fix: Prevent invalid syntax for no-op .replace ops (#2112)

TrevorBergeron · web-flow · commit c311876b2adb · 2025-09-29T14:27:42.000-07:00
diff --git a/bigframes/core/compile/ibis_compiler/scalar_op_registry.py b/bigframes/core/compile/ibis_compiler/scalar_op_registry.py
@@ -1173,6 +1173,10 @@ def udf(*inputs):
 
 @scalar_op_compiler.register_unary_op(ops.MapOp, pass_op=True)
 def map_op_impl(x: ibis_types.Value, op: ops.MapOp):
+    # this should probably be handled by a rewriter
+    if len(op.mappings) == 0:
+        return x
+
     case = ibis_api.case()
     for mapping in op.mappings:
         case = case.when(x == mapping[0], mapping[1])
diff --git a/bigframes/core/compile/sqlglot/expressions/generic_ops.py b/bigframes/core/compile/sqlglot/expressions/generic_ops.py
@@ -78,6 +78,8 @@ def _(expr: TypedExpr) -> sge.Expression:
 
 @register_unary_op(ops.MapOp, pass_op=True)
 def _(expr: TypedExpr, op: ops.MapOp) -> sge.Expression:
+    if len(op.mappings) == 0:
+        return expr.expr
     return sge.Case(
         this=expr.expr,
         ifs=[
diff --git a/tests/system/small/test_series.py b/tests/system/small/test_series.py
@@ -733,10 +733,12 @@ def test_series_replace_nans_with_pd_na(scalars_dfs):
     (
         ({"Hello, World!": "Howdy, Planet!", "T": "R"},),
         ({},),
+        ({0: "Hello, World!"},),
     ),
     ids=[
         "non-empty",
         "empty",
+        "off-type",
     ],
 )
 def test_series_replace_dict(scalars_dfs, replacement_dict):

Original file line number	Diff line number	Diff line change
`@@ -733,10 +733,12 @@ def test_series_replace_nans_with_pd_na(scalars_dfs):`
`733`	`733`	`(`
`734`	`734`	`({"Hello, World!": "Howdy, Planet!", "T": "R"},),`
`735`	`735`	`({},),`
	`736`	`+ ({0: "Hello, World!"},),`
`736`	`737`	`),`
`737`	`738`	`ids=[`
`738`	`739`	`"non-empty",`
`739`	`740`	`"empty",`
	`741`	`+ "off-type",`
`740`	`742`	`],`
`741`	`743`	`)`
`742`	`744`	`def test_series_replace_dict(scalars_dfs, replacement_dict):`