模拟 *ec2.DescribeVolumesOutput 的输出

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我目前正在尝试适应 tdd，并且在我当前正在从事的项目中，我正在尝试利用 aws 的 go sdk。这一切都很好，我以前用过它，但我目前正在尝试模拟 *ec2.describevolumesoutput 发送的值。

深入研究代码，我发现这是 *ec2.describevolumesoutput 的返回值：

type describevolumesoutput struct {
    _ struct{} `type:"structure"`

    // the nexttoken value to include in a future describevolumes request. when
    // the results of a describevolumes request exceed maxresults, this value can
    // be used to retrieve the next page of results. this value is null when there
    // are no more results to return.
    nexttoken *string `locationname:"nexttoken" type:"string"`

    // information about the volumes.
    volumes []*volume `locationname:"volumeset" locationnamelist:"item" type:"list"`
}

好吧..这很酷，但是我想要模拟的输出必须位于 volumes []*volumelocationname:"volumeset" locationnamelist:"item" type:"list"` 内部，所以让我们更深入地了解一下那是什么...

type Volume struct {
    _ struct{} `type:"structure"`

    // Information about the volume attachments.
    Attachments []*VolumeAttachment `locationName:"attachmentSet" locationNameList:"item" type:"list"`

    // The Availability Zone for the volume.
    AvailabilityZone *string `locationName:"availabilityZone" type:"string"`

    // The time stamp when volume creation was initiated.
    CreateTime *time.Time `locationName:"createTime" type:"timestamp"`

    // Indicates whether the volume will be encrypted.
    Encrypted *bool `locationName:"encrypted" type:"boolean"`

    // The number of I/O operations per second (IOPS) that the volume supports.
    // For Provisioned IOPS SSD volumes, this represents the number of IOPS that
    // are provisioned for the volume. For General Purpose SSD volumes, this represents
    // the baseline performance of the volume and the rate at which the volume accumulates
    // I/O credits for bursting. For more information, see Amazon EBS Volume Types
    // (https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/EBSVolumeTypes.html)
    // in the Amazon Elastic Compute Cloud User Guide.
    //
    // Constraints: Range is 100-16,000 IOPS for gp2 volumes and 100 to 64,000IOPS
    // for io1 volumes, in most Regions. The maximum IOPS for io1 of 64,000 is guaranteed
    // only on Nitro-based instances (https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/instance-types.html#ec2-nitro-instances).
    // Other instance families guarantee performance up to 32,000 IOPS.
    //
    // Condition: This parameter is required for requests to create io1 volumes;
    // it is not used in requests to create gp2, st1, sc1, or standard volumes.
    Iops *int64 `locationName:"iops" type:"integer"`

    // The full ARN of the AWS Key Management Service (AWS KMS) customer master
    // key (CMK) that was used to protect the volume encryption key for the volume.
    KmsKeyId *string `locationName:"kmsKeyId" type:"string"`

    // The size of the volume, in GiBs.
    Size *int64 `locationName:"size" type:"integer"`

    // The snapshot from which the volume was created, if applicable.
    SnapshotId *string `locationName:"snapshotId" type:"string"`

    // The volume state.
    State *string `locationName:"status" type:"string" enum:"VolumeState"`

    // Any tags assigned to the volume.
    Tags []*Tag `locationName:"tagSet" locationNameList:"item" type:"list"`

    // The ID of the volume.
    VolumeId *string `locationName:"volumeId" type:"string"`

    // The volume type. This can be gp2 for General Purpose SSD, io1 for Provisioned
    // IOPS SSD, st1 for Throughput Optimized HDD, sc1 for Cold HDD, or standard
    // for Magnetic volumes.
    VolumeType *string `locationName:"volumeType" type:"string" enum:"VolumeType"`
}

不错！这看起来像是我想模拟其值的一些数据！

但在过去的几天里，我没有运气真正嘲笑这些价值观。它们是如此嵌套以至于这种类型的嘲笑不值得付出努力吗？即使尝试使用 github.com/aws/aws-sdk-go/service/ec2/ec2iface 似乎也无法帮助我了解如何正确打包一些模拟值返回以进行测试。我对 tdd 的态度是错的吗？我错过了一些非常明显的东西吗？我真的没有示例代码可以展示，因为我现在不再明白我要做什么。

有人可能有一个他们如何嘲笑这个的例子吗？

解决方案

无法模拟类型，您只能模拟接口的实现。在您的情况下，我假设您正在尝试拨打 DescribeVolumes 并在响应中获取您构建的值。
为此，您需要创建一个类似

type mockec2api struct {
    ec2iface.ec2api // embedding of the interface is needed to skip implementation of all methods
    describevolumesmethod func(*ec2.describevolumesinput) (*ec2.describevolumesoutput, error)
}

func (m *mockec2api) describevolumes(in *ec2.describevolumesinput) (*ec2.describevolumesoutput, error) {
    if m.describevolumesmethod != nil {
        return m.describevolumesmethod(in)
    }
    return nil, nil // return any value you think is good for you
}

在测试中创建 mockec2api 实例而不是真正的 ec2.ec2 并为其提供将被调用并返回准备好的 ec2.describevolumesoutput 结果的函数

...
ec2 := &MockEC2API{
    DescribeVolumesMethod: func(*ec2.DescribeVolumesInput) (*ec2.DescribeVolumesOutput, error) {
        return &ec2.DescribeVolumesOutput{...your initialization...}, nil
    }
}
...
output, err := ec2.DescribeVolumes(in) // this output will be your prepared initialization

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