Add errorlint and fix all existing issues (#1855)

.golangci.yaml

@@ -9,6 +9,7 @@ run:
 linters:
   enable:
     - asciicheck
+    - errorlint
     - golint
     - gosec
     - prealloc

apis/duck/enqueue_test.go

@@ -97,7 +97,7 @@ func TestEnqueueInformerFactoryWithFailure(t *testing.T) {
 		Resource: "caches",
 	}
 	inf, _, got := eif.Get(context.Background(), gvr)
-	if got != want {
+	if !errors.Is(got, want) {
 		t.Fatalf("Get() = %v, wanted %v", got, want)
 	}
 

apis/duck/typed_test.go

@@ -110,7 +110,7 @@ func TestInvalidResource(t *testing.T) {
 
 	_, _, got := tif.Get(context.Background(), SchemeGroupVersion.WithResource("resources"))
 
-	if got != errTest {
+	if !errors.Is(got, errTest) {
 		t.Errorf("Error = %v, want: %v", got, errTest)
 	}
 }
@@ -124,7 +124,7 @@ func TestAsStructuredWatcherNestedError(t *testing.T) {
 	wf := duck.AsStructuredWatcher(context.Background(), nwf, &duckv1alpha1.AddressableType{})
 
 	_, got := wf(metav1.ListOptions{})
-	if got != want {
+	if !errors.Is(got, want) {
 		t.Errorf("WatchFunc() = %v, wanted %v", got, want)
 	}
 }

apis/duck/unstructured_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package duck
 
 import (
+	"errors"
 	"testing"
 
 	"encoding/json"
@@ -83,7 +84,7 @@ func TestFromUnstructuredFooable(t *testing.T) {
 			t.Log("Marshalled:", string(raw))
 
 			got := Foo{}
-			if err := FromUnstructured(tc.in, &got); err != tc.wantError {
+			if err := FromUnstructured(tc.in, &got); !errors.Is(err, tc.wantError) {
 				t.Fatal("FromUnstructured() =", err)
 			}
 
@@ -145,7 +146,7 @@ func TestToUnstructured(t *testing.T) {
 	for _, tc := range tests {
 		t.Run(tc.name, func(t *testing.T) {
 			got, err := ToUnstructured(tc.in)
-			if err != tc.wantError {
+			if !errors.Is(err, tc.wantError) {
 				t.Fatal("ToUnstructured() =", err)
 			}
 

apis/duck/verify.go

@@ -79,17 +79,17 @@ func roundTrip(instance interface{}, input, output Populatable) error {
 	// Serialize the input to JSON and deserialize that into the provided instance
 	// of the type that we are checking.
 	if before, err := json.Marshal(input); err != nil {
-		return fmt.Errorf("error serializing duck type %T error: %s", input, err)
+		return fmt.Errorf("error serializing duck type %T error: %w", input, err)
 	} else if err := json.Unmarshal(before, instance); err != nil {
-		return fmt.Errorf("error deserializing duck type %T into %T error: %s", input, instance, err)
+		return fmt.Errorf("error deserializing duck type %T into %T error: %w", input, instance, err)
 	}
 
 	// Serialize the instance we are checking to JSON and deserialize that into the
 	// output resource.
 	if after, err := json.Marshal(instance); err != nil {
-		return fmt.Errorf("error serializing %T error: %s", instance, err)
+		return fmt.Errorf("error serializing %T error: %w", instance, err)
 	} else if err := json.Unmarshal(after, output); err != nil {
-		return fmt.Errorf("error deserializing %T into duck type %T error: %s", instance, output, err)
+		return fmt.Errorf("error deserializing %T into duck type %T error: %w", instance, output, err)
 	}
 
 	return nil

configmap/store_test.go

@@ -199,7 +199,9 @@ func TestStoreFailedFirstConversionCrashes(t *testing.T) {
 	cmd := exec.Command(os.Args[0], fmt.Sprintf("-test.run=%s", t.Name()))
 	cmd.Env = append(os.Environ(), "CRASH=1")
 	err := cmd.Run()
-	if e, ok := err.(*exec.ExitError); ok && !e.Success() {
+
+	var errExit *exec.ExitError
+	if errors.As(err, &errExit) && !errExit.Success() {
 		return
 	}
 	t.Fatal("process should have exited with status 1 - err", err)

