Move Arrow tests to package

Author: Kopilov

dataframe-arrow/src/test/kotlin/ArrowKtTest.kt renamed to dataframe-arrow/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/ArrowKtTest.kt

@@ -1,3 +1,5 @@
+package org.jetbrains.kotlinx.dataframe.io
+
 import io.kotest.assertions.throwables.shouldThrow
 import io.kotest.matchers.collections.shouldContain
 import io.kotest.matchers.shouldBe
@@ -14,12 +16,6 @@ import org.jetbrains.kotlinx.dataframe.api.dataFrameOf
 import org.jetbrains.kotlinx.dataframe.api.map
 import org.jetbrains.kotlinx.dataframe.api.remove
 import org.jetbrains.kotlinx.dataframe.api.toColumn
-import org.jetbrains.kotlinx.dataframe.io.ArrowWriter
-import org.jetbrains.kotlinx.dataframe.io.arrowWriter
-import org.jetbrains.kotlinx.dataframe.io.readArrowFeather
-import org.jetbrains.kotlinx.dataframe.io.readArrowIPC
-import org.jetbrains.kotlinx.dataframe.io.saveArrowIPCToByteArray
-import org.jetbrains.kotlinx.dataframe.io.writeArrowFeather
 import org.junit.Test
 import java.io.File
 import java.net.URL
@@ -135,7 +131,8 @@ internal class ArrowKtTest {
         citiesDeserialized["area"].type() shouldBe typeOf<Float>()
         citiesDeserialized["settled"].type() shouldBe typeOf<LocalDateTime>()
         shouldThrow<IllegalArgumentException> { citiesDeserialized["page_in_wiki"] }
-        citiesDeserialized["film_in_youtube"] shouldBe DataColumn.createValueColumn("film_in_youtube", arrayOfNulls<String>(citiesExampleFrame.rowsCount()).asList())
+        citiesDeserialized["film_in_youtube"] shouldBe DataColumn.createValueColumn("film_in_youtube", arrayOfNulls<String>(
+            citiesExampleFrame.rowsCount()).asList())
     }
 
     @Test

dataframe-arrow/src/test/kotlin/exampleEstimatesAssertions.kt renamed to dataframe-arrow/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/exampleEstimatesAssertions.kt

@@ -1,3 +1,5 @@
+package org.jetbrains.kotlinx.dataframe.io
+
 import io.kotest.matchers.shouldBe
 import org.jetbrains.kotlinx.dataframe.AnyFrame
 import org.jetbrains.kotlinx.dataframe.DataColumn
@@ -14,6 +16,7 @@ import kotlin.reflect.typeOf
 
 /**
  * Assert that we have got the same data that was originally saved on example creation.
+ * Example generation project is currently located at https://github.com/Kopilov/arrow_example
  */
 internal fun assertEstimations(exampleFrame: AnyFrame, expectedNullable: Boolean, hasNulls: Boolean) {
     /**

dataframe-arrow/src/test/kotlin/examplesToWrite.kt renamed to dataframe-arrow/src/test/kotlin/org/jetbrains/kotlinx/dataframe/io/examplesToWrite.kt

@@ -1,3 +1,5 @@
+package org.jetbrains.kotlinx.dataframe.io
+
 import org.jetbrains.kotlinx.dataframe.DataColumn
 import org.jetbrains.kotlinx.dataframe.api.dataFrameOf
 import java.net.URL