fix(sql): case_when now passes pandas tests

siuba/sql/verbs/conditional.py

@@ -5,6 +5,9 @@
 from siuba.dply.verbs import case_when, if_else
 from siuba.siu import Call
 
+from ..backend import LazyTbl
+
+
 @case_when.register(sql.base.ImmutableColumnCollection)
 def _case_when(__data, cases):
     # TODO: will need listener to enter case statements, to handle when they use windows
@@ -22,14 +25,22 @@ def _case_when(__data, cases):
             val = val(__data)
 
         # handle when expressions
-        if ii+1 == n_items and expr is True:
-            else_val = val
-        elif callable(expr):
+        #if ii+1 == n_items and expr is True:
+        #    else_val = val
+        if callable(expr):
             whens.append((expr(__data), val))
         else:
             whens.append((expr, val))
 
     return sql.case(whens, else_ = else_val)
+
+
+@case_when.register(LazyTbl)
+def _case_when(__data, cases):
+    raise NotImplementedError(
+        "`case_when()` must be used inside a verb like `mutate()`, when using a "
+        "SQL backend."
+    )
 
 
 # if_else ---------------------------------------------------------------------

siuba/tests/test_verb_case_when.py

@@ -2,10 +2,13 @@
 import numpy as np
 import pytest
 
-from siuba.dply.verbs import case_when
 from pandas.testing import assert_series_equal
 from numpy.testing import assert_equal
+from siuba.tests.helpers import assert_equal_query
+
 from siuba.siu import _
+from siuba.dply.verbs import case_when, mutate
+
 
 DATA = pd.DataFrame({
     'x': [0,1,2],
@@ -18,7 +21,7 @@ def data():
     return DATA.copy()
 
 
-@pytest.mark.parametrize("k,v, res", [
+@pytest.mark.parametrize("k,v, dst", [
     (True, 1,     [1]*3),
     (True, False, [False]*3),
     (True, _.y,   [10, 11, 12]),
@@ -29,10 +32,18 @@ def data():
     (lambda _: _.x < 2, 0,  [0, 0, None]),
     #(np.array([True, True, False]), 0, [0, 0, None])
     ])
-def test_case_when_single_cond(k, v, res, data):
-    out = case_when(data, {k: v})
+def test_case_when_single_cond(backend, data, k, v, dst):
+    src = backend.load_df(data)
+    query = mutate(_, res = case_when(_, {k: v}))
+
+    assert_equal_query(src, query, data.assign(res = dst))
+
+
+def test_case_when_multiple_clauses(backend, data):
+    src = backend.load_df(data)
+    query = mutate(_, res = case_when({_.x == 0: "zero", _.x > 1: "big", True: "small"}))
 
-    assert_series_equal(out, pd.Series(res))
+    assert_equal_query(src, query, data.assign(res = ["zero", "small", "big"]))
 
 
 def test_case_when_cond_order(data):