Comparison expressions don't evaluate operand type

[diehlaws]

Description

Comparison expressions do not evaluate as expected in cases where one operand is a literal value and the other is a pointer to a value. This results in expressions such as AutoScalingGroups[].[length(Instances[?LifecycleState=='InService'] used in the AWS SDK for Go's Autoscaling waiter WaitUntilGroupInService not evaluating correctly since LifecycleState is a pointer to a string that is being evaluated against the literal string InService.

Steps to reproduce

Save this code as main_test.go and run go test -v:

package main

import (
    "testing"

    "github.com/aws/aws-sdk-go/aws"
    "github.com/aws/aws-sdk-go/aws/awsutil"
    "github.com/aws/aws-sdk-go/service/autoscaling"
)

func TestWaitUntilGroupInService(t *testing.T) {
    mockResponse := &autoscaling.DescribeAutoScalingGroupsOutput{
        AutoScalingGroups: []*autoscaling.Group{
            &autoscaling.Group{
                Instances: []*autoscaling.Instance{
                    &autoscaling.Instance{
                        LifecycleState: aws.String("InService"),
                    },
                    &autoscaling.Instance{
                        LifecycleState: aws.String("InService"),
                    },
                },
                MaxSize:         aws.Int64(4),
                MinSize:         aws.Int64(2),
                DesiredCapacity: aws.Int64(2),
            },
            &autoscaling.Group{
                Instances: []*autoscaling.Instance{
                    &autoscaling.Instance{
                        LifecycleState: aws.String("InService"),
                    },
                    &autoscaling.Instance{
                        LifecycleState: aws.String("Pending"),
                    },
                },
                MaxSize:         aws.Int64(4),
                MinSize:         aws.Int64(2),
                DesiredCapacity: aws.Int64(2),
            },
        },
    }

    var testCases = []struct {
        expect []interface{}
        data   interface{}
        path   string
    }{
        {[]interface{}{true}, mockResponse, "contains(AutoScalingGroups[].[length(Instances[?LifecycleState=='InService']) >= MinSize][], `false`)"},
        {[]interface{}{true, false}, mockResponse, "AutoScalingGroups[].[length(Instances[?LifecycleState=='InService']) >= MinSize][]"},
        {[]interface{}{2, 1}, mockResponse, "AutoScalingGroups[].[length(Instances[?LifecycleState=='InService'])][]"},
    }
    for i, c := range testCases {
        v, err := awsutil.ValuesAtPath(c.data, c.path)
        if err != nil {
            t.Errorf("case %v, expected no error, %v", i, c.path)
        }
        if e, a := c.expect, v; !awsutil.DeepEqual(e, a) {

            t.Errorf("case %v, %v, expected: %#v, but got: %#v", i, c.path, e, a)
        }
    }
}

$ go get -u github.com/aws/aws-sdk-go

$ go test -v
=== RUN   TestWaitUntilGroupInService
--- FAIL: TestWaitUntilGroupInService (0.00s)
    main_test.go:59: case 0, contains(AutoScalingGroups[].[length(Instances[?LifecycleState=='InService']) >= MinSize][], `false`), expected: []interface {}{true}, but got: []interface {}{false}
    main_test.go:59: case 1, AutoScalingGroups[].[length(Instances[?LifecycleState=='InService']) >= MinSize][], expected: []interface {}{true, false}, but got: []interface {}{}
    main_test.go:59: case 2, AutoScalingGroups[].[length(Instances[?LifecycleState=='InService'])][], expected: []interface {}{2, 1}, but got: []interface {}{0, 0}
FAIL
exit status 1
FAIL    _/Users/masayuki-morita/work/tmp/20190228       0.019s

Related items

Originating issue: aws/aws-sdk-go#2478
Related to #15 and #20.

[tiffanyfay]

Hey, wanted to see if there was an update on this, thanks! @jamesls