diff tests/test-run-tests.t @ 32998:8dc62c97a665

run-tests: do not prompt changes (-i) if a race condition is detected

The race condition is like:

  1. run-tests.py reads test-a.t as reference output, content A
  2. run-tests.py runs the test (which could be content B, another race
     condition fixed by the next patch, but assume it's content A here)
  3. something changes test-a.t to content C
  4. run-tests.py compares test output (content D) with content A
  5. with "-i", run-tests.py prompts diff(A, D), while the file has content
     C instead of A at this time

This patch detects the above case and tell the user to rerun the test if
they want to apply test changes.

--- a/tests/test-run-tests.t	Tue Jun 20 23:22:38 2017 -0700
+++ b/tests/test-run-tests.t	Wed Jun 21 01:05:20 2017 -0700
@@ -641,6 +641,33 @@
     $ echo 'saved backup bundle to $TESTTMP/foo.hg'
     saved backup bundle to $TESTTMP/*.hg (glob)<
 
+Race condition - test file was modified when test is running
+
+  $ TESTRACEDIR=`pwd`
+  $ export TESTRACEDIR
+  $ cat > test-race.t <<EOF
+  >   $ echo 1
+  >   $ echo "# a new line" >> $TESTRACEDIR/test-race.t
+  > EOF
+
+  $ rt -i test-race.t
+  
+  --- $TESTTMP/test-race.t
+  +++ $TESTTMP/test-race.t.err
+  @@ -1,2 +1,3 @@
+     $ echo 1
+  +  1
+     $ echo "# a new line" >> $TESTTMP/test-race.t
+  Reference output has changed (run again to prompt changes)
+  ERROR: test-race.t output changed
+  !
+  Failed test-race.t: output changed
+  # Ran 1 tests, 0 skipped, 1 failed.
+  python hash seed: * (glob)
+  [1]
+
+  $ rm test-race.t
+
 (reinstall)
   $ mv backup test-failure.t