diff --git a/.idea/codeStyles/Project.xml b/.idea/codeStyles/Project.xml
index 1bec35e..c5dd6f7 100644
--- a/.idea/codeStyles/Project.xml
+++ b/.idea/codeStyles/Project.xml
@@ -1,10 +1,14 @@
 <component name="ProjectCodeStyleConfiguration">
   <code_scheme name="Project" version="173">
     <JetCodeStyleSettings>
+      <option name="SPACE_BEFORE_EXTEND_COLON" value="false" />
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
     </JetCodeStyleSettings>
     <codeStyleSettings language="kotlin">
       <option name="CODE_STYLE_DEFAULTS" value="KOTLIN_OFFICIAL" />
+      <indentOptions>
+        <option name="CONTINUATION_INDENT_SIZE" value="4" />
+      </indentOptions>
     </codeStyleSettings>
   </code_scheme>
 </component>
\ No newline at end of file
diff --git a/src/main/kotlin/fr/postgresjson/migration/Function.kt b/src/main/kotlin/fr/postgresjson/migration/Function.kt
index fe09d26..3f35da3 100644
--- a/src/main/kotlin/fr/postgresjson/migration/Function.kt
+++ b/src/main/kotlin/fr/postgresjson/migration/Function.kt
@@ -7,7 +7,7 @@ import java.io.File
 import java.util.*
 import fr.postgresjson.definition.Function as DefinitionFunction
 
-class Function(
+data class Function(
     val up: DefinitionFunction,
     val down: DefinitionFunction,
     private val connection: Connection,
@@ -26,8 +26,8 @@ class Function(
         up: String,
         down: String,
         connection: Connection,
-        executedAt: Date? = null):
-    this(
+        executedAt: Date? = null
+    ): this(
         DefinitionFunction(up),
         DefinitionFunction(down),
         connection,
@@ -74,4 +74,10 @@ class Function(
 
         return Status.OK // TODO
     }
+
+    fun copy(): Function {
+        return this.copy(up = up, down = down, connection = connection, executedAt = executedAt).also {
+            it.doExecute = this.doExecute
+        }
+    }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/fr/postgresjson/migration/Migrations.kt b/src/main/kotlin/fr/postgresjson/migration/Migrations.kt
index 962340f..a10efef 100644
--- a/src/main/kotlin/fr/postgresjson/migration/Migrations.kt
+++ b/src/main/kotlin/fr/postgresjson/migration/Migrations.kt
@@ -27,15 +27,15 @@ interface Migration {
     fun status(): Status
 
     enum class Status(i: Int) { OK(2), UP_FAIL(0), DOWN_FAIL(1) }
-    enum class Action { OK, UP, DOWN}
+    enum class Action { OK, UP, DOWN }
 }
 
-class Migrations(directory: File, private val connection: Connection) {
-    private val queries: MutableMap<String, Query> = mutableMapOf()
+data class Migrations private constructor(
+    private val connection: Connection,
+    private val queries: MutableMap<String, Query> = mutableMapOf(),
     private val functions: MutableMap<String, Function> = mutableMapOf()
-    private var initialized = false
-
-    init {
+) {
+    constructor(directory: File, connection: Connection): this(connection) {
         initDB()
         getMigrationFromDB()
         getMigrationFromDirectory(directory)
@@ -52,6 +52,8 @@ class Migrations(directory: File, private val connection: Connection) {
         }
     }
 
+    private var initialized = false
+
     /**
      * Get all migration from DB
      */
@@ -103,7 +105,9 @@ class Migrations(directory: File, private val connection: Connection) {
     }
 
     enum class Direction { UP, DOWN }
-    class DownMigrationNotDefined(path: String, cause: FileNotFoundException): Throwable("The file $path whas not found", cause)
+
+    internal class DownMigrationNotDefined(path: String, cause: FileNotFoundException):
+        Throwable("The file $path whas not found", cause)
 
     fun addFunction(definition: DefinitionFunction, callback: (Function) -> Unit = {}): Migrations {
         if (functions[definition.name] === null) {
@@ -232,7 +236,11 @@ class Migrations(directory: File, private val connection: Connection) {
         return list.toMap()
     }
 
