Add reversed actions when using reverse

build.sbt

@@ -21,7 +21,7 @@ libraryDependencies += "org.apache.derby"    % "derby"                % "10.11.1
 
 libraryDependencies += "org.hsqldb"          % "hsqldb"               % "2.5.0"     % "test"
 
-libraryDependencies += "org.postgresql"      % "postgresql"           % "42.2.14"    % "test"
+libraryDependencies += "org.postgresql"      % "postgresql"           % "42.2.14"   % "test"
 
 libraryDependencies += "mysql"               % "mysql-connector-java" % "8.0.16"    % "test"
 

src/main/scala/slick/migration/api/TableMigration.scala

@@ -10,27 +10,27 @@ object TableMigration {
 
   object Action {
     sealed abstract class Reversible(sort: Int) extends Action(sort)
-    case object DropTable extends Action(0)
-    case object CreateTable extends Reversible(1)
-    case class RenameTableTo(to: String) extends Reversible(2)
-    case class RenameTableFrom(from: String) extends Reversible(2)
-    case class AddColumn(info: ColumnInfo) extends Reversible(3)
-    case class AddColumnAndSetInitialValue(info: ColumnInfo, rawSqlExpr: String) extends Reversible(3)
-    case class DropColumn(info: ColumnInfo) extends Reversible(4)
-    case class DropColumnOfName(name: String) extends Action(4)
-    case class RenameColumnTo(originalInfo: ColumnInfo, to: String) extends Reversible(5)
-    case class RenameColumnFrom(currentInfo: ColumnInfo, from: String) extends Reversible(5)
-    case class AlterColumnType(info: ColumnInfo) extends Action(6)
-    case class AlterColumnDefault(info: ColumnInfo) extends Action(6)
-    case class AlterColumnNullable(info: ColumnInfo) extends Action(6)
-    case class DropPrimaryKey(info: PrimaryKeyInfo) extends Reversible(7)
-    case class DropForeignKey(fk: ForeignKey) extends Reversible(7)
+    case object CreateTable extends Reversible(0)
+    case class RenameTableTo(to: String) extends Reversible(1)
+    case class AddColumn(info: ColumnInfo) extends Reversible(2)
+    case class AddColumnAndSetInitialValue(info: ColumnInfo, rawSqlExpr: String) extends Reversible(2)
+    case class RenameColumnTo(originalInfo: ColumnInfo, to: String) extends Reversible(2)
+    case class AlterColumnType(info: ColumnInfo) extends Action(3)
+    case class AlterColumnDefault(info: ColumnInfo) extends Action(3)
+    case class AlterColumnNullable(info: ColumnInfo) extends Action(3)
+    case class AddPrimaryKey(info: PrimaryKeyInfo) extends Reversible(4)
+    case class AddForeignKey(fk: ForeignKey) extends Reversible(4)
+    case class CreateIndex(info: IndexInfo) extends Reversible(5)
+    case class RenameIndexTo(originalInfo: IndexInfo, to: String) extends Reversible(5)
+    case class DropPrimaryKey(info: PrimaryKeyInfo) extends Reversible(6)
+    case class DropForeignKey(fk: ForeignKey) extends Reversible(6)
     case class DropIndex(info: IndexInfo) extends Reversible(7)
-    case class AddPrimaryKey(info: PrimaryKeyInfo) extends Reversible(8)
-    case class AddForeignKey(fk: ForeignKey) extends Reversible(8)
-    case class CreateIndex(info: IndexInfo) extends Reversible(8)
-    case class RenameIndexTo(originalInfo: IndexInfo, to: String) extends Reversible(9)
-    case class RenameIndexFrom(currentInfo: IndexInfo, from: String) extends Reversible(9)
+    case class RenameColumnFrom(currentInfo: ColumnInfo, from: String) extends Reversible(8)
+    case class RenameIndexFrom(currentInfo: IndexInfo, from: String) extends Reversible(8)
+    case class RenameTableFrom(from: String) extends Reversible(8)
+    case class DropColumnOfName(name: String) extends Action(9)
+    case class DropColumn(info: ColumnInfo) extends Reversible(9)
+    case object DropTable extends Action(10)
   }
 
   sealed trait WithActions[A <: Action] {

src/test/scala/slick/migration/api/DbTest.scala

@@ -7,7 +7,7 @@ import scala.concurrent.Await
 import scala.concurrent.ExecutionContext.Implicits.global
 import scala.concurrent.duration.Duration
 import scala.util.control.NonFatal
-import slick.jdbc.{HsqldbProfile, JdbcProfile, OracleProfile}
+import slick.jdbc.{HsqldbProfile, JdbcProfile, OracleProfile, PostgresProfile}
 import slick.jdbc.meta._
 import slick.lifted.AbstractTable
 import com.typesafe.slick.testkit.util.JdbcTestDB
@@ -245,6 +245,36 @@ abstract class DbTest[P <: JdbcProfile](val tdb: JdbcTestDB {val profile: P})
         runMigration(tm.drop)
     }
   }
+
+  test("reverse") {
+    val tm = TableMigration(TestTable)
+    val createTable = tm.create.addColumns(_.id, _.strWithDefault)
+
+    assert(createTable.sql.size === 1)
+    assert(createTable.sql.head.contains("create table"))
+
+    runMigration(createTable)
+
+    val reversed = createTable.reverse
+
+    assert(reversed.sql.size === 3)
+    assert(reversed.sql.head.contains("ID"))
+    assert(reversed.sql(1).contains("STR_WITH_DEFAULT"))
+    assert(reversed.sql(2).contains("drop table"))
+
+    try withBeforeAndAfter(reversed)(getTables) { (before, after) =>
+      // Only postgres can remove all columns from a table
+      if (this.profile.isInstanceOf[PostgresProfile]) {
+        assert(before.contains("TEST_TABLE"))
+        assert(!after.contains("TEST_TABLE"))
+      }
+    } catch {
+      case _: Throwable =>
+        if (!this.profile.isInstanceOf[PostgresProfile]) {
+          runMigration(tm.drop)
+        }
+    }
+  }
 }
 
 trait CompleteDbTest { this: DbTest[_ <: JdbcProfile] =>