Moved merge tests from main to suite/merge

This makes it easier to run test on just the MRG_MYISAM engine.

Other things:
- Renamed merge-big.test to flush_corruption.test as it does not
  have anything to do with merge tables.

mysql-test/main/alter_table.result

@@ -268,28 +268,6 @@ ERROR 42000: Incorrect table name ''
 rename table t1 to ``;
 ERROR 42000: Incorrect table name ''
 drop table t1;
-drop table if exists t1, t2;
-Warnings:
-Note	1051	Unknown table 'test.t1,test.t2'
-create table t1 ( a varchar(10) not null primary key ) engine=myisam;
-create table t2 ( a varchar(10) not null primary key ) engine=merge union=(t1);
-flush tables;
-alter table t1 modify a varchar(10);
-show create table t2;
-Table	Create Table
-t2	CREATE TABLE `t2` (
-  `a` varchar(10) NOT NULL,
-  PRIMARY KEY (`a`)
-) ENGINE=MRG_MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci UNION=(`t1`)
-flush tables;
-alter table t1 modify a varchar(10) not null;
-show create table t2;
-Table	Create Table
-t2	CREATE TABLE `t2` (
-  `a` varchar(10) NOT NULL,
-  PRIMARY KEY (`a`)
-) ENGINE=MRG_MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci UNION=(`t1`)
-drop table if exists t1, t2;
 create table t1 (a int, b int, c int, d int, e int, f int, g int, h int,i int, primary key (a,b,c,d,e,f,g,i,h)) engine=MyISAM;
 insert ignore into t1 (a) values(1);
 Warnings:

mysql-test/main/alter_table.test

@@ -244,20 +244,6 @@ alter table t1 rename to ``;
 rename table t1 to ``;
 drop table t1;
 
-#
-# BUG#6236 - ALTER TABLE MODIFY should set implicit NOT NULL on PK columns
-#
-drop table if exists t1, t2;
-create table t1 ( a varchar(10) not null primary key ) engine=myisam;
-create table t2 ( a varchar(10) not null primary key ) engine=merge union=(t1);
-flush tables;
-alter table t1 modify a varchar(10);
-show create table t2;
-flush tables;
-alter table t1 modify a varchar(10) not null;
-show create table t2;
-drop table if exists t1, t2;
-
 # The following is also part of bug #6236 (CREATE TABLE didn't properly count
 # not null columns for primary keys)
 

mysql-test/main/flush_corruption.test

@@ -1,5 +1,5 @@
 #
-# Test of MERGE tables with multisession and many waits.
+# Test of MyISAM tables with multisession and many waits.
 #
 # This test takes rather long time so let us run it only in --big-test mode
 --source include/big_test.inc

mysql-test/mariadb-test-run.pl

@@ -200,6 +200,7 @@ my @DEFAULT_SUITES= qw(
     json-
     maria-
     mariabackup-
+    merge-
     multi_source-
     optimizer_unfixed_bugs-
     parts-

mysql-test/suite/merge/alter_table.result

@@ -0,0 +1,22 @@
+#
+# BUG#6236 - ALTER TABLE MODIFY should set implicit NOT NULL on PK columns
+#
+create table t1 ( a varchar(10) not null primary key ) engine=myisam;
+create table t2 ( a varchar(10) not null primary key ) engine=merge union=(t1);
+flush tables;
+alter table t1 modify a varchar(10);
+show create table t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `a` varchar(10) NOT NULL,
+  PRIMARY KEY (`a`)
+) ENGINE=MRG_MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci UNION=(`t1`)
+flush tables;
+alter table t1 modify a varchar(10) not null;
+show create table t2;
+Table	Create Table
+t2	CREATE TABLE `t2` (
+  `a` varchar(10) NOT NULL,
+  PRIMARY KEY (`a`)
+) ENGINE=MRG_MyISAM DEFAULT CHARSET=latin1 COLLATE=latin1_swedish_ci UNION=(`t1`)
+drop table if exists t1, t2;

mysql-test/suite/merge/alter_table.test

@@ -0,0 +1,12 @@
+--echo #
+--echo # BUG#6236 - ALTER TABLE MODIFY should set implicit NOT NULL on PK columns
+--echo #
+create table t1 ( a varchar(10) not null primary key ) engine=myisam;
+create table t2 ( a varchar(10) not null primary key ) engine=merge union=(t1);
+flush tables;
+alter table t1 modify a varchar(10);
+show create table t2;
+flush tables;
+alter table t1 modify a varchar(10) not null;
+show create table t2;
+drop table if exists t1, t2;