首先，我应该警告您Magento目前不支持SOAP v2格式，api/v2_soap/?wsdl只是

At first I should warn you that Magento doesn't support SOAP v2 format for now, api/v2_soap/?wsdl is just second version of soap api.

1.

<models>
    <test>
        <class>ABT_Test_Model</class>
    </test>
</models>

由于要编写的模块不是核心模块，因此应编写<abt_test>

Because you are writing module which isn't core, you should write <abt_test>

2. <model>test/api</model>.在您的情况下应为<model>abt_test/api</model>.

2.<model>test/api</model>. Should be <model>abt_test/api</model> in your case.

3. <acl>test/foo</acl>.

此acl部分是否存在于您的adminhtml.xml中?

Does this acl section exist in your adminhtml.xml?