Use errors.Is() in templates (#3736)

* Use errors.Is() in templates

* Update http/codegen/templates/client_sse.go.tpl

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

---------

Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>

Author: tchssk

codegen/example/templates/client_endpoint_init.go.tpl

@@ -16,7 +16,7 @@
 		}
 	}
 	if err != nil {
-		if err == flag.ErrHelp {
+		if errors.Is(err, flag.ErrHelp) {
 			os.Exit(0)
 		}
 		fmt.Fprintln(os.Stderr, err.Error())

codegen/example/testdata/client-no-server.golden

@@ -61,7 +61,7 @@ func main() {
 		}
 	}
 	if err != nil {
-		if err == flag.ErrHelp {
+		if errors.Is(err, flag.ErrHelp) {
 			os.Exit(0)
 		}
 		fmt.Fprintln(os.Stderr, err.Error())

codegen/example/testdata/client-single-server-multiple-hosts-with-variables.golden

@@ -80,7 +80,7 @@ func main() {
 		}
 	}
 	if err != nil {
-		if err == flag.ErrHelp {
+		if errors.Is(err, flag.ErrHelp) {
 			os.Exit(0)
 		}
 		fmt.Fprintln(os.Stderr, err.Error())

codegen/example/testdata/client-single-server-multiple-hosts.golden

@@ -61,7 +61,7 @@ func main() {
 		}
 	}
 	if err != nil {
-		if err == flag.ErrHelp {
+		if errors.Is(err, flag.ErrHelp) {
 			os.Exit(0)
 		}
 		fmt.Fprintln(os.Stderr, err.Error())

codegen/example/testdata/client-single-server-single-host-with-variables.golden

@@ -77,7 +77,7 @@ func main() {
 		}
 	}
 	if err != nil {
-		if err == flag.ErrHelp {
+		if errors.Is(err, flag.ErrHelp) {
 			os.Exit(0)
 		}
 		fmt.Fprintln(os.Stderr, err.Error())

codegen/example/testdata/client-single-server-single-host.golden

@@ -61,7 +61,7 @@ func main() {
 		}
 	}
 	if err != nil {
-		if err == flag.ErrHelp {
+		if errors.Is(err, flag.ErrHelp) {
 			os.Exit(0)
 		}
 		fmt.Fprintln(os.Stderr, err.Error())

http/codegen/templates/client_sse.go.tpl

@@ -29,10 +29,10 @@ func (s *{{ .Method.VarName }}StreamImpl) RecvWithContext(ctx context.Context) (
 	var byts []byte
 	byts, err = s.readEvent(ctx)
 	if err != nil {
-		if err == io.EOF || err == context.Canceled || err == context.DeadlineExceeded {
+		if errors.Is(err, io.EOF) || errors.Is(err, context.Canceled) || errors.Is(err, context.DeadlineExceeded) {
 			// Clean up on EOF or context cancellation
 			s.Close()
-			if err == io.EOF {
+			if errors.Is(err, io.EOF) {
 				err = nil
 			}
 		}
@@ -117,7 +117,7 @@ func (s *{{ .Method.VarName }}StreamImpl) readEvent(ctx context.Context) ([]byte
 		}
 
 		// Return partial data at EOF
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			if len(eventData) > 0 {
 				return eventData, nil
 			}

http/codegen/templates/partial/request_elements.go.tpl

@@ -296,7 +296,7 @@ qp := r.URL.Query()
 {{- range .Cookies }}
 	c, {{ if not .Required }}_{{ else }}err{{ end }} = r.Cookie("{{ .HTTPName }}")
 	{{- if and (or (eq .Type.Name "string") (eq .Type.Name "any")) .Required }}
-		if err == http.ErrNoCookie {
+		if errors.Is(err, http.ErrNoCookie) {
 			err = goa.MergeErrors(err, goa.MissingFieldError("{{ .Name }}", "cookie"))
 		} else {
 			{{ .VarName }} = c.Value

http/codegen/templates/request_decoder.go.tpl

@@ -18,11 +18,11 @@ func {{ .RequestDecoder }}(mux goahttp.Muxer, decoder func(*http.Request) goahtt
 		err = decoder(r).Decode(&body)
 		if err != nil {
 	{{- if .Payload.Request.MustHaveBody }}
-			if err == io.EOF {
+			if errors.Is(err, io.EOF) {
 				return nil, goa.MissingPayloadError()
 			}
 	{{- else }}
-			if err == io.EOF {
+			if errors.Is(err, io.EOF) {
 				err = nil
 			} else {
 	{{- end }}