openhtf 1.5.2

OpenHTF, the open hardware testing framework.

DISCLAIMER: This is not an official Google product.

OpenHTF

The open-source hardware testing framework.

Overview

OpenHTF is a Python library that provides a set of convenient abstractions designed to remove as much boilerplate as possible from hardware test setup and execution, so test engineers can focus primarily on test logic. It aspires to do so in a lightweight and minimalistic fashion. It is general enough to be useful in a variety of hardware testing scenarios, from the lab bench to the manufacturing floor.

Installing OpenHTF

NOTE: We recommend using virtualenv to create an isolated Python environments for your projects, so as to protect system-wide Python packages the OS depends upon. The installation instructions assume you've already created a virtualenv and activated it if you wish to do so.

Option 1: Installing via 'pip' (recommended)

The most straightforward way to get the openhtf Python package into your Python environment is simply to install it via pip. This will install the most recent production release.

pip install openhtf

Option 2: Installing from Source

If you want to install from source instead (for example, if you want some new feature that hasn't made it to the production release yet), you can download the source code via git or other means, and install the openhtf package into your Python environment using the standard setup.py script.

python setup.py install

Using OpenHTF

The fastest way to get started is to take a look in the examples/ directory, where you'll find sample test scripts and plugs. In addition, many of OpenHTF's modules are fairly well documented inline through the use of docstrings.

Note: some of the examples/ require protocol buffer code to be generated via python setup.py build command. This requires protocol buffer compiler library to be installed (additional instructions).

Nomenclature

OpenHTF uses certain nomenclature internally for several of its core concepts. Some of the more important terms are listed here for clarity.

DUT (Device Under Test)

DUT refers to an individual piece of hardware being evaluated, exercised, or tested.

Test

The top-level abstraction that OpenHTF deals with is the test. A test is just a series of steps performed on/with a DUT, usually along with some data-gathering or measurement steps. In the OpenHTF paradigm, tests are expressed as regular Python programs (.py files) that import and instantiate the 'Test' class from the openhtf module. That way test code is as straightforward as possible to read and write. This also provides for the flexibility to do anything in a test that can normally be done in Python. Superficially, what distinguishes an OpenHTF test from any other Python program is that the OpenHTF test imports the openhtf package, instantiates the Test class, and calls its Execute() function. From there, OpenHTF manages the setup, execution, and teardown of the test, keeps track of anything gathered, and provides a pass/fail result.

At times it may be necessary to disambiguate between different common readings of the word test. In such scenarios we use the following more precise terms:

• test run - A single start-to-finish execution of a specific test.
• test recipe - A test definition that may be executed multiple times, each time as a distinct test run.
• test script - A .py file that contains a test recipe.

Station

Stations capture the notion that a given test ran at some point and may run again. It loosely reflects the idea of physical test stations that process multiple DUTs over time. OpenHTF writes a breadcrumb to the filesystem (in a directory that can be set using the --rundir flag) each time a test runs, and all tests that have the same name are considered to be of the same station. This way the web frontend can display a consolidated list of known tests as a list of stations.

Phase

OpenHTF tests are broken down into logical blocks called phases. Phases are no more than normal Python callables (usually functions) combined with the needed metadata. Writing an OpenHTF test is just a matter of writing a bunch of phase functions and specifying the order in which they should be executed.

Measurement

OpenHTF gathers data about a DUT in the form of measurements. Usually, measurements are declared along with a specification that describes what constitutes a "passing" value. If OpenHTF finishes the test run and one or more measurements were out of that spec, the result of the whole test run will be considered a fail.

Attachment

Sometimes may want to capture additional data that is more complex or free-form than a measurement. An attachment can link arbitrary binary data to a test record, along with an optional MIME type.

Plug

The essence of an OpenHTF test is to interact with a DUT to exercise it in various ways and observe the result. Sometimes this is done by communicating directly with the DUT, and other times it's done by communicating with a piece of test equipment to which the DUT is attached in some way. A plug is a piece of code written to enable OpenHTF to interact with a particular type of hardware, whether that be a DUT itself or a piece of test equipment. OpenHTF comes packaged with a growing collection of useful plugs, but supports the creation of custom plugs as well.