feat(host): Allow nil setAttributes for buildDescribeInstancesInput (#79)

* Allow nil setAttributes

* move the nil check

---------

Co-authored-by: Delaine Rogers <delainerogers@dhcp-9-16-190-160.sjs-us.ibm.com>

plugin/service/host/plugin.go

@@ -644,6 +644,10 @@ func buildFilters(attrs *SetAttributes) ([]types.Filter, error) {
 }
 
 func buildDescribeInstancesInput(attrs *SetAttributes, dryRun bool) (*ec2.DescribeInstancesInput, error) {
+	if attrs == nil {
+		attrs = &SetAttributes{}
+	}
+
 	filters, err := buildFilters(attrs)
 	if err != nil {
 		return nil, fmt.Errorf("error building filters: %w", err)

plugin/service/host/plugin_test.go

@@ -2633,6 +2633,21 @@ func TestBuildDescribeInstancesInput(t *testing.T) {
 			require.Equal(tc.expected, actual)
 		})
 	}
+
+	t.Run("nil attrs, dry run", func(t *testing.T) {
+		require := require.New(t)
+		actual, err := buildDescribeInstancesInput(nil, true)
+		require.NoError(err)
+		require.Equal(&ec2.DescribeInstancesInput{
+			DryRun: aws.Bool(true),
+			Filters: []types.Filter{
+				{
+					Name:   aws.String("instance-state-name"),
+					Values: []string{string(types.InstanceStateNameRunning)},
+				},
+			},
+		}, actual)
+	})
 }
 
 func TestAwsInstanceToHost(t *testing.T) {