Mock Graphs for Modular Node Development

Developing a node can be difficult when its inputs are generated as part of a larger flow and you are not yet sure what the commands should be. In this situation, it may not make sense to hook a partially developed node into a full flow to debug the issues. Instead, you can tell mflowgen to mock up a graph where you can provide inputs and test the node in isolation.

The mock-up contains the “design-under-test” node and a “mock-push” node that automatically provides placeholder outputs matching your node’s inputs. For example, the “synopsys-dc-synthesis” node in its mock-up graph would look like this:

You could make sure your node works by spinning in a normal mflowgen environment with full access to normal build targets (e.g., make status). You would provide inputs and iterate on developing your node. You could test the commands, the inputs and outputs, the preconditions and postconditions, and the parameters before connecting it in a larger flow.

As an example, say we are developing and testing a new node “test” that simply reads a file (i.e, “input-foo”) and generates a file (i.e, “output-bar”). Its node configuration file looks like this:

# test/configure.yml

name: test

inputs:
  - input-foo

commands:
  - mkdir -p outputs
  - cat inputs/input-foo > outputs/output-bar

outputs:
  - output-bar

You can tell mflowgen to mock up a graph for this node:

% ls
test

% mkdir build && cd build
% mflowgen mock init --path ../test

The status and information reflects the tiny mock-up graph:

% make status

  Status:

   - build -> 0   : mock-push
   - build -> 1   : test

% make info-1

     _                  _
    | |_    ___   ___  | |_
    | __|  / _ \ / __| | __|
    | |_  |  __/ \__ \ | |_
     \__|  \___| |___/  \__|



              + 0-mock-push
              + input-foo
              |
              V
        +------------+
        | input-foo  |
        +------------+
        |            |
        |   1-test   |
        |            |
        +------------+
        | output-bar |
        +------------+

Running the “make graph” target would generate this graph:

The mock files in “mock-push/outputs” can be replaced with real files. You could then clean and re-run your node as you develop. Remember to pull your changes back into the source copy of your node.