Fix reading null booleans from CSV

arrow-csv/src/reader/mod.rs

@@ -866,6 +866,9 @@ fn build_boolean_array(
         .enumerate()
         .map(|(row_index, row)| {
             let s = row.get(col_idx);
+            if s.is_empty() {
+                return Ok(None);
+            }
             let parsed = parse_bool(s);
             match parsed {
                 Some(e) => Ok(Some(e)),
@@ -1122,6 +1125,7 @@ mod tests {
     use std::io::{Cursor, Write};
     use tempfile::NamedTempFile;
 
+    use arrow_array::cast::as_boolean_array;
     use chrono::prelude::*;
 
     #[test]
@@ -2067,4 +2071,30 @@ mod tests {
             assert_eq!(b.num_rows(), expected, "{}", idx);
         }
     }
+
+    #[test]
+    fn test_null_boolean() {
+        let csv = "true,false\nFalse,True\n,True\n";
+        let b = ReaderBuilder::new()
+            .build_buffered(Cursor::new(csv.as_bytes()))
+            .unwrap()
+            .next()
+            .unwrap()
+            .unwrap();
+
+        assert_eq!(b.num_rows(), 3);
+        assert_eq!(b.num_columns(), 2);
+
+        let c = as_boolean_array(b.column(0));
+        assert_eq!(c.null_count(), 1);
+        assert!(c.value(0));
+        assert!(!c.value(1));
+        assert!(c.is_null(2));
+
+        let c = as_boolean_array(b.column(1));
+        assert_eq!(c.null_count(), 0);
+        assert!(!c.value(0));
+        assert!(c.value(1));
+        assert!(c.value(2));
+    }
 }