cocotb-wrapper

cocotb-wrapper provides a wrapper class, called Testbench, that facilitates the use of cocotb.test(). Additionally, this module also contains a wrapper around cocotbext-axi.

Documentation

A little more detailed documentation is available here.

Writing tests using Testbench

First, import the wrapper module with

import cocotb_wrapper as ctw

Writing tests with the Testbench class is a lot less verbose. First, we create a new Testbench object by providing some basic information.

TB = ctw.Testbench("adder", clk="clk_i", rst="rst_ni", reset_active_level=0)

We provided the main clock signal and the main reset signal and its properties (i.e. active high or active low).

Usually, our component requires some setup and teardown procedure, that is required before each test we want to perform. A register and teardown function can be registered using the register_setup and register_teardown decorators.

@TB.register_setup()
async def setup(dut):
  TB.start_clk(dut, period=2, units="ns")
  # Do some initialization
  await TB.reset(dut, time=2, unit="ns")

@TB.register_teardown()
async def teardown(dut):
  # Do some teardown
  await TB.reset(dut, time=2, unit="ns")

The setup and teardown function will be called before and after every registered test. Additionally, the Testbench class provides the start_clk and reset method to start the clock and reset the DUT. Additionaly, clocks and resets have to be driven manually. If no setup or teardown functions are registered, the default ones are executed, which are the ones showed above.

Finally, we can register tests with

@TB.register_test()
async def test_add(dut):
  # Do some stuff
  assert # Some condition

Now when we call the registered tests, every test will execute:

1. the registered setup function
2. the registered test function
3. the registered teardown function

until all the registered tests have been executed. An additional test_id signal (preferrably with the type integer) within the DUT is set to the test ID number. This allows to distinguish tests more easily within the generated wave files, since all the tests are sequentially in one file.