Correct math.inf. Add test

Author: rocky

mathics/builtin/arithmetic.py

@@ -1340,6 +1340,8 @@ class I(Predefined):
      = 10
     """
 
+    python_equivalent = 1j
+
     def evaluate(self, evaluation):
         return Complex(Integer(0), Integer(1))
 

mathics/builtin/inout.py

@@ -1947,7 +1947,7 @@ class PythonForm(Builtin):
     </dl>
 
     >> PythonForm[Infinity]
-    = inf
+    = math.inf
     >> PythonForm[Pi]
     = sympy.pi
     >> E // PythonForm

mathics/core/expression.py

@@ -2635,6 +2635,8 @@ def __new__(cls, value):
         self = super(StringFromPython, cls).__new__(cls, value)
         if isinstance(value, sympy.NumberSymbol):
             self.value = "sympy." + str(value)
+        elif value == math.inf:
+            self.value = "math.inf"
         return self
 
 

test/test_to_python.py

@@ -0,0 +1,32 @@
+# -*- coding: utf-8 -*-
+from .helper import session, check_evaluation
+
+import math
+import sympy
+import sys
+from mathics.core.parser import parse, SingleLineFeeder
+from mathics.core.definitions import Definitions
+from mathics.core.evaluation import Evaluation
+import pytest
+
+
+def test_to_infinity():
+    for str_expr, str_expected, message in (
+        (
+            "PythonForm[Infinity]",
+            '"math.inf"',
+            "Infinity",
+        ),
+        (
+            "PythonForm[{1, 2, 3, 4}]",
+            '"[1, 2, 3, 4]"',
+            "Simple List of integers",
+        ),
+        (
+            "Pi // PythonForm",
+            '"sympy.pi"',
+            "Pi",
+        ),
+
+    ):
+        check_evaluation(str_expr, str_expected, message)