error cleanup

dialog.go

@@ -3,7 +3,6 @@ package slack
 import (
 	"context"
 	"encoding/json"
-	"errors"
 )
 
 // InputType is the type of the dialog input type
@@ -89,7 +88,7 @@ func (api *Client) OpenDialog(triggerID string, dialog Dialog) (err error) {
 // EXPERIMENTAL: dialog functionality is currently experimental, api is not considered stable.
 func (api *Client) OpenDialogContext(ctx context.Context, triggerID string, dialog Dialog) (err error) {
 	if triggerID == "" {
-		return errors.New("received empty parameters")
+		return ErrParametersMissing
 	}
 
 	req := DialogTrigger{

errors.go

@@ -0,0 +1,17 @@
+package slack
+
+import "github.com/nlopes/slack/internal/errorsx"
+
+// Errors returned by various methods.
+const (
+	ErrAlreadyDisconnected  = errorsx.String("Invalid call to Disconnect - Slack API is already disconnected")
+	ErrParametersMissing    = errorsx.String("received empty parameters")
+	ErrInvalidConfiguration = errorsx.String("invalid configuration")
+	ErrMissingHeaders       = errorsx.String("missing headers")
+	ErrExpiredTimestamp     = errorsx.String("timestamp is too old")
+)
+
+// internal errors
+const (
+	errPaginationComplete = errorsx.String("pagination complete")
+)

files.go

@@ -2,7 +2,6 @@ package slack
 
 import (
 	"context"
-	"errors"
 	"fmt"
 	"io"
 	"net/url"
@@ -292,7 +291,7 @@ func (api *Client) DeleteFileComment(commentID, fileID string) error {
 // DeleteFileCommentContext deletes a file's comment with a custom context
 func (api *Client) DeleteFileCommentContext(ctx context.Context, fileID, commentID string) (err error) {
 	if fileID == "" || commentID == "" {
-		return errors.New("received empty parameters")
+		return ErrParametersMissing
 	}
 
 	values := url.Values{

internal/errorsx/errorsx.go

@@ -0,0 +1,8 @@
+package errorsx
+
+// String representing an error, useful for declaring string constants as errors.
+type String string
+
+func (t String) Error() string {
+	return string(t)
+}

misc.go

@@ -265,12 +265,6 @@ func okJSONHandler(rw http.ResponseWriter, r *http.Request) {
 	rw.Write(response)
 }
 
-type errorString string
-
-func (t errorString) Error() string {
-	return string(t)
-}
-
 // timerReset safely reset a timer, see time.Timer.Reset for details.
 func timerReset(t *time.Timer, d time.Duration) {
 	if !t.Stop() {

security.go

@@ -4,7 +4,6 @@ import (
 	"crypto/hmac"
 	"crypto/sha256"
 	"encoding/hex"
-	"errors"
 	"fmt"
 	"hash"
 	"net/http"
@@ -34,7 +33,7 @@ func unsafeSignatureVerifier(header http.Header, secret string) (_ SecretsVerifi
 	stimestamp := header.Get(hTimestamp)
 
 	if signature == "" || stimestamp == "" {
-		return SecretsVerifier{}, errors.New("missing headers")
+		return SecretsVerifier{}, ErrMissingHeaders
 	}
 
 	if bsignature, err = hex.DecodeString(strings.TrimPrefix(signature, "v0=")); err != nil {
@@ -70,7 +69,7 @@ func NewSecretsVerifier(header http.Header, secret string) (sv SecretsVerifier,
 
 	diff := absDuration(time.Since(time.Unix(timestamp, 0)))
 	if diff > 5*time.Minute {
-		return SecretsVerifier{}, fmt.Errorf("timestamp is too old")
+		return SecretsVerifier{}, ErrExpiredTimestamp
 	}
 
 	return sv, err

users.go

@@ -12,7 +12,6 @@ const (
 	DEFAULT_USER_PHOTO_CROP_X = -1
 	DEFAULT_USER_PHOTO_CROP_Y = -1
 	DEFAULT_USER_PHOTO_CROP_W = -1
-	errPaginationComplete     = errorString("pagination complete")
 )
 
 // UserProfile contains all the information details of a given user