controller/controller.go

@@ -582,6 +582,7 @@ func IsPermanentError(err error) bool {
 // Is implements the Is() interface of error. It returns whether the target
 // error can be treated as equivalent to a permanentError.
 func (permanentError) Is(target error) bool {
+	//nolint: errorlint // This check is actually fine.
 	_, ok := target.(permanentError)
 	return ok
 }

depcheck/depcheck.go

@@ -104,7 +104,7 @@ func buildGraph(importpaths ...string) (graph, error) {
 func CheckNoDependency(ip string, banned []string) error {
 	g, err := buildGraph(ip)
 	if err != nil {
-		return fmt.Errorf("buildGraph(queue) = %v", err)
+		return fmt.Errorf("buildGraph(queue) = %w", err)
 	}
 	for _, dip := range banned {
 		if g.contains(dip) {
@@ -136,7 +136,7 @@ func AssertNoDependency(t *testing.T, banned map[string][]string) {
 func CheckOnlyDependencies(ip string, allowed map[string]struct{}) error {
 	g, err := buildGraph(ip)
 	if err != nil {
-		return fmt.Errorf("buildGraph(queue) = %v", err)
+		return fmt.Errorf("buildGraph(queue) = %w", err)
 	}
 	for _, name := range g.order() {
 		if _, ok := allowed[name]; !ok {

injection/sharedmain/main.go

@@ -18,6 +18,7 @@ package sharedmain
 
 import (
 	"context"
+	"errors"
 	"flag"
 	"log"
 	"net/http"
@@ -241,7 +242,7 @@ func MainWithConfig(ctx context.Context, component string, cfg *rest.Config, cto
 
 	profilingServer.Shutdown(context.Background())
 	// Don't forward ErrServerClosed as that indicates we're already shutting down.
-	if err := eg.Wait(); err != nil && err != http.ErrServerClosed {
+	if err := eg.Wait(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 		logger.Errorw("Error while running server", zap.Error(err))
 	}
 }

kvstore/kvstore_cm.go

@@ -92,7 +92,7 @@ func (cs *configMapKVStore) Get(ctx context.Context, key string, value interface
 	}
 	err := json.Unmarshal([]byte(v), value)
 	if err != nil {
-		return fmt.Errorf("failed to Unmarshal %q: %v", v, err)
+		return fmt.Errorf("failed to Unmarshal %q: %w", v, err)
 	}
 	return nil
 }
@@ -101,7 +101,7 @@ func (cs *configMapKVStore) Get(ctx context.Context, key string, value interface
 func (cs *configMapKVStore) Set(ctx context.Context, key string, value interface{}) error {
 	bytes, err := json.Marshal(value)
 	if err != nil {
-		return fmt.Errorf("failed to Marshal: %v", err)
+		return fmt.Errorf("failed to Marshal: %w", err)
 	}
 	cs.data[key] = string(bytes)
 	return nil

logging/config.go

@@ -212,7 +212,7 @@ func UpdateLevelFromConfigMap(logger *zap.SugaredLogger, atomicLevel zap.AtomicL
 			// reset to global level
 			loggingCfg, err := zapConfigFromJSON(config.LoggingConfig)
 			switch {
-			case err == errEmptyLoggerConfig:
+			case errors.Is(err, errEmptyLoggerConfig):
 				level = zap.NewAtomicLevel().Level()
 			case err != nil:
 				logger.With(zap.Error(err)).Errorf("Failed to parse logger configuration. "+

metrics/opencensus_exporter.go

@@ -85,7 +85,7 @@ func getOpenCensusSecret(component string, lister SecretFetcher) (*corev1.Secret
 		secret, err = lister("opencensus")
 	}
 	if err != nil {
-		return nil, fmt.Errorf("unable to fetch opencensus secret for %q, cannot use requireSecure=true: %+v", component, err)
+		return nil, fmt.Errorf("unable to fetch opencensus secret for %q, cannot use requireSecure=true: %w", component, err)
 	}
 
 	return secret, nil

metrics/resource_view_test.go

@@ -18,6 +18,7 @@ package metrics
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io"
 	"io/ioutil"
@@ -739,7 +740,7 @@ func (oc *openCensusFake) Export(stream ocmetrics.MetricsService_ExportServer) e
 	metricSeen := false
 	for {
 		in, err := stream.Recv()
-		if err == io.EOF {
+		if errors.Is(err, io.EOF) {
 			return nil
 		}
 		if err != nil {

