view tests/README @ 990:5007e0bdeed2

Fix long-standing excessive file merges

Since switching to the multihead approach, we've been creating
excessive file-level merges where files are marked as merged with
their ancestors.

This explicitly checks at commit time whether the two parent versions
are linearly related, and if so, reduces the file check-in to a
non-merge. Then the file is compared against the remaining parent,
and, if equal, skips check-in of that file (as it's not changed).

Since we're not checking in all files that were different between
versions, we no longer need to mark so many files for merge. This
removes most of the 'm' state marking as well.

Finally, it is possible to do a tree-level merge with no file-level
changes. This will happen if one user changes file A and another
changes file B. Thus, if we have have two parents, we allow commit to
proceed even if there are no file-level changes.

A simple testing framework

To run the tests, do:

cd tests/
./run-tests

This finds all scripts in the test directory named test-* and executes
them. The scripts can be either shell scripts or Python. Each test is
run in a temporary directory that is removed when the test is complete.

A test-<x> succeeds if the script returns success and its output
matches test-<x>.out. If the new output doesn't match, it is stored in
test-<x>.err.

There are some tricky points here that you should be aware of when
writing tests:

- hg commit and hg up -m want user interaction

  for commit use -m "text"
  for hg up -m, set HGMERGE to something noninteractive (like true or merge)

- changeset hashes will change based on user and date which make
  things like hg history output change

  use commit -m "test" -u test -d "0 0"

- diff will show the current time

  use hg diff | sed "s/\(\(---\|+++\) [a-zA-Z0-9_/.-]*\).*/\1/" to strip
  dates