Attribute Macro faux::create

#[create]

Transforms a struct into a mockable version of itself.

It creates an associated function for the tagged struct called faux and masks the original definition of the struct by changing its name.

Use cargo-expand to see what your struct expands to after the macro.

Requirements

This macro deliberately fails to compile if any of the struct's fields are not private. Otherwise, a user of the struct could try to access the field directly when it no longer exists in the transformed version.

Only methods within impl blocks tagged by #[methods] may use any of the struct fields.

Usage

#[faux::create]
pub struct MyStruct {
    a: i32,
    b: Vec<u32>,
}

#[faux::methods]
impl MyStruct {
    /* methods go here */
}

// creates a mock out of MyStruct
let my_mock = MyStruct::faux();

Attribute arguments

self_type

Allowed values:

• #[create(self_type = "Rc")]
• #[create(self_type = "Arc")]
• #[create(self_type = "Box")]
• #[create(self_type = "Owned")]
  • this is the default and not necessary

Indicates how to wrap the real value of the struct when not being mocked, e.g., wrap an owned instance vs an Rc<>. faux will guide to use this attribute when needed through either a compile time error or a panic. Do not use unless faux asks you to.

Be default faux wraps owned instance of your struct (i.e., MyStruct). However, sometimes this is not ideal if the only interactions for this struct are through a different self type (e.g., self: Rc<Mystruct>). In this case, we can indicate faux to hold a non-owned version (e.g., Rc<MyStruct>). This is particularly useful if the only methods that return an instance of the struct return a non-owned instance of it.

If this attribute is set, all of the impl blocks tagged with #[methods] must specify the same self_type.

Usage

use std::sync::Arc;

#[faux::create(self_type = "Arc")]
pub struct MyStruct {
    /* private fields */
}

#[faux::methods(self_type = "Arc")]
impl MyStruct {
    pub fn new() -> Arc<Self> {
        /* implementation */
    }

    /* more methods */
}