implement sage's feature for FriCAS

This is taken from #33575

Author: Matthias Koeppe

src/sage/features/interfaces.py

@@ -14,7 +14,7 @@
 
 import importlib
 
-from . import Feature, FeatureTestResult, PythonModule
+from . import Executable, Feature, FeatureTestResult, PythonModule
 
 
 class InterfaceFeature(Feature):
@@ -37,7 +37,7 @@ class InterfaceFeature(Feature):
         "Interface also_broken_interface cannot be imported: module 'sage.interfaces.interface' has no attribute 'also_broken_interface'"
     """
     @staticmethod
-    def __classcall__(cls, name, module, description=None):
+    def __classcall__(cls, name, module, description=None, **kwds):
         """
         TESTS::
 
@@ -49,9 +49,9 @@ def __classcall__(cls, name, module, description=None):
         """
         if isinstance(module, str):
             module = PythonModule(module)
-        return Feature.__classcall__(cls, name, module, description)
+        return Feature.__classcall__(cls, name, module, description, **kwds)
 
-    def __init__(self, name, module, description):
+    def __init__(self, name, module, description, **kwds):
         """
         TESTS::
 
@@ -60,7 +60,7 @@ def __init__(self, name, module, description):
             sage: isinstance(f, InterfaceFeature)
             True
         """
-        super().__init__(name, description=description)
+        super().__init__(name, description=description, **kwds)
         self.module = module
 
     def _is_present(self):
@@ -90,6 +90,38 @@ def _is_present(self):
                                      reason=f"Interface {interface} is not functional: {exception}")
 
 
+class FriCASExecutable(Executable):
+    r"""
+    A :class:`~sage.features.Feature` describing whether :class:`sage.interfaces.fricas.FriCAS`
+    is present and functional.
+
+    EXAMPLES::
+
+        sage: from sage.features.interfaces import FriCASExecutable
+        sage: FriCASExecutable().is_present()  # random
+        FeatureTestResult('fricas_exe', False)
+    """
+    @staticmethod
+    def __classcall__(cls):
+        return Executable.__classcall__(cls, 'fricas_exe', 'fricas', spkg='fricas')
+
+
+class FriCAS(InterfaceFeature):
+    r"""
+    A :class:`~sage.features.Feature` describing whether :class:`sage.interfaces.fricas.FriCAS`
+    is present and functional.
+
+    EXAMPLES::
+
+        sage: from sage.features.interfaces import FriCAS
+        sage: FriCAS().is_present()  # random
+        FeatureTestResult('fricas', False)
+    """
+    @staticmethod
+    def __classcall__(cls):
+        return InterfaceFeature.__classcall__(cls, 'fricas', 'sage.interfaces.fricas', spkg='fricas')
+
+
 # The following are provided by external software only (no SPKG)
 
 class Magma(InterfaceFeature):
@@ -219,15 +251,17 @@ def all_features():
 
         sage: from sage.features.interfaces import all_features
         sage: list(all_features())
-        [Feature('magma'),
+        [Feature('fricas'),
+         Feature('magma'),
          Feature('matlab'),
          Feature('mathematica'),
          Feature('maple'),
          Feature('macaulay2'),
          Feature('octave'),
          Feature('scilab')]
     """
-    return [Magma(),
+    return [FriCAS(),
+            Magma(),
             Matlab(),
             Mathematica(),
             Maple(),

src/sage/interfaces/fricas.py

@@ -264,7 +264,7 @@ 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):
         """
@@ -289,6 +289,10 @@ def __init__(self, name='fricas', command='fricas -nosman',
             sage: fricas(I*x).sage()                                            # optional - fricas
             I*x
         """
+        if command is None:
+            from sage.features.interfaces import FriCASExecutable
+            fricas_exe = FriCASExecutable().absolute_filename()
+            command = f'{fricas_exe} -nosman'
         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