Merge pull request #2998 from bskinn/venv-prompt

Implement VIRTUAL_ENV_PROMPT and VIRTUAL_ENV_DISABLE_PROMPT

docs/tutorial.rst

@@ -1422,7 +1422,9 @@ By default, the following variables are available for use:
     ``/path/to/xonsh``.
   * ``cwd_base``: The basename of the current working directory, e.g. ``xonsh`` in
     ``/path/to/xonsh``.
-  * ``env_name``: The name of active virtual environment, if any.
+  * ``env_name``: The name of active virtual environment, if any. The rendering
+    of this variable is affected by the ``$VIRTUAL_ENV_PROMPT`` and
+    ``$VIRTUAL_ENV_DISABLE_PROMPT`` environment variables; see below.
   * ``env_prefix``: The prefix characters if there is an active virtual environment,
     defaults to ``"("``.
   * ``env_postfix``: The postfix characters if there is an active virtual environment,
@@ -1441,6 +1443,33 @@ By default, the following variables are available for use:
   * ``gitstatus``: Informative git status, like ``[master|MERGING|+1…2]``, you
     may use `$XONSH_GITSTATUS_* <envvars.html>`_ to customize the styling.
 
+xonsh obeys the ``$VIRTUAL_ENV_DISABLE_PROMPT`` environment variable
+`as defined by virtualenv <https://virtualenv.pypa.io/en/latest/reference/
+#envvar-VIRTUAL_ENV_DISABLE_PROMPT>`__. If this variable is truthy, xonsh
+will *always* substitute an empty string for ``{env_name}``. Note that unlike
+with other shells, ``$VIRTUAL_ENV_DISABLE_PROMPT`` takes effect *immediately*
+after being set---it is not necessary to re-activate the environment.
+
+xonsh also allows for an explicit override of the rendering of ``{env_name}``,
+via the ``$VIRTUAL_ENV_PROMPT`` environment variable. If this variable is
+defined and has any value other than ``None``, ``{env_name}`` will *always*
+render as ``str($VIRTUAL_ENV_PROMPT)`` when an environment is activated.
+It will still render as an empty string when no environment is active.
+``$VIRTUAL_ENV_PROMPT`` is overridden by ``$VIRTUAL_ENV_DISABLE_PROMPT``.
+
+For example:
+
+.. code-block:: xonshcon
+
+    >>> $PROMPT = '{env_name}>>> '
+    >>> source env/bin/activate.xsh
+    (env) >>> $VIRTUAL_ENV_PROMPT = '~~ACTIVE~~ '
+    ~~ACTIVE~~ >>> $VIRTUAL_ENV_DISABLE_PROMPT = 1
+    >>> del $VIRTUAL_ENV_PROMPT
+    >>> del $VIRTUAL_ENV_DISABLE_PROMPT
+    (env) >>>
+
+
 You can also color your prompt easily by inserting keywords such as ``{GREEN}``
 or ``{BOLD_BLUE}``.  Colors have the form shown below:
 

news/envprepost.rst

@@ -6,7 +6,7 @@
 **Changed:**
 
 * ``env_name`` prompt field now looks up the pre- and post-fix characters,
-  rather than relying on hard-coded values/
+  rather than relying on hard-coded values.
 
 **Deprecated:**
 

news/prompt-env-vars.rst

@@ -0,0 +1,29 @@
+**Added:**
+
+* Rendering of ``{env_name}`` in ``$PROMPT`` is now suppressed if
+  the ``$VIRTUAL_ENV_DISABLE_PROMPT`` environment variable is
+  defined and truthy.
+* Rendering of ``{env_name}`` in ``$PROMPT`` is now overridden by
+  the value of ``str($VIRTUAL_ENV_PROMPT)`` if that environment variable
+  is defined and ``not None``. ``$VIRTUAL_ENV_DISABLE_PROMPT`` takes precedence
+  over ``$VIRTUAL_ENV_PROMPT``.
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>

tests/test_prompt.py

@@ -6,7 +6,7 @@ from unittest.mock import Mock
 import pytest
 
 from xonsh.environ import Env
-from xonsh.prompt.base import PromptFormatter
+from xonsh.prompt.base import PromptFormatter, PROMPT_FIELDS
 from xonsh.prompt import vc
 
 from tools import skip_if_py34, DummyEnv
@@ -17,6 +17,11 @@ def formatter(xonsh_builtins):
     return PromptFormatter()
 
