Lint found in ListPlot-point checking branch (#1246)

The good stuff from #1245, but alas the thing we were trying to do there can cause an infinite loop in the eval_ListPlot routine. So let's do this part and narrow that PR.

.github/workflows/packages.yml

@@ -38,6 +38,6 @@ jobs:
         cd mathics/packages/Combinatorica-repo
         # If Combinatorica repo changes, we may need the below altered
         # with a branch name, (not HEAD) for testing.
-        # git pull origin HEAD
+        git pull origin HEAD
         pip install -e .[dev]
         remake -x check

mathics/core/expression.py

@@ -1417,8 +1417,13 @@ def rules():
                 if not isinstance(result, EvalMixin):
                     return result, False
                 if result.sameQ(new):
-                    new._timestamp_cache(evaluation)
-                    return new, False
+                    # Even though result and new may be the same,
+                    # new can be a Expression[SymbolConstant: System`List...]
+                    # while "result' might be ListExpression!?
+                    # So make sure to use "result", not "new".
+                    if isinstance(result, Expression):
+                        result._timestamp_cache(evaluation)
+                    return result, False
                 else:
                     return result, True
 

mathics/eval/drawing/plot.py

@@ -201,19 +201,20 @@ def eval_ListPlot(
             [xx for xx, yy in plot_groups], [xx for xx, yy in plot_groups], x_range
         )
         plot_groups = [plot_groups]
-    elif all(isinstance(line, list) for line in plot_groups):
-        if not all(isinstance(line, list) for line in plot_groups):
+    elif all(isinstance(line, (list, tuple)) for line in plot_groups):
+        if not all(isinstance(line, (list, tuple)) for line in plot_groups):
             return
 
         # He have a list of plot groups
         if all(
-            isinstance(point, list) and len(point) == 2
-            for plot_group in plot_groups
+            isinstance(point, (list, tuple)) and len(point) == 2
             for point in plot_groups
         ):
             pass
         elif not is_discrete_plot and all(
-            not isinstance(point, list) for line in plot_groups for point in line
+            not isinstance(point, (list, tuple))
+            for line in plot_groups
+            for point in line
         ):
             # FIXME: is this right?
             y_min = min(plot_groups)[0]
@@ -229,7 +230,7 @@ def eval_ListPlot(
     # Split into plot segments
     plot_groups = [[plot_group] for plot_group in plot_groups]
     if isinstance(x_range, (list, tuple)):
-        x_min, m_max = x_range
+        x_min, x_max = x_range
         y_min, y_max = y_range
 
     for lidx, plot_group in enumerate(plot_groups):

test/helper.py

@@ -38,7 +38,7 @@ def evaluate(str_expr: str):
 def check_evaluation(
     str_expr: Optional[str],
     str_expected: Optional[str] = None,
-    failure_message: str = "",
+    failure_message: Optional[str] = "",
     hold_expected: bool = False,
     to_string_expr: Optional[bool] = True,
     to_string_expected: bool = True,