1467225 - Test suite fails with extra whitespace in test output

Status: RESOLVED INVALID

(Developer Services :: Mercurial: hg.mozilla.org, defect)

Description

[Māris Fogels [:mars] (please needinfo)]

Some tests in the hgext/hgmo/tests/ directory fail because the output of json.tool contains trailing whitespace.  It appears to be a known side-effect of the Python json.tool module.  I observed this running Python 2.7.15.

This whitespace gotcha has been documented in the Python 2.7.15 module docs.  See the Note about separator() in https://docs.python.org/2/library/json.html#basic-usage.

Steps to reproduce:

1. Copy an output produced by json.tool from a test file into a new file. e.g. hgext/hgmo/tests/test-json-changeset.t
2. 'cat -A test.json' produces the expected output
3. 'python -m json.tool test.json | cat -A' shows extra trailing whitespace.


Example failure:

./run-tests hgext/hgmo/tests/test-json-extradata.t 2>&1 | cat -A
Will run 15 non-Docker tests concurrently$
Running non-Docker Mercurial tests$
$
--- /home/mars/work/version-control-tools/hgext/hgmo/tests/test-json-extradata.t$
+++ /home/mars/work/version-control-tools/hgext/hgmo/tests/test-json-extradata.t.err$
@@ -48,28 +48,28 @@$
 $
   $ python -m json.tool < body$
   {$
-      "backedoutby": "",$
-      "bookmarks": [],$
-      "branch": "default",$
+      "backedoutby": "", $
+      "bookmarks": [], $
+      "branch": "default", $
       "date": [$
-          0.0,$
+          0.0, $
           0$
-      ],$
-      "desc": "NO BUG",$
-      "landingsystem": "wobble",$
-      "node": "c761ad6d27c96f72f7e4637789e967c3f9730255",$
+      ], $
+      "desc": "NO BUG", $
+      "landingsystem": "wobble", $
+      "node": "40e31a84e3dcf059c2e33d5a266edc6bad3b81ed", $
       "parents": [$
-          "ef0e7ae3b607356f580e6d7671abea63db849cc2"$
-      ],$
-      "phase": "public",$
+          "afa8227ab48e5f3c749fb59f2e886cb487594cf2"$
+      ], $
+      "phase": "public", $
       "pushdate": [$
-          \d+, (re)$
+          1528302892, $
           \d+ (re)$
-      ],$
-      "pushid": 3,$
-      "pushuser": "hguser",$
+      ], $
+      "pushid": 3, $
+      "pushuser": "hguser", $
       "tags": [$
           "tip"$
-      ],$
+      ], $
       "user": "test"$
   }$
$
ERROR: test-json-extradata.t output changed$
!$
Failed test-json-extradata.t: output changed$
# Ran 1 tests, 0 skipped, 1 failed.$

Comment 1

[Māris Fogels [:mars] (please needinfo)]

There was definitely a change in the standard library json/tool.py file at some point.

pycharm-2016 json/tool.py:
    ...
    with outfile:
        json.dump(obj, outfile, sort_keys=True,
                  indent=4, separators=(',', ': '))
        outfile.write('\n')

pyenv python-2.7 json/tool.py:
    ...
    json.dump(obj, outfile, sort_keys=True, indent=4)  # uses default separator of ', '
    outfile.write('\n')

Comment 2

[Māris Fogels [:mars] (please needinfo)]

I had an incorrectly configured environment and was using the wrong Python 2.7 interpreter.  I rebuilt my environment on top of Python 2.7.14 and the test suite passes.