metrics/stackdriver_exporter.go

@@ -363,7 +363,7 @@ func getStackdriverSecret(ctx context.Context, secretFetcher SecretFetcher) (*co
 	}
 
 	if secErr != nil {
-		return nil, fmt.Errorf("error getting Secret [%v] in namespace [%v]: %v", secretName, secretNamespace, secErr)
+		return nil, fmt.Errorf("error getting Secret [%v] in namespace [%v]: %w", secretName, secretNamespace, secErr)
 	}
 
 	return sec, nil

network/prober/prober_test.go

@@ -18,6 +18,7 @@ package prober
 
 import (
 	"context"
+	"errors"
 	"net"
 	"net/http"
 	"net/http/httptest"
@@ -222,7 +223,7 @@ func TestDoAsyncTimeout(t *testing.T) {
 		if done {
 			t.Errorf("done was true")
 		}
-		if err != wait.ErrWaitTimeout {
+		if !errors.Is(err, wait.ErrWaitTimeout) {
 			t.Error("Unexpected error =", err)
 		}
 		wch <- arg

network/transports.go

@@ -18,6 +18,7 @@ package network
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
@@ -76,7 +77,8 @@ func dialBackOffHelper(ctx context.Context, network, address string, bo wait.Bac
 	for {
 		c, err := dialer.DialContext(ctx, network, address)
 		if err != nil {
-			if err, ok := err.(net.Error); ok && err.Timeout() {
+			var errNet net.Error
+			if errors.As(err, &errNet) && errNet.Timeout() {
 				if bo.Steps < 1 {
 					break
 				}

pool/pool_test.go

@@ -163,7 +163,7 @@ func TestParallelismWithErrors(t *testing.T) {
 					time.Sleep(10 * time.Millisecond)
 
 					// Make all unexpected errors wait.
-					if err != errExpected {
+					if !errors.Is(err, errExpected) {
 						<-barrier
 					}
 					return err
@@ -193,7 +193,7 @@ func TestParallelismWithErrors(t *testing.T) {
 			// remaining work.
 			wg.Wait()
 
-			if err := p.Wait(); err != errExpected {
+			if err := p.Wait(); !errors.Is(err, errExpected) {
 				t.Errorf("Wait() = %v, wanted %v", err, errExpected)
 			}
 
@@ -241,7 +241,7 @@ func TestErrorCancelsContext(t *testing.T) {
 	case <-time.After(100 * time.Millisecond):
 		t.Error("ctx is not canceled due to the first error")
 	}
-	if err := pool.Wait(); err != want {
+	if err := pool.Wait(); !errors.Is(err, want) {
 		t.Fatalf("pool.Wait() = %v, want: %v", err, want)
 	}
 }

reconciler/events.go

@@ -75,7 +75,8 @@ var _ error = (*ReconcilerEvent)(nil)
 // Is returns if the target error is a ReconcilerEvent type checking that
 // EventType and Reason match.
 func (e *ReconcilerEvent) Is(target error) bool {
-	if t, ok := target.(*ReconcilerEvent); ok {
+	var t *ReconcilerEvent
+	if errors.As(target, &t) {
 		if t != nil && t.EventType == e.EventType && t.Reason == e.Reason {
 			return true
 		}

reconciler/retry_test.go

@@ -69,7 +69,7 @@ func TestRetryUpdateConflicts(t *testing.T) {
 				return test.returns[i]
 			})
 
-			if got != test.want {
+			if !errors.Is(got, test.want) {
 				t.Errorf("RetryUpdateConflicts() = %v, want %v", got, test.want)
 			}
 			if attempts != test.wantAttempts {
@@ -125,7 +125,7 @@ func TestRetryTestErrors(t *testing.T) {
 				return test.returns[i]
 			})
 
