add test / fix for lpdot

pulp/pulp.py

@@ -2234,12 +2234,15 @@ def lpSum(vector):
 
 
 def lpDot(v1, v2):
+    v1_iterable = const.isiterable(v1) and not isinstance(v1, LpAffineExpression)
+    v2_iterable = const.isiterable(v2) and not isinstance(v2, LpAffineExpression)
+
     """Calculate the dot product of two lists of linear expressions"""
-    if not const.isiterable(v1) and not const.isiterable(v2):
+    if not v1_iterable and not v2_iterable:
         return v1 * v2
-    elif not const.isiterable(v1):
+    elif not v1_iterable:
         return lpDot([v1] * len(v2), v2)
-    elif not const.isiterable(v2):
+    elif not v2_iterable:
         return lpDot(v1, [v2] * len(v1))
     else:
         return lpSum([lpDot(e1, e2) for e1, e2 in zip(v1, v2)])

pulp/tests/test_lpdot.py

@@ -0,0 +1,8 @@
+from pulp import lpDot, LpVariable
+
+
+def test_lpdot():
+    x = LpVariable(name="x")
+
+    product = lpDot([1], [2 * x])
+    assert product.toDict() == [{"name": "x", "value": 2}]