Handle when error is not a pqerror

```
panic: interface conversion: error is *net.OpError, not *pq.Error [recovered]
   panic: interface conversion: error is *net.OpError, not *pq.Error
```

Author: halkeye

go.mod

@@ -26,6 +26,7 @@ require (
 	github.com/Azure/go-autorest/autorest/date v0.2.0 // indirect
 	github.com/Azure/go-autorest/logger v0.1.0 // indirect
 	github.com/Azure/go-autorest/tracing v0.5.0 // indirect
+	github.com/DATA-DOG/go-sqlmock v1.5.2 // indirect
 	github.com/PuerkitoBio/purell v1.1.1 // indirect
 	github.com/PuerkitoBio/urlesc v0.0.0-20170810143723-de5bf2ad4578 // indirect
 	github.com/beorn7/perks v1.0.1 // indirect

go.sum

@@ -50,6 +50,8 @@ github.com/BurntSushi/toml v0.3.1 h1:WXkYYl6Yr3qBf1K79EBnL4mak0OimBfB0XUf9Vl28OQ
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
 github.com/DATA-DOG/go-sqlmock v1.4.1/go.mod h1:f/Ixk793poVmq4qj/V1dPUg2JEAKC73Q5eFN3EC/SaM=
+github.com/DATA-DOG/go-sqlmock v1.5.2 h1:OcvFkGmslmlZibjAjaHm3L//6LiuBgolP7OputlJIzU=
+github.com/DATA-DOG/go-sqlmock v1.5.2/go.mod h1:88MAG/4G7SMwSE3CeA0ZKzrT5CiOU3OJ+JlNzwDqpNU=
 github.com/DataDog/datadog-go v3.2.0+incompatible/go.mod h1:LButxg5PwREeZtORoXG3tL4fMGNddJ+vMq1mwgfaqoQ=
 github.com/MakeNowJust/heredoc v0.0.0-20170808103936-bb23615498cd/go.mod h1:64YHyfSL2R96J44Nlwm39UHepQbyR5q10x7iYa1ks2E=
 github.com/Masterminds/goutils v1.1.0/go.mod h1:8cTjp+g8YejhMuvIA5y2vz3BpJxksy863GQaJW2MFNU=
@@ -517,6 +519,7 @@ github.com/kardianos/osext v0.0.0-20190222173326-2bc1f35cddc0/go.mod h1:1NbS8ALr
 github.com/kisielk/errcheck v1.1.0/go.mod h1:EZBBE59ingxPouuu3KfxchcWSUPOHkagtvWXihfKN4Q=
 github.com/kisielk/errcheck v1.2.0/go.mod h1:/BMXB+zMLi60iA8Vv6Ksmxu/1UDYcXs4uQLJ+jE2L00=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
+github.com/kisielk/sqlstruct v0.0.0-20201105191214-5f3e10d3ab46/go.mod h1:yyMNCyc/Ib3bDTKd379tNMpB/7/H5TjM2Y9QJ5THLbE=
 github.com/konsorten/go-windows-terminal-sequences v1.0.1/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/konsorten/go-windows-terminal-sequences v1.0.2/go.mod h1:T0+1ngSBFLxvqU3pZ+m/2kptfBszLMUkC4ZK/EgS/cQ=
 github.com/kr/logfmt v0.0.0-20140226030751-b84e30acd515/go.mod h1:+0opPa2QZZtGFBFZlji/RkVcI2GknAs/DXo4wKdlNEc=

pkg/postgres/role.go

@@ -19,10 +19,30 @@ const (
 	REASIGN_OBJECTS     = `REASSIGN OWNED BY "%s" TO "%s"`
 )
 
