Added support for suppressing spinner when not on a TTY.

Signed-off-by: Andreas Maier <andras.r.maier@gmx.de>

Author: Andreas Maier

.travis.yml

@@ -8,6 +8,7 @@ notifications:
   - yoav@yoavram.com
 install:
 - pip install click
+- pip install six
 - python setup.py install
 script: py.test
 deploy:

click_spinner/__init__.py

@@ -7,18 +7,21 @@
 class Spinner(object):
     spinner_cycle = itertools.cycle(['-', '/', '|', '\\'])
 
-    def __init__(self):
+    def __init__(self, force=False):
+        self._force = force
         self.stop_running = None
         self.spin_thread = None
 
     def start(self):
-        self.stop_running = threading.Event()
-        self.spin_thread = threading.Thread(target=self.init_spin)
-        self.spin_thread.start()
+        if sys.stdout.isatty() or self._force:
+            self.stop_running = threading.Event()
+            self.spin_thread = threading.Thread(target=self.init_spin)
+            self.spin_thread.start()
 
     def stop(self):
-        self.stop_running.set()
-        self.spin_thread.join()
+        if self.spin_thread:
+            self.stop_running.set()
+            self.spin_thread.join()
 
     def init_spin(self):
         while not self.stop_running.is_set():
@@ -34,9 +37,16 @@ def __exit__(self, exc_type, exc_val, exc_tb):
         self.stop()
 
 
-def spinner():
+def spinner(force=False):
     """This function creates a context manager that is used to display a
-    spinner as long as the context has not exited.
+    spinner on stdout as long as the context has not exited.
+
+    The spinner is created only if stdout is not redirected, or if the spinner
+    is forced using the `force` parameter.
+
+    Parameters:
+
+      force (bool): Force creation of spinner even when stdout is redirected.
 
     Example usage::
 
@@ -45,7 +55,7 @@ def spinner():
             do_something_else()
 
     """
-    return Spinner()
+    return Spinner(force)
 
 
 from ._version import get_versions

setup.py

@@ -18,8 +18,9 @@
     description='Spinner for Click',
     extras_require={
         'test': [
-            'click'
+            'click',
             'pytest',
+            'six',
         ]
     }
 )

tests/test_spinner.py

@@ -1,3 +1,8 @@
+import sys
+import os
+import time
+import tempfile
+from six import StringIO
 import click
 from click.testing import CliRunner
 
@@ -33,3 +38,43 @@ def cli():
     result = runner.invoke(cli, [])
     assert result.exception is None
 
+
+def test_spinner_redirect():
+    @click.command()
+    def cli():
+       stdout_io = StringIO()
+       saved_stdout = sys.stdout
+       sys.stdout = stdout_io  # redirect stdout to a string buffer
+       spinner = click_spinner.Spinner()
+       spinner.start()
+       time.sleep(1)  # allow time for a few spins
+       spinner.stop()
+       sys.stdout = saved_stdout
+       stdout_io.flush()
+       stdout_str = stdout_io.getvalue()
+       assert len(stdout_str) == 0
+
+    runner = CliRunner()
+    result = runner.invoke(cli, [])
+    assert result.exception is None
+
+
+def test_spinner_redirect_force():
+    @click.command()
+    def cli():
+       stdout_io = StringIO()
+       saved_stdout = sys.stdout
+       sys.stdout = stdout_io  # redirect stdout to a string buffer
+       spinner = click_spinner.Spinner(force=True)
+       spinner.start()
+       time.sleep(1)  # allow time for a few spins
+       spinner.stop()
+       sys.stdout = saved_stdout
+       stdout_io.flush()
+       stdout_str = stdout_io.getvalue()
+       assert len(stdout_str) > 0
+
+    runner = CliRunner()
+    result = runner.invoke(cli, [])
+    assert result.exception is None
+