new NoArgsIsHelpError for displaying default help

Author: davidism

CHANGES.rst

@@ -73,6 +73,9 @@ Unreleased
 -   Required arguments with the ``Choice`` type show the choices in
     curly braces to indicate that one is required (``{a|b|c}``).
     :issue:`1272`
+-   If help is shown because ``no_args_is_help`` is enabled (default on
+    for groups, off for commands), the exit code is 1 instead of 0.
+    :issue:`1489`
 
 
 Version 7.1.2

src/click/core.py

@@ -13,6 +13,7 @@
 from .exceptions import ClickException
 from .exceptions import Exit
 from .exceptions import MissingParameter
+from .exceptions import NoArgsIsHelpError
 from .exceptions import UsageError
 from .formatting import HelpFormatter
 from .formatting import join_options
@@ -1135,8 +1136,7 @@ def format_epilog(self, ctx, formatter):
 
     def parse_args(self, ctx, args):
         if not args and self.no_args_is_help and not ctx.resilient_parsing:
-            echo(ctx.get_help(), color=ctx.color)
-            ctx.exit()
+            raise NoArgsIsHelpError(ctx)
 
         parser = self.make_parser(ctx)
         opts, args, param_order = parser.parse_args(args=args)
@@ -1303,8 +1303,7 @@ def format_commands(self, ctx, formatter):
 
     def parse_args(self, ctx, args):
         if not args and self.no_args_is_help and not ctx.resilient_parsing:
-            echo(ctx.get_help(), color=ctx.color)
-            ctx.exit(code=1)
+            raise NoArgsIsHelpError(ctx)
 
         rest = super().parse_args(ctx, args)
 

src/click/exceptions.py

@@ -199,6 +199,14 @@ class BadArgumentUsage(UsageError):
     """
 
 
+class NoArgsIsHelpError(UsageError):
+    def __init__(self, ctx):
+        super().__init__(ctx.get_help(), ctx=ctx)
+
+    def show(self, file=None):
+        echo(self.format_message(), file=file, err=True, color=self.ctx.color)
+
+
 class FileError(ClickException):
     """Raised if a file cannot be opened."""
 

tests/test_commands.py

@@ -71,13 +71,9 @@ def long():
     )
 
 
-def test_no_args_is_help(runner):
-    @click.command(no_args_is_help=True)
-    def cli():
-        pass
-
-    result = runner.invoke(cli, [])
-    assert result.exit_code == 0
+def test_command_no_args_is_help(runner):
+    result = runner.invoke(click.Command("test", no_args_is_help=True))
+    assert result.exit_code == 2
     assert "Show this message and exit." in result.output
 
 
@@ -107,8 +103,8 @@ def cli(obj):
     def move():
         click.echo("move")
 
-    result = runner.invoke(cli, [])
-    assert result.exit_code == 0
+    result = runner.invoke(cli)
+    assert result.exit_code == 2
     assert "Show this message and exit." in result.output
 
     result = runner.invoke(cli, ["obj1"])