How to use the moto.mock_ec2 function in moto

@mock_ec2
def test_elastic_network_interfaces_get_by_vpc_id():
    ec2 = boto3.resource("ec2", region_name="us-west-2")
    ec2_client = boto3.client("ec2", region_name="us-west-2")

    vpc = ec2.create_vpc(CidrBlock="10.0.0.0/16")
    subnet = ec2.create_subnet(
        VpcId=vpc.id, CidrBlock="10.0.0.0/24", AvailabilityZone="us-west-2a"
    )

    eni1 = ec2.create_network_interface(
        SubnetId=subnet.id, PrivateIpAddress="10.0.10.5"
    )

    # The status of the new interface should be 'available'
    waiter = ec2_client.get_waiter("network_interface_available")
    waiter.wait(NetworkInterfaceIds=[eni1.id])

@mock_ec2
def test_create_subnet_with_invalid_availability_zone():
    ec2 = boto3.resource("ec2", region_name="us-west-1")
    client = boto3.client("ec2", region_name="us-west-1")

    vpc = ec2.create_vpc(CidrBlock="10.0.0.0/16")

    subnet_availability_zone = "asfasfas"
    with assert_raises(ClientError) as ex:
        subnet = client.create_subnet(
            VpcId=vpc.id,
            CidrBlock="10.0.0.0/24",
            AvailabilityZone=subnet_availability_zone,
        )
    assert str(ex.exception).startswith(
        "An error occurred (InvalidParameterValue) when calling the CreateSubnet "
        "operation: Value ({}) for parameter availabilityZone is invalid. Subnets can currently only be created in the following availability zones: ".format(

    @mock_ec2
    @mock_lambda
    def test_invoke_function_get_ec2_volume():
        conn = boto3.resource("ec2", "us-west-2")
        vol = conn.create_volume(Size=99, AvailabilityZone="us-west-2")
        vol = conn.Volume(vol.id)

        conn = boto3.client("lambda", "us-west-2")
        conn.create_function(
            FunctionName="testFunction",
            Runtime="python2.7",
            Role="test-iam-role",
            Handler="lambda_function.lambda_handler",
            Code={"ZipFile": get_test_zip_file2()},
            Description="test lambda function",
            Timeout=3,
            MemorySize=128,

@mock_ec2
def test_request_spot_instances_default_arguments():
    """
    Test that moto set the correct default arguments
    """
    conn = boto3.client("ec2", "us-east-1")

    request = conn.request_spot_instances(
        SpotPrice="0.5", LaunchSpecification={"ImageId": "ami-abcd1234"}
    )

    requests = conn.describe_spot_instance_requests()["SpotInstanceRequests"]
    requests.should.have.length_of(1)
    request = requests[0]

    request["State"].should.equal("open")
    request["SpotPrice"].should.equal("0.5")

@mock_ec2
@mock_elb
def test_deregister_instances_boto3():
    ec2 = boto3.resource("ec2", region_name="us-east-1")
    response = ec2.create_instances(ImageId="ami-1234abcd", MinCount=2, MaxCount=2)
    instance_id1 = response[0].id
    instance_id2 = response[1].id

    client = boto3.client("elb", region_name="us-east-1")
    client.create_load_balancer(
        LoadBalancerName="my-lb",
        Listeners=[{"Protocol": "http", "LoadBalancerPort": 80, "InstancePort": 8080}],
        AvailabilityZones=["us-east-1a", "us-east-1b"],
    )
    client.register_instances_with_load_balancer(
        LoadBalancerName="my-lb",
        Instances=[{"InstanceId": instance_id1}, {"InstanceId": instance_id2}],

@mock_ec2
def test_delete_stack_by_name():
    cf_conn = boto3.client("cloudformation", region_name="us-east-1")
    cf_conn.create_stack(StackName="test_stack", TemplateBody=dummy_template_json)

    cf_conn.describe_stacks()["Stacks"].should.have.length_of(1)
    cf_conn.delete_stack(StackName="test_stack")
    cf_conn.describe_stacks()["Stacks"].should.have.length_of(0)

def amis():
    """AMI mock service"""
    mock = mock_ec2()
    mock.start()
    client = session.client('ec2')
    reservation = client.run_instances(ImageId='ami-1234abcd', MinCount=1, MaxCount=1)
    instance = reservation.get('Instances')[0]
    image_id = client.create_image(InstanceId=instance.get('InstanceId'),
                                   Name="test-ami",
                                   Description="this is a test ami")
    yield client.describe_images()
    mock.stop()

@mock_ec2
def test_create_subnet_with_invalid_cidr_block_parameter():
    ec2 = boto3.resource("ec2", region_name="us-west-1")

    vpc = ec2.create_vpc(CidrBlock="10.0.0.0/16")
    vpc.reload()
    vpc.is_default.shouldnt.be.ok

    subnet_cidr_block = "1000.1.0.0/20"
    with assert_raises(ClientError) as ex:
        subnet = ec2.create_subnet(VpcId=vpc.id, CidrBlock=subnet_cidr_block)
    str(ex.exception).should.equal(
        "An error occurred (InvalidParameterValue) when calling the CreateSubnet "
        "operation: Value ({}) for parameter cidrBlock is invalid. This is not a valid CIDR block.".format(
            subnet_cidr_block
        )

@mock_ec2
def test_latest_meta_data():
    res = requests.get("{0}/latest/meta-data/".format(BASE_URL))
    res.content.should.equal(b"iam")

@mock_ec2
def test_create_tag_empty_resource():
    # create ec2 client in us-west-1
    client = boto3.client("ec2", region_name="us-west-1")
    # create tag with empty resource
    with assert_raises(ClientError) as ex:
        client.create_tags(Resources=[], Tags=[{"Key": "Value"}])
    ex.exception.response["Error"]["Code"].should.equal("MissingParameter")
    ex.exception.response["Error"]["Message"].should.equal(
        "The request must contain the parameter resourceIdSet"
    )