-			if got != test.want {
+			if !errors.Is(got, test.want) {
 				t.Errorf("RetryTestErrors() = %v, want %v", got, test.want)
 			}
 			if attempts != test.wantAttempts {

test/cmd/command.go

@@ -18,6 +18,7 @@ package cmd
 
 import (
 	"bytes"
+	"errors"
 	"os/exec"
 	"strings"
 	"sync"
@@ -143,8 +144,10 @@ func runCommandsInParallel(cmdLines ...string) (string, error) {
 // getErrorCode extracts the exit code of an *ExitError type
 func getErrorCode(err error) int {
 	errorCode := defaultErrCode
-	if exitError, ok := err.(*exec.ExitError); ok {
-		errorCode = exitError.ExitCode()
+
+	var errExit *exec.ExitError
+	if errors.As(err, &errExit) {
+		errorCode = errExit.ExitCode()
 	}
 	return errorCode
 }

test/cmd/command_test.go

@@ -17,6 +17,7 @@ limitations under the License.
 package cmd
 
 import (
+	"errors"
 	"reflect"
 	"testing"
 )
@@ -65,7 +66,8 @@ func TestRunCommand(t *testing.T) {
 			t.Fatalf("Expect %q but actual is %q", c.expectedOutput, out)
 		}
 		if err != nil {
-			if ce, ok := err.(*CommandLineError); ok {
+			var ce *CommandLineError
+			if errors.As(err, &ce) {
 				if ce.ErrorCode != c.expectedErrorCode {
 					t.Fatalf("Expect to get error code %d but got %d", c.expectedErrorCode, ce.ErrorCode)
 				}
@@ -130,7 +132,8 @@ func TestRunCommands(t *testing.T) {
 			t.Fatalf("Expect %q but actual is %q", c.expectedOutput, out)
 		}
 		if err != nil {
-			if ce, ok := err.(*CommandLineError); ok {
+			var ce *CommandLineError
+			if errors.As(err, &ce) {
 				if ce.ErrorCode != c.expectedErrorCode {
 					t.Fatalf("Expect to get error code %d but got %d", c.expectedErrorCode, ce.ErrorCode)
 				}

test/gcs/gcs.go

@@ -136,11 +136,11 @@ func (g *GCSClient) getObjectsAttrs(ctx context.Context, bucketName, storagePath
 
 	for {
 		attrs, err := it.Next()
-		if err == iterator.Done {
+		if errors.Is(err, iterator.Done) {
 			break
 		}
 		if err != nil {
-			return nil, fmt.Errorf("error iterating: %v", err)
+			return nil, fmt.Errorf("error iterating: %w", err)
 		}
 		allAttrs = append(allAttrs, attrs)
 	}

test/gcs/mock/mock_test.go

@@ -19,6 +19,7 @@ package mock
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -379,7 +380,7 @@ func TestNewStorageBucket(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			err := mockClient.NewStorageBucket(ctx, tt.bkt, tt.projectName)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -441,7 +442,7 @@ func TestDeleteStorageBucket(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			err := mockClient.DeleteStorageBucket(ctx, tt.bkt, tt.force)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -568,7 +569,7 @@ func TestListChildrenFiles(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			children, err := mockClient.ListChildrenFiles(ctx, tt.bkt, tt.dir)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -634,7 +635,7 @@ func TestListDirectChildren(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			children, err := mockClient.ListDirectChildren(ctx, tt.bkt, tt.dir)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -690,7 +691,7 @@ func TestAttrObject(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			objAttr, err := mockClient.AttrObject(ctx, tt.bkt, tt.objpath)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -781,7 +782,7 @@ func TestCopyObject(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			err := mockClient.CopyObject(ctx, tt.srcBkt, tt.srcObjPath, tt.dstBkt, tt.dstObjPath)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -843,7 +844,7 @@ func TestReadObject(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			objContent, err := mockClient.ReadObject(ctx, tt.bkt, tt.objpath)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -899,7 +900,7 @@ func TestWriteObject(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			n, err := mockClient.WriteObject(ctx, tt.bkt, tt.objpath, tt.content)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -955,7 +956,7 @@ func TestDeleteObject(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			err := mockClient.DeleteObject(ctx, tt.bkt, tt.objpath)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -1013,7 +1014,7 @@ func TestDownload(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			err := mockClient.Download(ctx, tt.bkt, tt.objPath, file)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
@@ -1076,7 +1077,7 @@ func TestUpload(t *testing.T) {
 	for _, tt := range testCases {
 		t.Run(tt.testname, func(t *testing.T) {
 			err := mockClient.Upload(ctx, tt.bkt, tt.objPath, file)
-			if (tt.err == nil || err == nil) && err != tt.err {
+			if (tt.err == nil || err == nil) && !errors.Is(err, tt.err) {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)
 			} else if (tt.err != nil && err != nil) && tt.err.Error() != err.Error() {
 				t.Fatalf("expected error %v, got error %v", tt.err, err)

