Fix: correct ATAN(x, y) and CONV(x, a, b) functions bug (opensearch-project#3748)

* Fix: correct ATAN(x, y) and CONV(x, a, b) functions bug

Signed-off-by: Hao <haoxinyu@842f57420e85.ant.amazon.com>
Signed-off-by: Xinyu Hao <haoxinyu@amazon.com>

* Fix: correct ATAN(x, y) and CONV(x, a, b) functions bug

Signed-off-by: Xinyu Hao <haoxinyu@amazon.com>

* Fix: correct atan convolution bug and enable tests

Signed-off-by: Xinyu Hao <haoxinyu@amazon.com>

* Fix: correct ATAN(x, y) and CONV(x, a, b) functions bug and enable tests

Signed-off-by: Xinyu Hao <haoxinyu@amazon.com>

---------

Signed-off-by: Hao <haoxinyu@842f57420e85.ant.amazon.com>
Signed-off-by: Xinyu Hao <haoxinyu@amazon.com>

Author: ishaoxy

core/src/main/java/org/opensearch/sql/expression/function/PPLFuncImpTable.java

@@ -832,6 +832,11 @@ void populate() {
                       builder.makeLiteral(" "),
                       arg),
               PPLTypeChecker.family(SqlTypeFamily.STRING)));
+      register(
+          ATAN,
+          createFunctionImpWithTypeChecker(
+              (builder, arg1, arg2) -> builder.makeCall(SqlStdOperatorTable.ATAN2, arg1, arg2),
+              PPLTypeChecker.family(SqlTypeFamily.NUMERIC, SqlTypeFamily.NUMERIC)));
       register(
           STRCMP,
           createFunctionImpWithTypeChecker(

core/src/main/java/org/opensearch/sql/expression/function/udf/math/ConvFunction.java

@@ -57,7 +57,7 @@ public Expression implement(
       Expression toBase = translatedOperands.get(2);
       if (numberType.getFamily() == SqlTypeFamily.NUMERIC) {
         // Convert the first operand to String
-        number = Expressions.call(Object.class, "toString", number);
+        number = Expressions.call(Expressions.box(number), "toString");
       }
       return Expressions.call(ConvImplementor.class, "conv", number, fromBase, toBase);
     }

integ-test/src/test/java/org/opensearch/sql/calcite/remote/CalciteMathematicalFunctionIT.java

@@ -5,8 +5,6 @@
 
 package org.opensearch.sql.calcite.remote;
 
-import java.io.IOException;
-import org.junit.Ignore;
 import org.opensearch.sql.ppl.MathematicalFunctionIT;
 
 public class CalciteMathematicalFunctionIT extends MathematicalFunctionIT {
@@ -16,16 +14,4 @@ public void init() throws Exception {
     enableCalcite();
     disallowCalciteFallback();
   }
-
-  @Override
-  @Ignore("https://github.com/opensearch-project/sql/issues/3672")
-  public void testAtan() throws IOException {
-    super.testAtan();
-  }
-
-  @Override
-  @Ignore("https://github.com/opensearch-project/sql/issues/3672")
-  public void testConv() throws IOException {
-    super.testConv();
-  }
 }