xxx2")},
+				},
+				output: &ec2sdk.DescribeVpcsOutput{
+					Vpcs: []*ec2sdk.Vpc{
+						{
+							CidrBlockAssociationSet: []*ec2sdk.VpcCidrBlockAssociation{
+								{
+									CidrBlock: awssdk.String("192.160.0.0/16"),
+								},
+								{
+									CidrBlock: awssdk.String("100.64.0.0/16"),
+								},
+								{
+									CidrBlock: awssdk.String("100.65.0.0/16"),
+								},
+								{
+									CidrBlock: awssdk.String("100.66.0.0/24"),
+								},
+							},
+						},
+					},
+				},
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			ctrl := gomock.NewController(t)
+			defer ctrl.Finish()
+
+			ec2Client := services.NewMockEC2(ctrl)
+			ec2Client.EXPECT().DescribeVpcsWithContext(gomock.Any(), tt.descriveVpcsCall.input).Return(
+				tt.descriveVpcsCall.output, tt.descriveVpcsCall.err)
+			vpcResolver := &defaultVPCResolver{
+				ec2Client: ec2Client,
+				vpcID:     tt.vpcID,
+			}
+			got, err := vpcResolver.ResolveCIDRs(context.Background())
+			if tt.wantErr != nil {
+				assert.EqualError(t, err, tt.wantErr.Error())
+			} else {
+				assert.NoError(t, err)
+				assert.Equal(t, tt.want, got)
+			}
+
+		})
+	}
+}