Return of errors was removed from Image(), Solve(), IsSolved(), and Remove() methods.

internal/handlers/handlers.go

@@ -11,9 +11,7 @@ import (
 	"time"
 )
 
-const errMsgNotFound = "CAPTCHA with such ID doesn't exist"
 const errMsgWrongAnswer = "An answer provided was wrong"
-const errMsgFailedToGenImage = "failed to generate an image for a CAPTCHA"
 const errMsgImageNotFound = "cannot get an image for a non-existing CAPTCHA"
 
 type CaptchaHandlers struct {
@@ -36,14 +34,9 @@ func (h *CaptchaHandlers) Image(w http.ResponseWriter, r *http.Request) {
 	captchaID := captcha.ID(server.GetURLParam(r, "captcha"))
 	captchaStyle := r.URL.Query().Get("style")
 
-	captchaImage, err := inmemdb.Image(captchaID, captchaStyle)
+	captchaImage := inmemdb.Image(captchaID, captchaStyle)
-	if err != nil {
-		http.Error(w, errMsgImageNotFound, http.StatusNotFound)
-		return
-	}
-
 	if captchaImage == nil {
-		http.Error(w, errMsgFailedToGenImage, http.StatusInternalServerError)
+		http.Error(w, errMsgImageNotFound, http.StatusNotFound)
 		return
 	}
 
@@ -58,13 +51,7 @@ func (h *CaptchaHandlers) Solve(w http.ResponseWriter, r *http.Request) {
 	r.ParseForm()
 	answer := captcha.Answer(r.FormValue("answer"))
 
-	ok, err := inmemdb.Solve(captchaID, answer)
+	if ok := inmemdb.Solve(captchaID, answer); !ok {
-	if err != nil {
-		http.Error(w, errMsgNotFound, http.StatusNotFound)
-		return
-	}
-
-	if !ok {
 		http.Error(w, errMsgWrongAnswer, http.StatusForbidden)
 		return
 	}
@@ -82,14 +69,9 @@ func (h *CaptchaHandlers) IsSolved(w http.ResponseWriter, r *http.Request) {
 		return
 	}
 
-	solved, err := inmemdb.IsSolved(captchaID)
+	if solved := inmemdb.IsSolved(captchaID); !solved {
-	if err != nil {
-		http.Error(w, errMsgNotFound, http.StatusNotFound)
-		return
-	}
-
-	if !solved {
 		http.Error(w, errMsgWrongAnswer, http.StatusForbidden)
+		return
 	}
 
 	w.WriteHeader(http.StatusNoContent)

pkg/captcha/db.go

@@ -4,14 +4,11 @@ import (
 	"crypto/rand"
 	"crypto/sha256"
 	"encoding/base64"
-	"errors"
 	"image"
 	"strconv"
 	"time"
 )
 
-var ErrorNotFound = errors.New("captcha not found")
-
 const DefaultExpiredScanInterval = 60 * time.Second
 
 // ID is a CAPTCHA identifier.

pkg/captcha/inmemdb/inmemdb.go

@@ -61,18 +61,18 @@ func (imcdb *InMemoryCaptchaDB) SetExpiry(expiry time.Duration) {
 }
 
 // Image returns a freshly generated image for a CAPTCHA.
-func (imcdb *InMemoryCaptchaDB) Image(id captcha.ID, style string) (*image.Image, error) {
+func (imcdb *InMemoryCaptchaDB) Image(id captcha.ID, style string) *image.Image {
 	imcdb.Lock()
 	defer imcdb.Unlock()
 	if c, ok := imcdb.db[id]; ok {
-		return c.Image(style), nil
+		return c.Image(style)
 	}
-	return nil, captcha.ErrorNotFound
+	return nil
 }
 
 // Solve compares given answer with a stored one and if failed
 // deletes a CAPTCHA from database.
-func (imcdb *InMemoryCaptchaDB) Solve(id captcha.ID, answer captcha.Answer) (bool, error) {
+func (imcdb *InMemoryCaptchaDB) Solve(id captcha.ID, answer captcha.Answer) bool {
 	imcdb.Lock()
 	defer imcdb.Unlock()
 	if c, ok := imcdb.db[id]; ok {
@@ -80,32 +80,30 @@ func (imcdb *InMemoryCaptchaDB) Solve(id captcha.ID, answer captcha.Answer) (boo
 		if !ok {
 			delete(imcdb.db, id)
 		}
-		return ok, nil
+		return ok
 	}
-	return false, captcha.ErrorNotFound
+	return false
 }
 
 // IsSolved checks if CAPTCHA was solved and removes it
 // from a database.
-func (imcdb *InMemoryCaptchaDB) IsSolved(id captcha.ID) (bool, error) {
+func (imcdb *InMemoryCaptchaDB) IsSolved(id captcha.ID) bool {
 	imcdb.Lock()
 	defer imcdb.Unlock()
 	if c, ok := imcdb.db[id]; ok {
 		delete(imcdb.db, id)
-		return c.IsSolved(), nil
+		return c.IsSolved()
 	}
-	return false, captcha.ErrorNotFound
+	return false
 }
 
 // Remove a CAPTCHA from a database.
-func (imcdb *InMemoryCaptchaDB) Remove(id captcha.ID) error {
+func (imcdb *InMemoryCaptchaDB) Remove(id captcha.ID) {
 	imcdb.Lock()
 	defer imcdb.Unlock()
 	if _, ok := imcdb.db[id]; ok {
 		delete(imcdb.db, id)
-		return nil
 	}
-	return captcha.ErrorNotFound
 }
 
 // cleanExpired removes expired CAPTCHAs in a loop.
@@ -140,18 +138,18 @@ func New(data string, captcha captcha.Captcha) (captcha.Captcha, captcha.ID) {
 	return imcdb.New(data, captcha)
 }
 
-func Image(id captcha.ID, style string) (*image.Image, error) {
+func Image(id captcha.ID, style string) *image.Image {
 	return imcdb.Image(id, style)
 }
 
-func Solve(id captcha.ID, answer captcha.Answer) (bool, error) {
+func Solve(id captcha.ID, answer captcha.Answer) bool {
 	return imcdb.Solve(id, answer)
 }
 
-func IsSolved(id captcha.ID) (bool, error) {
+func IsSolved(id captcha.ID) bool {
 	return imcdb.IsSolved(id)
 }
 
-func Remove(id captcha.ID) error {
+func Remove(id captcha.ID) {
-	return imcdb.Remove(id)
+	imcdb.Remove(id)
 }