chore: delint ioutil usage (#962)

This also bumps the minimum supported version of Go to 1.16 (which itself has beel EOL for almost 3 years now)

Co-authored-by: Vojtech Vitek (golang.cz) <[email protected]>

Author: costela

middleware/compress.go

@@ -7,7 +7,6 @@ import (
 	"errors"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"strings"
@@ -160,16 +159,14 @@ func (c *Compressor) SetEncoder(encoding string, fn EncoderFunc) {
 	delete(c.encoders, encoding)
 
 	// If the encoder supports Resetting (IoReseterWriter), then it can be pooled.
-	encoder := fn(ioutil.Discard, c.level)
-	if encoder != nil {
-		if _, ok := encoder.(ioResetterWriter); ok {
-			pool := &sync.Pool{
-				New: func() interface{} {
-					return fn(ioutil.Discard, c.level)
-				},
-			}
-			c.pooledEncoders[encoding] = pool
+	encoder := fn(io.Discard, c.level)
+	if _, ok := encoder.(ioResetterWriter); ok {
+		pool := &sync.Pool{
+			New: func() interface{} {
+				return fn(io.Discard, c.level)
+			},
 		}
+		c.pooledEncoders[encoding] = pool
 	}
 	// If the encoder is not in the pooledEncoders, add it to the normal encoders.
 	if _, ok := c.pooledEncoders[encoding]; !ok {

middleware/middleware_test.go

@@ -3,7 +3,6 @@ package middleware
 import (
 	"crypto/tls"
 	"io"
-	"io/ioutil"
 	"net/http"
 	"net/http/httptest"
 	"path"
@@ -93,7 +92,7 @@ func testRequest(t *testing.T, ts *httptest.Server, method, path string, body io
 		return nil, ""
 	}
 
-	respBody, err := ioutil.ReadAll(resp.Body)
+	respBody, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Fatal(err)
 		return nil, ""
@@ -123,7 +122,7 @@ func testRequestNoRedirect(t *testing.T, ts *httptest.Server, method, path strin
 		return nil, ""
 	}
 
-	respBody, err := ioutil.ReadAll(resp.Body)
+	respBody, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Fatal(err)
 		return nil, ""

middleware/wrap_writer.go

@@ -6,7 +6,6 @@ package middleware
 import (
 	"bufio"
 	"io"
-	"io/ioutil"
 	"net"
 	"net/http"
 )
@@ -108,7 +107,7 @@ func (b *basicWriter) Write(buf []byte) (n int, err error) {
 	} else if b.tee != nil {
 		n, err = b.tee.Write(buf)
 	} else {
-		n, err = ioutil.Discard.Write(buf)
+		n, err = io.Discard.Write(buf)
 	}
 	b.bytes += n
 	return n, err

mux_test.go

@@ -5,7 +5,6 @@ import (
 	"context"
 	"fmt"
 	"io"
-	"io/ioutil"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -186,7 +185,7 @@ func TestMuxBasic(t *testing.T) {
 		t.Fatal(err)
 	}
 
-	body, err := ioutil.ReadAll(resp.Body)
+	body, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -1368,7 +1367,7 @@ func TestServeHTTPExistingContext(t *testing.T) {
 		}
 		req = req.WithContext(tc.Ctx)
 		r.ServeHTTP(resp, req)
-		b, err := ioutil.ReadAll(resp.Body)
+		b, err := io.ReadAll(resp.Body)
 		if err != nil {
 			t.Fatalf("%v", err)
 		}
@@ -1965,7 +1964,7 @@ func testRequest(t *testing.T, ts *httptest.Server, method, path string, body io
 		return nil, ""
 	}
 
-	respBody, err := ioutil.ReadAll(resp.Body)
+	respBody, err := io.ReadAll(resp.Body)
 	if err != nil {
 		t.Fatal(err)
 		return nil, ""