Clarify check_mysql test prompts

Also default to "-u test -ptest" which are default MySQL accounts only
missing the prescribed privileges.

The database is no longer specified as it is not used.
If wanted is should be its own parameter/tests.

plugins/t/check_mysql.t

@@ -21,27 +21,29 @@ plan skip_all => "check_mysql not compiled" unless (-x "check_mysql");
 plan tests => 15;
 
 my $bad_login_output = '/Access denied for user /';
-my $mysqlserver = getTestParameter( 
-		"NP_MYSQL_SERVER", 
+my $mysqlserver = getTestParameter(
+		"NP_MYSQL_SERVER",
 		"A MySQL Server hostname or IP with no slaves setup"
 		);
-my $mysqlsocket = getTestParameter( 
-		"NP_MYSQL_SOCKET", 
-		"A MySQL Server socket with no slaves setup"
+my $mysqlsocket = getTestParameter(
+		"NP_MYSQL_SOCKET",
+		"Full path to a MySQL Server socket with no slaves setup"
 		);
-my $mysql_login_details = getTestParameter( 
-		"MYSQL_LOGIN_DETAILS", 
-		"Command line parameters to specify login access",
-		"-u user -ppw -d db",
+my $mysql_login_details = getTestParameter(
+		"MYSQL_LOGIN_DETAILS",
+		"Command line parameters to specify login access (requires " .
+		"REPLICATION CLIENT privleges)",
+		"-u test -ptest",
 		);
-my $with_slave = getTestParameter( 
-		"NP_MYSQL_WITH_SLAVE", 
+my $with_slave = getTestParameter(
+		"NP_MYSQL_WITH_SLAVE",
 		"MySQL server with slaves setup"
 		);
-my $with_slave_login = getTestParameter( 
-		"NP_MYSQL_WITH_SLAVE_LOGIN", 
-		"Login details for server with slave", 
-		"-uroot -ppw"
+my $with_slave_login = getTestParameter(
+		"NP_MYSQL_WITH_SLAVE_LOGIN",
+		"Login details for server with slave (requires REPLICATION CLIENT " .
+		"privleges)",
+		$mysql_login_details || "-u test -ptest"
 		);
 
 my $result;