 
+@pytest.fixture
+def live_fields():
+    return PROMPT_FIELDS
+
+
 @pytest.mark.parametrize(
     "fields", [{"a_string": "cat", "none": (lambda: None), "f": (lambda: "wakka")}]
 )
@@ -97,6 +102,80 @@ def test_format_prompt_with_func_that_raises(formatter, capsys, xonsh_builtins):
     assert "prompt: error" in err
 
 
+def test_format_prompt_with_no_env(formatter, xonsh_builtins, live_fields):
+    xonsh_builtins.__xonsh__.shell.prompt_formatter = formatter
+
+    env = Env()
+    env.pop('VIRTUAL_ENV', None)        # For virtualenv
+    env.pop('CONDA_DEFAULT_ENV', None)  # For conda/CircleCI
+    xonsh_builtins.__xonsh__.env = env
+
+    assert formatter('{env_name}', fields=live_fields) == ''
+
+
+@pytest.mark.parametrize('envname', ['env', 'foo', 'bar'])
+def test_format_prompt_with_various_envs(formatter, xonsh_builtins, live_fields, envname):
+    xonsh_builtins.__xonsh__.shell.prompt_formatter = formatter
+
+    env = Env(VIRTUAL_ENV=envname)
+    xonsh_builtins.__xonsh__.env = env
+
+    exp = live_fields['env_prefix'] + envname + live_fields['env_postfix']
+    assert formatter('{env_name}', fields=live_fields) == exp
+
+
+@pytest.mark.parametrize('pre', ['(', '[[', '', '   '])
+@pytest.mark.parametrize('post', [')', ']]', '', '   '])
+def test_format_prompt_with_various_prepost(
+    formatter,
+    xonsh_builtins,
+    live_fields,
+    pre,
+    post,
+):
+    xonsh_builtins.__xonsh__.shell.prompt_formatter = formatter
+
+    env = Env(VIRTUAL_ENV='env')
+    xonsh_builtins.__xonsh__.env = env
+
+    live_fields.update({'env_prefix': pre, 'env_postfix': post})
+
+    exp = pre + 'env' + post
+    assert formatter('{env_name}', fields=live_fields) == exp
+
+
+def test_noenv_with_disable_set(formatter, xonsh_builtins, live_fields):
+    xonsh_builtins.__xonsh__.shell.prompt_formatter = formatter
+
+    env = Env(VIRTUAL_ENV='env', VIRTUAL_ENV_DISABLE_PROMPT=1)
+    xonsh_builtins.__xonsh__.env = env
+
+    exp = ''
+    assert formatter('{env_name}', fields=live_fields) == exp
+
+
+@pytest.mark.parametrize('disable', [0, 1])
+def test_custom_env_overrides_default(
+    formatter,
+    xonsh_builtins,
+    live_fields,
+    disable,
+):
+    xonsh_builtins.__xonsh__.shell.prompt_formatter = formatter
+
+    prompt = '!venv active! '
+
+    env = Env(
+        VIRTUAL_ENV='env',
+        VIRTUAL_ENV_PROMPT=prompt,
+        VIRTUAL_ENV_DISABLE_PROMPT=disable,
+    )
+    xonsh_builtins.__xonsh__.env = env
+
+    exp = '' if disable else prompt
+    assert formatter('{env_name}', fields=live_fields) == exp
+
+
 def test_promptformatter_cache(formatter):
     spam = Mock()
     template = "{spam} and {spam}"

xonsh/built_ins.py

@@ -13,7 +13,6 @@ import shlex
 import signal
 import atexit
 import pathlib
-import platform
 import inspect
 import warnings
 import builtins

xonsh/prompt/env.py

@@ -23,13 +23,21 @@ def env_name():
     ``{env_prefix}`` and ``{env_postfix}`` fields.
     """
     env_name = find_env_name()
-    if not env_name:
-        # no environment, just return
+    if (
+        builtins.__xonsh__.env.get("VIRTUAL_ENV_DISABLE_PROMPT")
+        or not env_name
+    ):
+        # env name prompt printing disabled, or no environment; just return
         return
-    pf = builtins.__xonsh__.shell.prompt_formatter
-    pre = pf._get_field_value("env_prefix")
-    post = pf._get_field_value("env_postfix")
-    return pre + env_name + post
+
+    venv_prompt = builtins.__xonsh__.env.get("VIRTUAL_ENV_PROMPT")
+    if venv_prompt is not None:
+        return venv_prompt
+    else:
+        pf = builtins.__xonsh__.shell.prompt_formatter
+        pre = pf._get_field_value("env_prefix")
+        post = pf._get_field_value("env_postfix")
+        return pre + env_name + post
 
 
 def vte_new_tab_cwd():