-    fun test(): Map<Pair<String, Direction>, Status> {
+    fun runDry(): Map<Pair<String, Direction>, Status> {
+        return this.copy().runTest()
+    }
+
+    private fun runTest(): Map<Pair<String, Direction>, Status> {
         val list: MutableMap<Pair<String, Direction>, Status> = mutableMapOf()
         connection.connect().apply {
             sendQuery("BEGIN").join()
@@ -248,6 +256,18 @@ class Migrations(directory: File, private val connection: Connection) {
         return list.toMap()
     }
 
+    fun copy(): Migrations {
+        val queriesCopy = queries.map {
+            it.key to it.value.copy()
+        }.toMap().toMutableMap()
+
+        val functionsCopy = functions.map {
+            it.key to it.value.copy()
+        }.toMap().toMutableMap()
+
+        return Migrations(connection, queriesCopy, functionsCopy)
+    }
+
     fun status(): Map<String, Int> {
         TODO("not implemented")
     }
diff --git a/src/main/kotlin/fr/postgresjson/migration/Query.kt b/src/main/kotlin/fr/postgresjson/migration/Query.kt
index 0e0d7cf..7a16b22 100644
--- a/src/main/kotlin/fr/postgresjson/migration/Query.kt
+++ b/src/main/kotlin/fr/postgresjson/migration/Query.kt
@@ -6,7 +6,7 @@ import fr.postgresjson.migration.Migration.Action
 import java.io.File
 import java.util.*
 
-class Query(
+data class Query(
     val name: String,
     val up: String,
     val down: String,
@@ -57,4 +57,10 @@ class Query(
 
         return Migration.Status.OK // TODO
     }
+
+    fun copy(): Query {
+        return this.copy(name = name, up = up, down = down, connection = connection, executedAt = executedAt).also {
+            it.doExecute = this.doExecute
+        }
+    }
 }
\ No newline at end of file
diff --git a/src/test/kotlin/fr/postgresjson/MigrationTest.kt b/src/test/kotlin/fr/postgresjson/MigrationTest.kt
index 0b5bc4b..061781a 100644
--- a/src/test/kotlin/fr/postgresjson/MigrationTest.kt
+++ b/src/test/kotlin/fr/postgresjson/MigrationTest.kt
@@ -13,7 +13,7 @@ import java.io.File
 @TestInstance(TestInstance.Lifecycle.PER_CLASS)
 class MigrationTest(): TestAbstract() {
     @Test
-    fun upQuery() {
+    fun `run up query`() {
         val resources = File(this::class.java.getResource("/sql/migrations").toURI())
         val m = Migrations(resources, getConnextion())
         m.up().apply {
@@ -33,7 +33,7 @@ class MigrationTest(): TestAbstract() {
     }
 
     @Test
-    fun downQuery() {
+    fun `run forced down query`() {
         val resources = File(this::class.java.getResource("/sql/migrations").toURI())
         val m = Migrations(resources, getConnextion())
         repeat(3) {
@@ -45,18 +45,27 @@ class MigrationTest(): TestAbstract() {
     }
 
     @Test
-    fun `test up and down migrations`() {
+    fun `run dry migrations`() {
         val resources = File(this::class.java.getResource("/sql/real_migrations").toURI())
         Migrations(resources, getConnextion()).apply {
-            test().size `should be equal to` 2
+            runDry().size `should be equal to` 2
         }
         Migrations(resources, getConnextion()).apply {
-            test().size `should be equal to` 2
+            runDry().size `should be equal to` 2
         }
     }
 
     @Test
-    fun `test run migrations`() {
+    fun `run dry migrations launch twice`() {
+        val resources = File(this::class.java.getResource("/sql/real_migrations").toURI())
+        Migrations(resources, getConnextion()).apply {
+            runDry().size `should be equal to` 2
+            runDry().size `should be equal to` 2
+        }
+    }
+
+    @Test
+    fun `run migrations`() {
         val resources = File(this::class.java.getResource("/sql/real_migrations").toURI())
         Migrations(resources, getConnextion()).apply {
             run().apply {