+func isPQError(err error, codes ...pq.ErrorCode) bool {
+	if err == nil {
+		return false
+	}
+
+	pgError, ok := err.(*pq.Error)
+	if ok {
+		if len(codes) == 0 {
+			// just checking if its a pgerror
+			return true
+		}
+		for _, code := range codes {
+			if pgError.Code == code {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 func (c *pg) CreateGroupRole(role string) error {
 	// Error code 42710 is duplicate_object (role already exists)
 	_, err := c.db.Exec(fmt.Sprintf(CREATE_GROUP_ROLE, role))
-	if err != nil && err.(*pq.Error).Code != "42710" {
+	if err != nil && !isPQError(err, "42710") {
 		return err
 	}
 	return nil
@@ -64,7 +84,7 @@ func (c *pg) DropRole(role, newOwner, database string, logger logr.Logger) error
 	// REASSIGN OWNED BY only works if the correct database is selected
 	tmpDb, err := GetConnection(c.user, c.pass, c.host, c.port, database, c.args, logger)
 	if err != nil {
-		if err.(*pq.Error).Code == "3D000" {
+		if isPQError(err, "3D000") {
 			return nil // Database is does not exist (anymore)
 		} else {
 			return err
@@ -73,20 +93,20 @@ func (c *pg) DropRole(role, newOwner, database string, logger logr.Logger) error
 	_, err = tmpDb.Exec(fmt.Sprintf(REASIGN_OBJECTS, role, newOwner))
 	defer tmpDb.Close()
 	// Check if error exists and if different from "ROLE NOT FOUND" => 42704
-	if err != nil && err.(*pq.Error).Code != "42704" {
+	if err != nil && isPQError(err, "42704") {
 		return err
 	}
 
 	// We previously assigned all objects to the operator's role so DROP OWNED BY will drop privileges of role
 	_, err = tmpDb.Exec(fmt.Sprintf(DROP_OWNED_BY, role))
 	// Check if error exists and if different from "ROLE NOT FOUND" => 42704
-	if err != nil && err.(*pq.Error).Code != "42704" {
+	if err != nil && isPQError(err, "42704") {
 		return err
 	}
 
 	_, err = c.db.Exec(fmt.Sprintf(DROP_ROLE, role))
 	// Check if error exists and if different from "ROLE NOT FOUND" => 42704
-	if err != nil && err.(*pq.Error).Code != "42704" {
+	if err != nil && isPQError(err, "42704") {
 		return err
 	}
 	return nil

pkg/postgres/role_test.go

@@ -0,0 +1,70 @@
+package postgres
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/DATA-DOG/go-sqlmock"
+	"github.com/lib/pq"
+)
+
+func TestIsPQError(t *testing.T) {
+	genericError := errors.New("regular error")
+
+	pqError := new(pq.Error)
+	pqError.Code = "42710"
+
+	if isPQError(genericError, "42710") {
+		t.Fatalf("generic error is not an pq error")
+	}
+
+	if isPQError(pqError, "111111") {
+		t.Fatalf("might be a pq error, but isn't this specific one")
+	}
+
+	if !isPQError(pqError, "42710") {
+		t.Fatalf("should match targeted pqerror")
+	}
+
+	// multiple
+	if !isPQError(pqError, "42710", "111111") {
+		t.Fatalf("should match targeted pqerror")
+	}
+}
+
+func TestCreateGroupRole(t *testing.T) {
+	db, mock, err := sqlmock.New()
+	if err != nil {
+		t.Fatalf("an error '%s' was not expected when opening a stub database connection", err)
+	}
+
+	defer db.Close()
+
+	duplicateObjectPGError := new(pq.Error)
+	duplicateObjectPGError.Code = "42710" // duplicate_object
+
+	diskFullError := new(pq.Error)
+	diskFullError.Code = "53100" // disk_full
+
+	mock.ExpectExec(`CREATE ROLE "working"`).WillReturnResult(sqlmock.NewResult(1, 1))
+	mock.ExpectExec(`CREATE ROLE "already-exists"`).WillReturnError(duplicateObjectPGError)
+	mock.ExpectExec(`CREATE ROLE "disk-full"`).WillReturnError(diskFullError)
+
+	pgObj := &pg{db: db}
+	if err := pgObj.CreateGroupRole("working"); err != nil {
+		t.Errorf("error calling create role: %s", err)
+	}
+
+	if err := pgObj.CreateGroupRole("already-exists"); err != nil {
+		t.Errorf("error calling create role: %s", err)
+	}
+
+	if err := pgObj.CreateGroupRole("disk-full"); err == nil {
+		t.Errorf("non ignored error didn't throw error")
+	}
+
+	// we make sure that all expectations were met
+	if err := mock.ExpectationsWereMet(); err != nil {
+		t.Errorf("there were unfulfilled expectations: %s", err)
+	}
+}