test/ghutil/client.go

@@ -20,6 +20,7 @@ package ghutil
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"log"
@@ -119,10 +120,11 @@ func (gc *GithubClient) retry(message string, maxRetries int, call func() (*gith
 		if resp, err = call(); nil == err {
 			return resp, nil
 		}
-		switch err := err.(type) {
-		case *github.RateLimitError:
-			gc.waitForRateReset(&err.Rate)
-		default:
+
+		var errRateLimit *github.RateLimitError
+		if errors.As(err, &errRateLimit) {
+			gc.waitForRateReset(&errRateLimit.Rate)
+		} else {
 			return resp, err
 		}
 		log.Printf("error %s: %v. Will retry.\n", message, err)

test/gke/client.go

@@ -45,7 +45,7 @@ type sdkClient struct {
 func NewSDKClient(opts ...option.ClientOption) (SDKOperations, error) {
 	containerService, err := container.NewService(context.Background(), opts...)
 	if err != nil {
-		return nil, fmt.Errorf("failed to create container service: '%v'", err)
+		return nil, fmt.Errorf("failed to create container service: %w", err)
 	}
 	return &sdkClient{containerService}, nil
 }
@@ -110,7 +110,7 @@ func (gsc *sdkClient) ListClustersInProject(project string) ([]*container.Cluste
 	projectFullPath := fmt.Sprintf("projects/%s/locations/-", project)
 	resp, err := gsc.Projects.Locations.Clusters.List(projectFullPath).Do()
 	if err != nil {
-		return clusters, fmt.Errorf("failed to list clusters under project %s: %v", project, err)
+		return clusters, fmt.Errorf("failed to list clusters under project %s: %w", project, err)
 	}
 	return resp.Clusters, nil
 }

test/interactive/docker.go

@@ -47,7 +47,7 @@ func (e Env) PromoteFromEnv(envVars ...string) error {
 	for _, env := range envVars {
 		v := os.Getenv(env)
 		if v == "" {
-			err = fmt.Errorf("environment variable %q is not set; %v", env, err)
+			err = fmt.Errorf("environment variable %q is not set; %w", env, err)
 		} else {
 			e[env] = v
 		}

test/logging/logging_test.go

@@ -122,7 +122,7 @@ func TestTLoggerInternals(legacy *testing.T) {
 	for _, tt := range tests {
 		t.Run("errorWithRuntimeCheck "+tt.testName, func(t *TLogger) {
 			e, s, i := t.errorWithRuntimeCheck(tt.inputs...)
-			if e != tt.expectedError {
+			if !errors.Is(e, tt.expectedError) {
 				t.Error("error did not match", "got", e, "want", tt.expectedError)
 			}
 			if s != tt.expectedString {

test/mako/config/benchmark.go

@@ -51,6 +51,7 @@ func getBenchmark() (*mpb.BenchmarkInfo, error) {
 	if koerr != nil {
 		data, err = ioutil.ReadFile(filepath.Join(configMako, env+".config"))
 		if err != nil {
+			//nolint: errorlint // It's fine not to wrap here.
 			return nil, fmt.Errorf("cannot load both from kodata and from config mako config map: %s, %s", koerr.Error(), err.Error())
 		}
 	}

test/mako/stub-sidecar/main.go

@@ -19,6 +19,7 @@ package main
 import (
 	"context"
 	"encoding/csv"
+	"errors"
 	"flag"
 	"fmt"
 	"net/http"
@@ -158,7 +159,7 @@ func main() {
 		m.HandleFunc("/close", func(writer http.ResponseWriter, request *http.Request) {
 			s.Shutdown(context.Background())
 		})
-		if err := s.ListenAndServe(); err != nil && err != http.ErrServerClosed {
+		if err := s.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
 			log.Fatal(err)
 		}
 		fmt.Println("Successfully served the results")

test/spoof/error_checks.go

@@ -19,13 +19,20 @@ limitations under the License.
 package spoof
 
 import (
+	"errors"
 	"net"
 	"strings"
 )
 
