Mercurial contains a simple regression test framework that allows both Python unit tests and shell-script driven regression tests.

Running the test suite

To run the tests, do:

$ make tests
cd tests && ./run-tests
Ran 44 tests, 0 failed.

This finds all scripts in the tests/ 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.

You can also run tests individually:

$ cd tests/
$ ./run-tests test-pull test-undo
Ran 2 tests, 0 failed.

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.

Writing a shell script test

Creating a regression test is easy. Simply create a shell script that executes the necessary commands to exercise Mercurial.

Here's an example:

hg init
touch a
hg add a
hg commit -m "Added a" -d "0 0"

touch main
hg add main
hg commit -m "Added main" -d "0 0"
hg checkout 0

echo Main should be gone

Then run your test:

$ ./run-tests test-example
test-example generated unexpected output:
Main should be gone

Ran 1 tests, 1 failed.

Double-check your script's output, then save the output so that future runs can check for the expected output:

$ mv test-example.err test-example.out
$ ./run-tests test-example
Ran 1 tests, 0 failed.

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

cat <<'EOF' > merge
echo merging for `basename $1`
chmod +x merge

env HGMERGE=./merge hg update -m 1

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

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

Writing a Python unit test

A unit test operates much like a regression test, but is written in Python. Here's an example:

   1 #!/usr/bin/env python
   3 import sys
   4 from mercurial import bdiff, mpatch
   6 def test1(a, b):
   7     d = bdiff.bdiff(a, b)
   8     c = a
   9     if d:
  10         c = mpatch.patches(a, [d])
  11     if c != b:
  12         print "***", `a`, `b`
  13         print "bad:"
  14         print `c`[:200]
  15         print `d`
  17 def test(a, b):
  18     print "***", `a`, `b`
  19     test1(a, b)
  20     test1(b, a)
  22 test("a\nc\n\n\n\n", "a\nb\n\n\n")
  23 test("a\nb\nc\n", "a\nc\n")
  24 test("", "")
  25 test("a\nb\nc", "a\nb\nc")
  26 test("a\nb\nc\nd\n", "a\nd\n")
  27 test("a\nb\nc\nd\n", "a\nc\ne\n")
  28 test("a\nb\nc\n", "a\nc\n")
  29 test("a\n", "c\na\nb\n")
  30 test("a\n", "")
  31 test("a\n", "b\nc\n")
  32 test("a\n", "c\na\n")
  33 test("", "adjfkjdjksdhfksj")
  34 test("", "ab")
  35 test("", "abc")
  36 test("a", "a")
  37 test("ab", "ab")
  38 test("abc", "abc")
  39 test("a\n", "a\n")
  40 test("a\nb", "a\nb")
  42 print "done"