Sort deps when saving to avoid surprising diffs down the road

elm_deps_sync.py

@@ -2,6 +2,7 @@
 from __future__ import print_function
 
 import sys
+from collections import OrderedDict
 import json
 import argparse
 
@@ -41,12 +42,13 @@ def sync_versions(top_level_file, spec_file, quiet=False, dry=False, note_test_d
             test_deps[package_name] = package_version
 
     if note_test_deps:
-        spec['test-dependencies'] = test_deps
+        spec['test-dependencies'] = sorted_deps(test_deps)
 
     if len(messages) > 0 or note_test_deps:
         print('{number} packages changed.'.format(number=len(messages)))
 
         if not dry:
+            spec['dependencies'] = sorted_deps(spec['dependencies'])
             with open(spec_file, 'w') as f:
                 json.dump(spec, f, sort_keys=False, indent=4)
         else:
@@ -58,6 +60,10 @@ def sync_versions(top_level_file, spec_file, quiet=False, dry=False, note_test_d
         print('No changes needed.')
 
 
+def sorted_deps(deps):
+    return OrderedDict(sorted(deps.items()))
+
+
 def main():
 
     parser = argparse.ArgumentParser(description='Sync deps between a parent and a sub')

tests/test_elm_deps_sync.py

@@ -0,0 +1,38 @@
+from collections import OrderedDict
+import json
+
+import pytest
+
+import elm_deps_sync
+
+
+def test_spec_order_is_preserved(tmpdir):
+    top_level_file = tmpdir.join('elm-package.json')
+    spec_file = tmpdir.join('spec-elm-package.json')
+
+    top_level = {
+        'dependencies': OrderedDict([
+            ('NoRedInk/top-3', '1.0.0 <= v <= 1.0.0'),
+            ('NoRedInk/top-1', '1.0.0 <= v <= 1.0.0'),
+            ('NoRedInk/top-2', '1.0.0 <= v <= 1.0.0'),
+        ])
+    }
+    top_level_file.write(json.dumps(top_level))
+
+    spec = {
+        'dependencies': OrderedDict([
+            ('NoRedInk/top-2', '1.0.0 <= v <= 1.0.0'),
+            ('NoRedInk/top-1', '1.0.0 <= v <= 1.0.0'),
+        ])
+    }
+    spec_file.write(json.dumps(spec))
+
+    elm_deps_sync.sync_versions(
+        str(top_level_file),
+        str(spec_file),
+        quiet=False,
+        dry=False,
+        note_test_deps=True)
+
+    new_spec = json.loads(spec_file.read(), object_pairs_hook=OrderedDict)
+    assert new_spec['dependencies'].keys() == ['NoRedInk/top-1', 'NoRedInk/top-2', 'NoRedInk/top-3']