exit code retrieval: more robust logic

bash_kernel/exit_code_checker.py

@@ -0,0 +1,12 @@
+import re
+
+exit_code_format = "BASHKERNEL_RETCODE<<<{}>>>"
+exit_code_re = re.compile(exit_code_format.format("([0-9]+)"))
+exit_code_printf_format = exit_code_format.format("%d")
+exit_code_command_checker = f'{{ printf "{exit_code_printf_format}" $?; }} 2>/dev/null'
+
+
+def get_last_exit_code(bashwrapper):
+    output = bashwrapper.run_command(exit_code_command_checker)
+    matches = exit_code_re.findall(output)
+    return int(matches[0])

bash_kernel/kernel.py

@@ -16,6 +16,7 @@
 version_pat = re.compile(r'version (\d+(\.\d+)+)')
 
 from .display import (extract_contents, build_cmds)
+from .exit_code_checker import get_last_exit_code
 
 class IREPLWrapper(replwrap.REPLWrapper):
     """A subclass of REPLWrapper that gives incremental output
@@ -224,7 +225,7 @@ def do_execute(self, code, silent, store_history=True,
             return {'status': 'abort', 'execution_count': self.execution_count}
 
         try:
-            exitcode = int(self.bashwrapper.run_command('{ echo $?; } 2>/dev/null').rstrip().split("\r\n")[0])
+            exitcode =  get_last_exit_code(self.bashwrapper)
         except Exception as exc:
             exitcode = 1
 

tests/test_exit_code_checker.py

@@ -0,0 +1,63 @@
+import os
+import pexpect
+from bash_kernel.kernel import IREPLWrapper
+from bash_kernel.exit_code_checker import get_last_exit_code
+import pytest
+
+
+def test_get_last_exit_code_command_not_found(bashwrapper):
+    bashwrapper.run_command("this-command-does-not-exist")
+    assert get_last_exit_code(bashwrapper) == 127
+
+
+def test_get_last_exit_code_success(bashwrapper):
+    bashwrapper.run_command("echo")
+    assert get_last_exit_code(bashwrapper) == 0
+
+
+def test_get_last_exit_code_command_not_found_conda(mock_conda_bashwrapper):
+    mock_conda_bashwrapper.run_command("this-command-does-not-exist")
+    assert get_last_exit_code(mock_conda_bashwrapper) == 127
+
+
+def test_get_last_exit_code_success_conda(mock_conda_bashwrapper):
+    mock_conda_bashwrapper.run_command("echo")
+    assert get_last_exit_code(mock_conda_bashwrapper) == 0
+
+
+@pytest.fixture(scope="session")
+def mock_conda_bashwrapper(bashwrapper):
+    class FakeCondaWrapper:
+        def __init__(self):
+            self.child = bashwrapper
+
+        def run_command(self, cmd):
+            out = self.child.run_command(cmd)
+            # Simulating the effect of a conda env
+            # on the output of a wrapper
+            return out + "(condaenv)"
+
+    return FakeCondaWrapper()
+
+
+# From BashKernel._start_bash
+@pytest.fixture(scope="session")
+def bashwrapper():
+    unique_prompt = "PROMPT_ASDFASFAS"
+    bashrc = os.path.join(os.path.dirname(pexpect.__file__), "bashrc.sh")
+    child = pexpect.spawn(
+        "bash",
+        ["--rcfile", bashrc],
+        echo=False,
+        encoding="utf-8",
+        codec_errors="replace",
+    )
+
+    ps1 = unique_prompt + "\[\]" + ">"
+    ps2 = unique_prompt + "\[\]" + "+"
+    prompt_change = "PS1='{0}' PS2='{1}' PROMPT_COMMAND=''".format(ps1, ps2)
+    # Using IREPLWrapper to get incremental output
+    bashwrapper = IREPLWrapper(
+        child, "\$", prompt_change, unique_prompt, extra_init_cmd="export PAGER=cat"
+    )
+    return bashwrapper