Add tests for MathicsSession objects. Fix MathicsSession.format (#1549)

This PR adds a Pytest module for checking the basic behaviour of the
MathicsSession object.

Author: mmatera

mathics/core/systemsymbols.py

@@ -93,6 +93,7 @@
 SymbolDigitCharacter = Symbol("System`DigitCharacter")
 SymbolDirectedInfinity = Symbol("System`DirectedInfinity")
 SymbolDispatch = Symbol("System`Dispatch")
+SymbolDivide = Symbol("System`Divide")
 SymbolDot = Symbol("System`Dot")
 SymbolDownValues = Symbol("System`DownValues")
 SymbolDrop = Symbol("System`Drop")

mathics/session.py

@@ -174,13 +174,14 @@ def evaluate_as_in_cli(self, str_expression, timeout=None, form=None, src_name="
         return res
 
     def format_result(self, str_expression=None, timeout=None, form=None):
+        if form is None:
+            form = self.form
+
         if str_expression:
-            self.evaluate(str_expression, timeout=None, form=None)
+            return self.evaluate(str_expression, timeout=timeout, form=form)
 
         res = self.last_result
-        if form is None:
-            form = self.form
-        return res.do_format(self.evaluation, form)
+        return self.evaluation.format_output(res, form)
 
     def parse(self, str_expression, src_name=""):
         """

test/builtin/box/test_custom_boxexpression.py

@@ -98,8 +98,7 @@ def test_custom_boxconstruct():
     defs = session.evaluation.definitions
     instance_custom_atom = CustomAtom(expression=False)
     instance_custom_atom.contribute(defs, is_pymodule=True)
-    evaluate("MakeBoxes[CustomAtom, InputForm]")
-    formatted = session.format_result().boxes_to_mathml()
+    formatted = session.evaluate("MakeBoxes[InputForm[CustomAtom]]").boxes_to_mathml()
     assert formatted == "CustomBoxExpression<<[1, 2, 3]>>"
 
 
@@ -109,8 +108,8 @@ def test_custom_graphicsbox_constructor():
         expression=False, evaluation=session.evaluation
     )
     instance_customgb_atom.contribute(defs, is_pymodule=True)
-    evaluate("MakeBoxes[Graphics[{Circle[{0,0},1]}], OutputForm]")
-    formatted = session.format_result().boxes_to_mathml()
+    result = session.evaluate("MakeBoxes[OutputForm[Graphics[{Circle[{0,0},1]}]]]")
+    formatted = result.boxes_to_mathml()
     assert (
         formatted
         == "--custom graphics--: I should plot (<Expression: <Symbol: System`Circle>[<ListExpression: (<Integer: 0>, <Integer: 0>)>, <Integer: 1>]>,) items"

test/test_session.py

@@ -0,0 +1,78 @@
+# -*- coding: utf-8 -*-
+"""
+Basic tests for the MathicsSession class.
+
+"""
+
+
+from mathics.core.atoms import Integer1, Integer2, IntegerM1
+from mathics.core.evaluation import Result
+from mathics.core.expression import Expression
+from mathics.core.symbols import Symbol, SymbolNull
+from mathics.core.systemsymbols import SymbolDirectedInfinity, SymbolPower, SymbolTimes
+from mathics.session import MathicsSession
+
+session = MathicsSession()
+
+
+def test_session_evaluation():
+    """Some basic tests"""
+    session.reset()
+    assert session.evaluate("(**)") is SymbolNull
+    assert session.evaluate("1/0").sameQ(Expression(SymbolDirectedInfinity))
+    out = session.evaluation.out
+    assert (
+        len(session.evaluation.out) == 1
+        and out[0].text == "Infinite expression 1 / 0 encountered."
+    )
+    assert session.evaluate("F[x]").sameQ(
+        Expression(Symbol("Global`F"), Symbol("Global`x"))
+    )
+    assert len(session.evaluation.out) == 0
+    assert session.evaluate("$Line") is Symbol("$Line")
+
+
+def test_session_evaluation_as_in_cli():
+    # `evaluation_as_in_cli` returns a `Result` object
+    session.reset()
+    assert session.evaluate("$Line") is Symbol("$Line")
+    result = session.evaluate_as_in_cli('Print["Hola"]')
+    assert isinstance(result, Result)
+    assert len(result.out) == 1 and result.out[0].text == "Hola"
+    # Use session.evaluate(...) does not modify the `$Line` or
+    # `Out` definitions, while `evaluate_as_in_cli` does:
+    assert session.evaluate("$Line") is Integer1
+    assert session.evaluate_as_in_cli("$Line", form="unformatted").result == Integer2
+    assert session.evaluate("Out[1]") is SymbolNull
+    assert session.evaluate_as_in_cli("Out[1]").result is None
+    session.reset()
+    assert session.evaluate("$Line") is Symbol("$Line")
+
+
+def test_session_format_evaluation():
+    result = session.evaluate("a/b")
+    assert session.format_result(form="unformatted").sameQ(result)
+    assert session.format_result(form="text") == "a / b"
+    assert session.format_result(form="latex") == "\\frac{a}{b}"
+    assert session.format_result(form="xml") == (
+        '<math display="block"><mfrac>' "<mi>a</mi> <mi>b</mi>" "</mfrac></math>"
+    )
+
+
+def test_session_parse():
+    parsed = session.parse("a/b")
+    expected = Expression(
+        SymbolTimes,
+        Symbol("Global`a"),
+        Expression(SymbolPower, Symbol("Global`b"), IntegerM1),
+    )
+    print("parsed:", parsed)
+    print("expected:", expected)
+    assert parsed.sameQ(expected)
+
+
+if __name__ == "__main__":
+    test_session_evaluation()
+    test_session_evaluation_as_in_cli()
+    test_session_format_evaluation()
+    test_session_parse()