ZopeEnvironment

ZTC makes the following assumptions about its environment:

a) The ZopeTestCase package is installed in the Zope "trunk" inside the Testing module, which is SOFTWARE_HOME/Testing/ZopeTestCase. Note that the Testing module itself is used by ZTC (e.g. the default custom_zodb.py, setting up an empty DemoStorage, is the one from Testing).

b) A Products directory exists inside SOFTWARE_HOME and INSTANCE_HOME.

c) The tests (the tests subdirectories) are located either below a SOFTWARE_HOME or INSTANCE_HOME, typically in Products/MyCoolProduct/tests.

d) The weak assumption is that ZTC can just walk up the directory tree from tests, and find a Products directory. This is how INSTANCE_HOME detection works. It regrettably fails on some filesystems when symbolic links are involved; there is a remedy though, read on.

The tricky part is that INSTANCE_HOME has two distinct purposes:

1) INSTANCE_HOME/lib/python must be added to sys.path and INSTANCE_HOME/Products to Products.__path__.

2) INSTANCE_HOME/custom_zodb.py must be used to set up a ZODB.

ZTC attempts to resolve this by detecting an INSTANCE_HOME for 1) but leaving the actual environment variable untouched so 2) works by still pointing into SOFTWARE_HOME/Testing.

As soon as I allow you to set INSTANCE_HOME yourself, I lose the ability to distinguish whether you mean 1) or 2) or both.

Before ZTC 0.6.2 the code assumed "both" and did the magic ZEO dance. This was clearly too surprising.

The behaviour has now changed to 1).

That way, if your setup does not fit c) or you run into the symbolic link problem d), you can solve it by setting INSTANCE_HOME prior to running the tests.

ZEO support ("both") is handled separately, through the new environment variable ZEO_INSTANCE_HOME.