[SPARK-36767][SQL] ArrayMin/ArrayMax/SortArray/ArraySort add comment and Unit test

### What changes were proposed in this pull request?
Add comment about how ArrayMin/ArrayMax/SortArray/ArraySort handle NaN and add Unit test for this

### Why are the changes needed?
Add Unit test

### Does this PR introduce _any_ user-facing change?
No

### How was this patch tested?
Added UT

Closes #34008 from AngersZhuuuu/SPARK-36740.

Authored-by: Angerszhuuuu <angers.zhu@gmail.com>
Signed-off-by: Wenchen Fan <wenchen@databricks.com>
(cherry picked from commit 69e006dd53)
Signed-off-by: Wenchen Fan <wenchen@databricks.com>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/collectionOperations.scala

@@ -914,9 +914,9 @@ object ArraySortLike {
 @ExpressionDescription(
   usage = """
     _FUNC_(array[, ascendingOrder]) - Sorts the input array in ascending or descending order
-      according to the natural ordering of the array elements. Null elements will be placed
+      according to the natural ordering of the array elements. NaN is greater than any non-NaN
-      at the beginning of the returned array in ascending order or at the end of the returned
+      elements for double/float type. Null elements will be placed at the beginning of the returned
-      array in descending order.
+      array in ascending order or at the end of the returned array in descending order.
   """,
   examples = """
     Examples:
@@ -1767,7 +1767,9 @@ case class ArrayJoin(
  * Returns the minimum value in the array.
  */
 @ExpressionDescription(
-  usage = "_FUNC_(array) - Returns the minimum value in the array. NULL elements are skipped.",
+  usage = """
+    _FUNC_(array) - Returns the minimum value in the array. NaN is greater than
+    any non-NaN elements for double/float type. NULL elements are skipped.""",
   examples = """
     Examples:
       > SELECT _FUNC_(array(1, 20, null, 3));
@@ -1838,7 +1840,9 @@ case class ArrayMin(child: Expression)
  * Returns the maximum value in the array.
  */
 @ExpressionDescription(
-  usage = "_FUNC_(array) - Returns the maximum value in the array. NULL elements are skipped.",
+  usage = """
+    _FUNC_(array) - Returns the maximum value in the array. NaN is greater than
+    any non-NaN elements for double/float type. NULL elements are skipped.""",
   examples = """
     Examples:
       > SELECT _FUNC_(array(1, 20, null, 3));

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/expressions/higherOrderFunctions.scala

@@ -351,10 +351,12 @@ case class ArrayTransform(
 // scalastyle:off line.size.limit
 @ExpressionDescription(
   usage = """_FUNC_(expr, func) - Sorts the input array. If func is omitted, sort
-    in ascending order. The elements of the input array must be orderable. Null elements
+    in ascending order. The elements of the input array must be orderable.
-    will be placed at the end of the returned array. Since 3.0.0 this function also sorts
+    NaN is greater than any non-NaN elements for double/float type.
-    and returns the array based on the given comparator function. The comparator will
+    Null elements will be placed at the end of the returned array.
-    take two arguments representing two elements of the array.
+    Since 3.0.0 this function also sorts and returns the array based on the
+    given comparator function. The comparator will take two arguments representing
+    two elements of the array.
     It returns -1, 0, or 1 as the first element is less than, equal to, or greater
     than the second element. If the comparator function returns other
     values (including null), the function will fail and raise an error.

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/CollectionExpressionsSuite.scala

@@ -2331,4 +2331,21 @@ class CollectionExpressionsSuite extends SparkFunSuite with ExpressionEvalHelper
       Literal.create(Seq(Float.NaN, null), ArrayType(FloatType)),
       Literal.create(Seq(Float.NaN, null, 1f), ArrayType(FloatType))), true)
   }
+
+  test("SPARK-36740: ArrayMin/ArrayMax/SortArray should handle NaN greater then non-NaN value") {
+    // ArrayMin
+    checkEvaluation(ArrayMin(
+      Literal.create(Seq(Double.NaN, 1d, 2d), ArrayType(DoubleType))), 1d)
+    checkEvaluation(ArrayMin(
+      Literal.create(Seq(Double.NaN, 1d, 2d, null), ArrayType(DoubleType))), 1d)
+    // ArrayMax
+    checkEvaluation(ArrayMax(
+      Literal.create(Seq(Double.NaN, 1d, 2d), ArrayType(DoubleType))), Double.NaN)
+    checkEvaluation(ArrayMax(
+      Literal.create(Seq(Double.NaN, 1d, 2d, null), ArrayType(DoubleType))), Double.NaN)
+    // SortArray
+    checkEvaluation(new SortArray(
+      Literal.create(Seq(Double.NaN, 1d, 2d, null), ArrayType(DoubleType))),
+      Seq(null, 1d, 2d, Double.NaN))
+  }
 }

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/expressions/HigherOrderFunctionsSuite.scala

@@ -832,4 +832,10 @@ class HigherOrderFunctionsSuite extends SparkFunSuite with ExpressionEvalHelper
     assert(mapFilter2_1.semanticEquals(mapFilter2_2))
     assert(!mapFilter2_1.semanticEquals(mapFilter2_3))
   }
+
+  test("SPARK-36740: ArraySort should handle NaN greater then non-NaN value") {
+    checkEvaluation(arraySort(
+      Literal.create(Seq(Double.NaN, 1d, 2d, null), ArrayType(DoubleType))),
+      Seq(1d, 2d, Double.NaN, null))
+  }
 }

sql/core/src/main/scala/org/apache/spark/sql/functions.scala

@@ -3815,6 +3815,7 @@ object functions {
 
   /**
    * Sorts the input array in ascending order. The elements of the input array must be orderable.
+   * NaN is greater than any non-NaN elements for double/float type.
    * Null elements will be placed at the end of the returned array.
    *
    * @group collection_funcs
@@ -4524,8 +4525,9 @@ object functions {
 
   /**
    * Sorts the input array for the given column in ascending or descending order,
-   * according to the natural ordering of the array elements.
+   * according to the natural ordering of the array elements. NaN is greater than any non-NaN
-   * Null elements will be placed at the beginning of the returned array in ascending order or
+   * elements for double/float type. Null elements will be placed at the beginning of the returned
+   * array in ascending order or
    * at the end of the returned array in descending order.
    *
    * @group collection_funcs
@@ -4534,7 +4536,8 @@ object functions {
   def sort_array(e: Column, asc: Boolean): Column = withExpr { SortArray(e.expr, lit(asc).expr) }
 
   /**
-   * Returns the minimum value in the array.
+   * Returns the minimum value in the array. NaN is greater than any non-NaN elements for
+   * double/float type. NULL elements are skipped.
    *
    * @group collection_funcs
    * @since 2.4.0
@@ -4542,7 +4545,8 @@ object functions {
   def array_min(e: Column): Column = withExpr { ArrayMin(e.expr) }
 
   /**
-   * Returns the maximum value in the array.
+   * Returns the maximum value in the array. NaN is greater than any non-NaN elements for
+   * double/float type. NULL elements are skipped.
    *
    * @group collection_funcs
    * @since 2.4.0