Add unit test

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalog.scala

@@ -1209,7 +1209,7 @@ class SessionCatalog(
     databaseExists(db) && externalCatalog.functionExists(db, name.funcName)
   }
 
-  protected def failFunctionLookup(
+  protected[sql] def failFunctionLookup(
       name: FunctionIdentifier, cause: Option[Throwable] = None): Nothing = {
     throw new NoSuchFunctionException(
       db = name.database.getOrElse(getCurrentDatabase), func = name.funcName, cause)

sql/catalyst/src/test/scala/org/apache/spark/sql/catalyst/catalog/SessionCatalogSuite.scala

@@ -1445,4 +1445,12 @@ abstract class SessionCatalogSuite extends AnalysisTest {
       }
     }
   }
+
+  test("SPARK-24544: test print actual failure cause when look up function failed") {
+    withBasicCatalog { catalog =>
+      intercept[NoSuchFunctionException] {
+        catalog.failFunctionLookup(FunctionIdentifier("failureFunc"), Some(new Exception("Test")))
+      }
+    }
+  }
 }