simplify collation tests

Author: methane

driver_test.go

@@ -1610,68 +1610,32 @@ func TestCollation(t *testing.T){
 t.Skipf("MySQL server not running on %s", netAddr)
  }
 
-defaultCollation:="utf8mb4_general_ci"
+// MariaDB may override collation specified by handshake with `character_set_collations` variable.
+// https://mariadb.com/kb/en/setting-character-sets-and-collations/#changing-default-collation
+// https://mariadb.com/kb/en/server-system-variables/#character_set_collations
+// utf8mb4_general_ci, utf8mb3_general_ci will be overridden by default MariaDB.
+// Collations other than charasets default are not overridden. So utf8mb4_unicode_ci is safe.
 testCollations:= []string{
-"", // do not set
-defaultCollation, // driver default
 "latin1_general_ci",
 "binary",
 "utf8mb4_unicode_ci",
 "cp1257_bin",
  }
 
 for_, collation:=rangetestCollations{
-varexpected, tdsnstring
-ifcollation!=""{
-tdsn=dsn+"&collation="+collation
-expected=collation
- } else{
-tdsn=dsn
-expected=defaultCollation
- }
-
-runTests(t, tdsn, func(dbt*DBTest){
-// see https://mariadb.com/kb/en/setting-character-sets-and-collations/#changing-default-collation
-// when character_set_collations is set for the charset, it overrides the default collation
-// so we need to check if the default collation is overridden
-forceExpected:=expected
-vardefaultCollationsstring
-err:=dbt.db.QueryRow("SELECT @@character_set_collations").Scan(&defaultCollations)
-iferr==nil{
-// Query succeeded, need to check if we should override expected collation
-collationMap:=make(map[string]string)
-pairs:=strings.Split(defaultCollations, ",")
-for_, pair:=rangepairs{
-parts:=strings.Split(pair, "=")
-iflen(parts) ==2{
-collationMap[parts[0]] =parts[1]
- }
- }
+t.Run(collation, func(t*testing.T){
+tdsn:=dsn+"&collation="+collation
+expected:=collation
 
-// Get charset prefix from expected collation
-parts:=strings.Split(expected, "_")
-iflen(parts) >0{
-charset:=parts[0]
-ifnewCollation, ok:=collationMap[charset]; ok{
-forceExpected=newCollation
- }
+runTests(t, tdsn, func(dbt*DBTest){
+vargotstring
+iferr:=dbt.db.QueryRow("SELECT @@collation_connection").Scan(&got); err!=nil{
+dbt.Fatal(err)
  }
- }
-
-vargotstring
-iferr:=dbt.db.QueryRow("SELECT @@collation_connection").Scan(&got); err!=nil{
-dbt.Fatal(err)
- }
-
-ifgot!=expected{
-ifforceExpected!=expected{
-ifgot!=forceExpected{
-dbt.Fatalf("expected forced connection collation %s but got %s", forceExpected, got)
- }
- } else{
+ifgot!=expected{
 dbt.Fatalf("expected connection collation %s but got %s", expected, got)
  }
- }
+ })
  })
  }
 }