spec: added raise_subproc_error (#5494)

### Motivation

Add `spec.raise_subproc_error` to have an ability to use
`SpecModifierAlias` to manage the errors. Also this is the first step to
#4351.

Generally in scripts it's good to have RAISE_SUBPROC_ERROR=True to avoid
processing the error for every executed command. But in some cases (e.g.
`![]`) it's needed to avoid raising the error. To more elegant doing
this we can make an ability to create SpecModifier.

### After

```xsh
from xonsh.procs.specs import SpecModifierAlias
class SpecModifierNoErrAlias(SpecModifierAlias):
    def on_modifer_added(self, spec):
        spec.raise_subproc_error = False
aliases['noraise'] = SpecModifierNoErrAlias()

$RAISE_SUBPROC_ERROR = True

if ![noraise git pull]:
    git add --all
```

Cc #5443 

## For community
⬇️ **Please click the 👍 reaction instead of leaving a `+1` or 👍
comment**

---------

Co-authored-by: a <1@1.1>
Co-authored-by: pre-commit-ci[bot] <66853113+pre-commit-ci[bot]@users.noreply.github.com>

news/spec_raise_subproc_error.rst

@@ -0,0 +1,23 @@
+**Added:**
+
+* Added ``spec.raise_subproc_error`` for fine-tuning exceptions via ``SpecModifierAlias`` (#5494).
+
+**Changed:**
+
+* <news item>
+
+**Deprecated:**
+
+* <news item>
+
+**Removed:**
+
+* <news item>
+
+**Fixed:**
+
+* <news item>
+
+**Security:**
+
+* <news item>

tests/procs/test_specs.py

@@ -3,7 +3,7 @@
 import itertools
 import signal
 import sys
-from subprocess import Popen
+from subprocess import CalledProcessError, Popen
 
 import pytest
 
@@ -163,6 +163,51 @@ def test_interrupted_process_returncode(xonsh_session, captured, interactive):
     assert p.proc.returncode == -signal.SIGINT
 
 
+@skip_if_on_windows
+def test_proc_raise_subproc_error(xonsh_session):
+    xonsh_session.env["RAISE_SUBPROC_ERROR"] = False
+
+    specs = cmds_to_specs(cmd := [["ls"]], captured="stdout")
+    specs[-1].raise_subproc_error = True
+    exception = None
+    try:
+        (p := _run_command_pipeline(specs, cmd)).end()
+        assert p.proc.returncode == 0
+    except Exception as e:
+        exception = e
+    assert exception is None
+
+    specs = cmds_to_specs(cmd := [["ls", "nofile"]], captured="stdout")
+    specs[-1].raise_subproc_error = False
+    exception = None
+    try:
+        (p := _run_command_pipeline(specs, cmd)).end()
+        assert p.proc.returncode > 0
+    except Exception as e:
+        exception = e
+    assert exception is None
+
+    specs = cmds_to_specs(cmd := [["ls", "nofile"]], captured="stdout")
+    specs[-1].raise_subproc_error = True
+    exception = None
+    try:
+        (p := _run_command_pipeline(specs, cmd)).end()
+    except Exception as e:
+        assert p.proc.returncode > 0
+        exception = e
+    assert isinstance(exception, CalledProcessError)
+
+    xonsh_session.env["RAISE_SUBPROC_ERROR"] = True
+    specs = cmds_to_specs(cmd := [["ls", "nofile"]], captured="stdout")
+    exception = None
+    try:
+        (p := _run_command_pipeline(specs, cmd)).end()
+    except Exception as e:
+        assert p.proc.returncode > 0
+        exception = e
+    assert isinstance(exception, CalledProcessError)
+
+
 @skip_if_on_windows
 @pytest.mark.parametrize(
     "suspended_pipeline",

xonsh/procs/pipelines.py

@@ -627,9 +627,16 @@ class CommandPipeline:
         spec = self.spec
         rtn = self.returncode
 
-        if rtn is None or rtn == 0 or not XSH.env.get("RAISE_SUBPROC_ERROR"):
+        if rtn is None or rtn == 0:
             return
 
+        raise_subproc_error = spec.raise_subproc_error
+        if callable(raise_subproc_error):
+            raise_subproc_error = raise_subproc_error(spec, self)
+        if raise_subproc_error is False:
+            return
+
+        if raise_subproc_error or XSH.env.get("RAISE_SUBPROC_ERROR", True):
             try:
                 raise subprocess.CalledProcessError(rtn, spec.args, output=self.output)
             finally:

xonsh/procs/specs.py

@@ -421,6 +421,7 @@ class SubprocSpec:
         self.stack = None
         self.spec_modifiers = []  # List of SpecModifierAlias objects that applied to spec.
         self.output_format = XSH.env.get("XONSH_SUBPROC_OUTPUT_FORMAT", "stream_lines")
+        self.raise_subproc_error = None  # Spec-based $RAISE_SUBPROC_ERROR.
 
     def __str__(self):
         s = self.__class__.__name__ + "(" + str(self.cmd) + ", "