ci: enable golangci-lint standard checks

.github/workflows/test.yml

@@ -18,3 +18,15 @@ jobs:
           go-version-file: go.mod
           cache: true
       - run: go test -race ./...
+
+  lint:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+      - uses: actions/setup-go@v5
+        with:
+          go-version-file: go.mod
+          cache: true
+      - uses: golangci/golangci-lint-action@v9
+        with:
+          version: v2.13.2

.golangci.yml

@@ -0,0 +1,8 @@
+version: "2"
+
+linters:
+  default: standard
+
+run:
+  tests: true
+  timeout: 5m

README.md

@@ -102,6 +102,9 @@ simulates success, quota errors, service failures, and malformed responses.
 Run just these tests with `go test -race ./google_mail -run TestGmailIntegration`.
 They test our API integration contract, not Google-side permissions or delivery.
 
+Run `golangci-lint run` with golangci-lint v2.13.2 for the same lint checks as
+CI. `.golangci.yml` enables the standard default preset, including test files.
+
 ### Manual
 Use Go 1.27.1, matching `go.mod`, CI, and the Docker build images.
 1. Follow the steps in [Setup](#setup) and enable debug mode.

go.mod

@@ -6,7 +6,6 @@ require (
 	github.com/gocraft/web v0.0.0-20190207150652-9707327fb69b
 	github.com/spf13/viper v1.20.0
 	github.com/stretchr/testify v1.10.0
-	golang.org/x/net v0.37.0
 	golang.org/x/oauth2 v0.28.0
 	google.golang.org/api v0.227.0
 )
@@ -41,6 +40,7 @@ require (
 	go.uber.org/atomic v1.9.0 // indirect
 	go.uber.org/multierr v1.9.0 // indirect
 	golang.org/x/crypto v0.36.0 // indirect
+	golang.org/x/net v0.37.0 // indirect
 	golang.org/x/sys v0.31.0 // indirect
 	golang.org/x/text v0.23.0 // indirect
 	google.golang.org/genproto/googleapis/rpc v0.0.0-20250313205543-e70fdf4c4cb4 // indirect

google_mail/google_service.go

@@ -6,7 +6,7 @@ import (
 	"google.golang.org/api/gmail/v1" // Imports as gmail
 	"google.golang.org/api/option"
 
-	"golang.org/x/net/context"
+	"context"
 	"golang.org/x/oauth2/google"
 
 	"encoding/base64"

google_mail/integration_test.go

@@ -111,7 +111,7 @@ func TestGmailIntegration(t *testing.T) {
 			client := &http.Client{Timeout: 5 * time.Second}
 			response, err := client.Do(req)
 			require.NoError(t, err)
-			defer response.Body.Close()
+			defer func() { assert.NoError(t, response.Body.Close()) }()
 			assert.Equal(t, tc.wantStatus, response.StatusCode)
 			select {
 			case assertion := <-assertions:

web/mail.go

@@ -21,7 +21,9 @@ func (c *Context) SendMail(rw web.ResponseWriter, req *web.Request) {
 
 	// Read request body
 	body, err := io.ReadAll(req.Body)
-	req.Body.Close()
+	if closeErr := req.Body.Close(); closeErr != nil {
+		c.printError(closeErr)
+	}
 	if err != nil {
 		c.printError(err)
 		rw.WriteHeader(http.StatusBadRequest)
@@ -54,5 +56,7 @@ func (c *Context) SendMail(rw web.ResponseWriter, req *web.Request) {
 
 	// Return the sent email
 	rw.WriteHeader(http.StatusOK)
-	rw.Write(data)
+	if _, err := rw.Write(data); err != nil {
+		c.printError(err)
+	}
 }

web/router.go

@@ -36,7 +36,9 @@ func setMailServiceProvider(mailServiceProvider func() gotify.MailService) func(
 	return func(c *Context, rw web.ResponseWriter, req *web.Request, next web.NextMiddlewareFunc) {
 		c.MailService = mailServiceProvider()
 		next(rw, req)
-		c.MailService.Destroy()
+		if err := c.MailService.Destroy(); err != nil {
+			c.printError(err)
+		}
 	}
 }
 

web/router_test.go

@@ -28,7 +28,7 @@ func TestRoutingContract(t *testing.T) {
 			req.Header.Set("Authorization", "pre-shared: secret")
 			response, err := server.Client().Do(req)
 			require.NoError(t, err)
-			defer response.Body.Close()
+			defer func() { assert.NoError(t, response.Body.Close()) }()
 			assert.Equal(t, tc.status, response.StatusCode)
 		})
 	}