Breathe's tests fail for sphinx >= 2.2.2 with "Domain 'c' is not registered"

[D4N]

A recent update of Sphinx to 2.2.2 in Fedora Rawhide broke the unit test of breathe. Now 4 tests are failing with:

======================================================================
ERROR: test_renderer.test_render_c_typedef
----------------------------------------------------------------------
Traceback (most recent call last):
  File "/home/dan/packages/github.com/michaeljones/breathe/.env3/lib64/python3.7/site-packages/sphinx/environment/__init__.py", line 515, in get_domain
    return self.domains[domainname]
KeyError: 'c'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/dan/packages/github.com/michaeljones/breathe/.env3/lib64/python3.7/site-packages/nose/case.py", line 198, in runTest
    self.test(*self.arg)
  File "/home/dan/packages/github.com/michaeljones/breathe/tests/test_renderer.py", line 286, in test_render_c_typedef
    signature = find_node(render(member_def, domain='c'), 'desc_signature')
  File "/home/dan/packages/github.com/michaeljones/breathe/tests/test_renderer.py", line 257, in render
    return renderer.render(member_def)
  File "/home/dan/packages/github.com/michaeljones/breathe/breathe/renderer/sphinxrenderer.py", line 1308, in render
    result = method(self, node)
  File "/home/dan/packages/github.com/michaeljones/breathe/breathe/renderer/sphinxrenderer.py", line 1249, in dispatch_memberdef
    return self.visit_typedef(node)
  File "/home/dan/packages/github.com/michaeljones/breathe/breathe/renderer/sphinxrenderer.py", line 1092, in visit_typedef
    update_signature=update_signature)
  File "/home/dan/packages/github.com/michaeljones/breathe/breathe/renderer/sphinxrenderer.py", line 412, in render_declaration
    nodes = self.run_domain_directive(obj_type, [declaration.replace('\n', ' ')])
  File "/home/dan/packages/github.com/michaeljones/breathe/breathe/renderer/sphinxrenderer.py", line 357, in run_domain_directive
    nodes = domain_directive.run()
  File "/home/dan/packages/github.com/michaeljones/breathe/.env3/lib64/python3.7/site-packages/sphinx/directives/__init__.py", line 187, in run
    self.add_target_and_index(name, sig, signode)
  File "/home/dan/packages/github.com/michaeljones/breathe/.env3/lib64/python3.7/site-packages/sphinx/domains/c.py", line 209, in add_target_and_index
    domain = cast(CDomain, self.env.get_domain('c'))
  File "/home/dan/packages/github.com/michaeljones/breathe/.env3/lib64/python3.7/site-packages/sphinx/environment/__init__.py", line 517, in get_domain
    raise ExtensionError(__('Domain %r is not registered') % domainname)
sphinx.errors.ExtensionError: Domain 'c' is not registered

The other failing tests (with a similarly looking backtrace) are:

• test_renderer.test_render_c_function_typedef
• test_renderer.test_render_define_initializer
• test_renderer.test_render_define_no_initializer

Unfortunately, I am not too proficient with breathe and couldn't find a solution of this issue. My guess would be that the unit tests are not registering the C domain, but I am too unfamiliar with sphinx' API to figure out how to properly register it.

[t-b]

I think breathe needs to call the setup routine at https://github.com/sphinx-doc/sphinx/blob/1ef607b4ccabe3410d8aca68a7dbd796e14d578d/sphinx/environment/__init__.py#L199 before trying to access the domains. But that is just a guess.

[vermeeren]

Breathe v4.14.1 is now released with the fix.