pool: implemented Role Stringer interface

[KaymeKaydex]

implemented Role Stringer interface for human-readable printing

Closes: #405

[oleg-jukovec]

I suggest to use stringer (go install golang.org/x/tools/cmd/stringer@latest) + go generate instead of a custom code.

diff --git a/pool/const.go b/pool/const.go
index 7ec239f..22bff4f 100644
--- a/pool/const.go
+++ b/pool/const.go
@@ -30,8 +30,12 @@ const (
 // Role describes a role of an instance by its mode.
 type Role uint32
 
+//go:generate stringer -type Role -linecomment
 const (
-    UnknownRole Role = iota // A connection pool failed to discover mode of the instance.
-    MasterRole              // The instance is read-write mode.
-    ReplicaRole             // The instance is in read-only mode.
+    // A connection pool failed to discover mode of the instance.
+    UnknownRole Role = iota // unknown
+    // The instance is read-write mode.
+    MasterRole              // master
+    // The instance is in read-only mode.
+    ReplicaRole             // replica
 )

[KaymeKaydex]

@oleg-jukovec i generated Stringer face by stringer library. since it can only cut prefixes, I was forced to rename the roles, since they are not specified externally, this will not change the user interface

[oleg-jukovec]

@oleg-jukovec i generated Stringer face by stringer library. since it can only cut prefixes, I was forced to rename the roles, since they are not specified externally, this will not change the user interface

Unfortunately, we could not change naming because it will break backward compatibility.

But the ‘stringer’ could generate custom strings, see ‘-linecomment’ option for the ‘stringer’ and my patch more carefully.

[KaymeKaydex]

i will open new pr instead amend fixes

[oleg-jukovec]

Please, fix red tests.

[DerekBum]

Thank you for the patch! Please see couple of nits below.

Also, don't forget to squash the commits after the work is done. And please change the line Related issues: #405 to the Closes #405, so the issue could be closed automatically after the merge.

[KaymeKaydex]

@DerekBum thanks, I accepted the proposed changes and squashed all commits

[DerekBum]

Thanks for the patch!