add test for left_larger_than_right (delta-io#1110)

Signed-off-by: Marijn Valk <marijncv@hotmail.com>

# Description
Adds a test for the `left_larger_than_right` function and rewrites the
function match expression to match on both the `left` and `right`
argument

# Related Issue(s)
<!---
For example:

- closes delta-io#106
--->

# Documentation

<!---
Share links to useful documentation
--->

---------

Signed-off-by: Marijn Valk <marijncv@hotmail.com>

rust/src/delta_datafusion.rs

@@ -686,39 +686,15 @@ fn correct_scalar_value_type(value: ScalarValue, field_dt: &ArrowDataType) -> Op
 }
 
 fn left_larger_than_right(left: ScalarValue, right: ScalarValue) -> Option<bool> {
-    match left {
-        ScalarValue::Float64(Some(v)) => {
-            let f_right = f64::try_from(right).ok()?;
-            Some(v > f_right)
-        }
-        ScalarValue::Float32(Some(v)) => {
-            let f_right = f32::try_from(right).ok()?;
-            Some(v > f_right)
-        }
-        ScalarValue::Int8(Some(v)) => {
-            let i_right = i8::try_from(right).ok()?;
-            Some(v > i_right)
-        }
-        ScalarValue::Int16(Some(v)) => {
-            let i_right = i16::try_from(right).ok()?;
-            Some(v > i_right)
-        }
-        ScalarValue::Int32(Some(v)) => {
-            let i_right = i32::try_from(right).ok()?;
-            Some(v > i_right)
-        }
-        ScalarValue::Int64(Some(v)) => {
-            let i_right = i64::try_from(right).ok()?;
-            Some(v > i_right)
-        }
-        ScalarValue::Boolean(Some(v)) => {
-            let b_right = bool::try_from(right).ok()?;
-            Some(v & !b_right)
-        }
-        ScalarValue::Utf8(Some(v)) => match right {
-            ScalarValue::Utf8(Some(s_right)) => Some(v > s_right),
-            _ => None,
-        },
+    match (&left, &right) {
+        (ScalarValue::Float64(Some(l)), ScalarValue::Float64(Some(r))) => Some(l > r),
+        (ScalarValue::Float32(Some(l)), ScalarValue::Float32(Some(r))) => Some(l > r),
+        (ScalarValue::Int8(Some(l)), ScalarValue::Int8(Some(r))) => Some(l > r),
+        (ScalarValue::Int16(Some(l)), ScalarValue::Int16(Some(r))) => Some(l > r),
+        (ScalarValue::Int32(Some(l)), ScalarValue::Int32(Some(r))) => Some(l > r),
+        (ScalarValue::Int64(Some(l)), ScalarValue::Int64(Some(r))) => Some(l > r),
+        (ScalarValue::Utf8(Some(l)), ScalarValue::Utf8(Some(r))) => Some(l > r),
+        (ScalarValue::Boolean(Some(l)), ScalarValue::Boolean(Some(r))) => Some(l & !r),
         _ => {
             log::error!(
                 "Scalar value comparison unimplemented for {:?} and {:?}",
@@ -1004,6 +980,54 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_left_larger_than_right() {
+        let correct_reference_pairs = vec![
+            (
+                ScalarValue::Float64(Some(1.0)),
+                ScalarValue::Float64(Some(2.0)),
+            ),
+            (
+                ScalarValue::Float32(Some(1.0)),
+                ScalarValue::Float32(Some(2.0)),
+            ),
+            (ScalarValue::Int8(Some(1)), ScalarValue::Int8(Some(2))),
+            (ScalarValue::Int16(Some(1)), ScalarValue::Int16(Some(2))),
+            (ScalarValue::Int32(Some(1)), ScalarValue::Int32(Some(2))),
+            (ScalarValue::Int64(Some(1)), ScalarValue::Int64(Some(2))),
+            (
+                ScalarValue::Boolean(Some(false)),
+                ScalarValue::Boolean(Some(true)),
+            ),
+            (
+                ScalarValue::Utf8(Some(String::from("1"))),
+                ScalarValue::Utf8(Some(String::from("2"))),
+            ),
+        ];
+        for (smaller_val, larger_val) in correct_reference_pairs {
+            assert_eq!(
+                left_larger_than_right(smaller_val.clone(), larger_val.clone()),
+                Some(false)
+            );
+            assert_eq!(left_larger_than_right(larger_val, smaller_val), Some(true));
+        }
+
+        let incorrect_reference_pairs = vec![
+            (
+                ScalarValue::Float64(Some(1.0)),
+                ScalarValue::Float32(Some(2.0)),
+            ),
+            (ScalarValue::Int32(Some(1)), ScalarValue::Float32(Some(2.0))),
+            (
+                ScalarValue::Boolean(Some(true)),
+                ScalarValue::Float32(Some(2.0)),
+            ),
+        ];
+        for (left, right) in incorrect_reference_pairs {
+            assert_eq!(left_larger_than_right(left, right), None);
+        }
+    }
+
     #[test]
     fn test_partitioned_file_from_action() {
         let mut partition_values = std::collections::HashMap::new();