message: Add reduce window tests for the cases when the input shape has 1 element.
diff: @@ -1351,5 +1351,41 @@ ENTRY R2Window {
  EXPECT_TRUE(RunAndCompare(hlo_string, ErrorSpec{0.001}));
  }
  +TEST_F(ReduceWindowTextTest, R2EffectiveScalar) {
  + const string& hlo_string = R"(
  +HloModule R2Window
  +mul {
  + lhs = f32[] parameter(0)
  + rhs = f32[] parameter(1)
  + ROOT mul = f32[] multiply(lhs, rhs)
  +}
  +ENTRY R2Window {
  + operand = f32[1,1]{1,0} parameter(0)
  + negate = f32[1,1]{1,0} negate(operand)
  + constant = f32[] constant(1)
  + ROOT reduce-window = f32[1,1]{1,0} reduce-window(negate, constant), window={size=1x1 pad=0_0x0_0}, to_apply=mul
  +}
  +)";
  + EXPECT_TRUE(RunAndCompare(hlo_string, ErrorSpec{0.001}));
  +}
  +
  +TEST_F(ReduceWindowTextTest, R3EffectiveScalar) {
  + const string& hlo_string = R"(
  +HloModule R3Window
  +mul {
  + lhs = f32[] parameter(0)
  + rhs = f32[] parameter(1)
  + ROOT mul = f32[] multiply(lhs, rhs)
  +}
  +ENTRY R3Window {
  + operand = f32[1,1,1]{2,1,0} parameter(0)
  + negate = f32[1,1,1]{2,1,0} negate(operand)
  + constant = f32[] constant(1)
  + ROOT reduce-window = f32[1,1,1]{2,1,0} reduce-window(negate, constant), window={size=1x1x1 pad=0_0x0_0x0_0}, to_apply=mul
  +}
  +)";
  + EXPECT_TRUE(RunAndCompare(hlo_string, ErrorSpec{0.001}));
  +}
  +
  } // namespace
  } // namespace xla
  