Update sync to return non-zero exit code on dry run

piptools/sync.py

@@ -158,10 +158,12 @@ def sync(
  """
  Install and uninstalls the given sets of modules.
  """
+ exit_code = 0
+
  if not to_uninstall and not to_install:
  if verbose:
  click.echo("Everything up-to-date")
- return 0
+ return exit_code
 
  pip_flags = []
  if not verbose:
@@ -181,8 +183,11 @@ def sync(
  for ireq in sorted(to_install, key=key_from_ireq):
  click.echo(" {}".format(format_requirement(ireq)))
 
+ exit_code = 1
+
  if ask and click.confirm("Would you like to proceed with these changes?"):
  dry_run = False
+ exit_code = 0
 
  if not dry_run:
  if to_uninstall:
@@ -215,4 +220,4 @@ def sync(
  finally:
  os.unlink(tmp_req_file.name)
 
- return 0
+ return exit_code

tests/test_cli_sync.py

@@ -120,7 +120,7 @@ def test_merge_error(req_lines, should_raise, runner):
  assert out.exit_code == 2
  assert "Incompatible requirements found" in out.stderr
  else:
- assert out.exit_code == 0
+ assert out.exit_code == 2
 
 
 @pytest.mark.parametrize(
@@ -231,3 +231,15 @@ def test_sync_ask_accepted(check_call, runner):
  runner.invoke(cli, ["--ask", "--dry-run"], input="y\n")
 
  assert check_call.call_count == 2
+
+
+def test_sync_dry_run_returns_non_zero_exit_code(runner):
+ """
+ Make sure non-zero exit code is returned when --dry-run is given.
+ """
+ with open("requirements.txt", "w") as req_in:
+ req_in.write("small-fake-a==1.10.0")
+
+ out = runner.invoke(cli, ["--dry-run"])
+
+ assert out.exit_code == 1