updated design of feature

src/sage/features/fricas.py

@@ -0,0 +1,65 @@
+r"""
+Features for testing the presence of ``fricas``
+"""
+
+# *****************************************************************************
+#       Copyright (C) 2023 Dima Pasechnik
+#
+#  Distributed under the terms of the GNU General Public License (GPL)
+#  as published by the Free Software Foundation; either version 2 of
+#  the License, or (at your option) any later version.
+#                  https://www.gnu.org/licenses/
+# *****************************************************************************
+
+import os
+import subprocess
+from . import Executable, FeatureTestResult
+
+class FriCAS(Executable):
+    r"""
+    A :class:`~sage.features.Feature` which checks for the :ref:`fricas <fricas>` binary.
+
+    EXAMPLES::
+
+        sage: from sage.features.fricas import FriCAS
+        sage: FriCAS().is_present()  # optional - fricas
+        FeatureTestResult('fricas', True)
+    """
+    def __init__(self):
+        r"""
+        TESTS::
+
+            sage: from sage.features.fricas import FriCAS
+            sage: isinstance(FriCAS(), FriCAS)
+            True
+        """
+        Executable.__init__(self, name="fricas", spkg="fricas",
+                            executable="fricas",
+                            url="https://fricas.github.io")
+
+    def is_functional(self):
+        r"""
+        Check whether ``fricas`` works on trivial input.
+
+        EXAMPLES::
+
+            sage: from sage.features.fricas import FriCAS
+            sage: FriCAS().is_functional()  # optional - fricas
+            FeatureTestResult('fricas', True)
+        """
+        command = ["fricas -nosman", "2+2"]
+        try:
+            lines = subprocess.check_output(command, stderr=subprocess.STDOUT)
+        except subprocess.CalledProcessError as e:
+            return FeatureTestResult(self, False,
+                    reason="Call `{command}` failed with exit code {e.returncode}".format(command=" ".join(command), e=e))
+
+        expected = b"4"
+        if lines.find(expected) == -1:
+            return FeatureTestResult(self, False,
+                    reason="Call `{command}` did not produce output which contains `{expected}`".format(command=" ".join(command), expected=expected))
+
+        return FeatureTestResult(self, True)
+
+def all_features():
+    return [FriCAS()]

src/sage/interfaces/fricas.py

@@ -264,9 +264,9 @@ class FriCAS(ExtraTabCompletion, Expect):
     """
     Interface to a FriCAS interpreter.
     """
-    def __init__(self, name='fricas', command='fricas -nosman',
+    def __init__(self, name='fricas', command=None,
                  script_subdirectory=None, logfile=None,
-                 server=None, server_tmpdir=None):
+                 server=None, server_tmpdir=None, options="-nosman"):
         """
         Create an instance of the FriCAS interpreter.
 
@@ -289,6 +289,13 @@ def __init__(self, name='fricas', command='fricas -nosman',
             sage: fricas(I*x).sage()                                            # optional - fricas
             I*x
         """
+        from sage.features.fricas import FriCAS
+        FriCAS().require()
+
+        import shlex
+        command = '{} {}'.format(shlex.quote(FriCAS().absolute_filename()),
+                                 options)
+
         eval_using_file_cutoff = 4096 - 5  # magic number from Expect._eval_line (there might be a bug)
         assert max(len(c) for c in FRICAS_INIT_CODE) < eval_using_file_cutoff
         self.__eval_using_file_cutoff = eval_using_file_cutoff