Gost-DOM Fixture

Fixture is a tool to help setup test fixtures¹, i.e., a component in the test suite that places the SUT² in a controlled context.

This is intended for the case when:

• Setting up the SUT is non-trivial
• Multiple tests needs to use the SUT in an identical or similar manner
• Simple init functions tend to litter test code with noise, hiding the essence of the test.

Using Fixture adds some complexity to test through indirection, so be sure you have the problem it solves before using it.

Fixture is inspired by pytest fixtures

Note

The word "fixture" can be confusing in this document, it can refer to :

• This library (always written in as a proper name, Fixture)
• The default type (always written as a code block Fixture).
• The concept of a fixture (always written in the default typography)

I apologize to screen reader users, that may not easily pick up on the typography. I experimented with an alternate name for the library, but I felt "fixture" is the right name for the library, and clarity in the readme file wasn't a good enough reason to rename.

Looking for sponsors.

This project was conceived as part of the Gost-DOM project, a massively ambitious project to build a headless browser in Go for testing Go web applications.

Without financial support for the developement, Gost-DOM is unlikely to become a useful tool.

How it works.

After reading this, turn to Getting started for a code example.

Fixture is based on the following principles.

• A Fixture is a component used to setup a SUT in a test context
• A Fixture can depend on other fixtures.
• Dependent fixtures can be shared by multiple fixtures.
• A Fixture can have initialization/setup code.
• A Fixture can integrate to Go's testing.TB.

When initializing a fixture, Fixture will iterate through the dependencies, it will:

• Check if the value should be touched.
• For nil pointer value
  • If a value of this type has already been created, use the same type.
  • Otherwise, create a new empty value
• Unless an configured value was reused:
  • If the type is a struct (or a pointer to one), iterate all fields of the struct recursively.
  • If the type has a SetTB(testing.TB) method, it will be called.
  • If the type has a Setup() method, add this to a list of setup methods.

The Init function will return the modified fixture, and a value with a Setup() method, passing control to the test when to setup the method.

Be aware

Caution

Fixture doesn't include a cyclic dependency check. If your fixtures have a cyclick dependency, that could possibly result in infinite recursion (resulting in a stack overflow)

Footnotes

1. Fixture is a metaphor from mechanical engineering. A fixture holds a piece in place, e.g., when testing its mechanical properties. For software testing this generally refers to code that places the SUT in a specific context, but some test frameworks use the term to refer to the test or suite itself. ↩

2. System under test. ↩