-func isTCPTimeout(e error) bool {
-	err, ok := e.(net.Error)
-	return err != nil && ok && err.Timeout()
+func isTCPTimeout(err error) bool {
+	if err == nil {
+		return false
+	}
+	var errNet net.Error
+	if !errors.As(err, &errNet) {
+		return false
+	}
+	return errNet.Timeout()
 }
 
 func isDNSError(err error) bool {

test/spoof/spoof.go

@@ -237,7 +237,8 @@ func (sc *SpoofingClient) logZipkinTrace(spoofResp *Response) {
 
 	json, err := zipkin.JSONTrace(traceID /* We don't know the expected number of spans */, -1, 5*time.Second)
 	if err != nil {
-		if _, ok := err.(*zipkin.TimeoutError); !ok {
+		var errTimeout *zipkin.TimeoutError
+		if !errors.As(err, &errTimeout) {
 			sc.Logf("Error getting zipkin trace: %v", err)
 		}
 	}

testutils/clustermanager/e2e-tests/common/common.go

@@ -45,7 +45,7 @@ func IsProw() bool {
 func GetRepoName() (string, error) {
 	out, err := StandardExec("git", "rev-parse", "--show-toplevel")
 	if err != nil {
-		return "", fmt.Errorf("failed git rev-parse --show-toplevel: '%v'", err)
+		return "", fmt.Errorf("failed git rev-parse --show-toplevel: %w", err)
 	}
 	return strings.TrimSpace(path.Base(string(out))), nil
 }

testutils/clustermanager/e2e-tests/common/common_test.go

@@ -19,7 +19,6 @@ package common
 import (
 	"errors"
 	"fmt"
-	"reflect"
 	"testing"
 )
 
@@ -68,7 +67,7 @@ func TestGetRepoName(t *testing.T) {
 			"a/b/c/", nil, "c", nil,
 		}, {
 			// Git error
-			"", fmt.Errorf("git error"), "", fmt.Errorf("failed git rev-parse --show-toplevel: 'git error'"),
+			"", fmt.Errorf("git error"), "", fmt.Errorf("failed git rev-parse --show-toplevel: git error"),
 		},
 	}
 
@@ -85,7 +84,7 @@ func TestGetRepoName(t *testing.T) {
 		}
 
 		out, err := GetRepoName()
-		if data.expOut != out || !reflect.DeepEqual(err, data.expErr) {
+		if data.expOut != out || (err != nil && err.Error() != data.expErr.Error()) {
 			t.Errorf("testing getting repo name with:\n\tmocked git output: '%s'\n\tmocked git err: '%v'\nwant: out - '%s', err - '%v'\ngot: out - '%s', err - '%v'",
 				data.out, data.err, data.expOut, data.expErr, out, err)
 		}

testutils/clustermanager/e2e-tests/gke.go

@@ -234,7 +234,7 @@ func (gc *GKECluster) checkEnvironment() error {
 				if (gc.Request.Project == "" || gc.Request.Project == project) && (gc.Request.ClusterName == "" || gc.Request.ClusterName == clusterName) {
 					client, err := gc.newGKEClient(project)
 					if err != nil {
-						return fmt.Errorf("failed creating the GKE client: '%v'", err)
+						return fmt.Errorf("failed creating the GKE client: %w", err)
 					}
 					cluster, err := client.GetCluster(project, region, zone, clusterName)
 					if err != nil {

testutils/clustermanager/e2e-tests/util.go

@@ -44,7 +44,7 @@ func getResourceName(rt ResourceType) (string, error) {
 	var resName string
 	repoName, err := common.GetRepoName()
 	if err != nil {
-		return "", fmt.Errorf("failed getting reponame for forming resource name: '%v'", err)
+		return "", fmt.Errorf("failed getting reponame for forming resource name: %w", err)
 	}
 	resName = fmt.Sprintf("k%s-%s", repoName, string(rt))
 	if common.IsProw() {

testutils/clustermanager/prow-cluster-operation/actions/create.go

@@ -92,7 +92,7 @@ func Create(o *options.RequestWrapper) (*clm.GKECluster, error) {
 	clusterOps := gkeClient.Setup(o.Request)
 	gkeOps := clusterOps.(*clm.GKECluster)
 	if err := gkeOps.Acquire(); err != nil || gkeOps.Cluster == nil {
-		return nil, fmt.Errorf("failed acquiring GKE cluster: '%v'", err)
+		return nil, fmt.Errorf("failed acquiring GKE cluster: %w", err)
 	}
 
 	// At this point we should have a cluster ready to run test. Need to save
@@ -104,10 +104,10 @@ func Create(o *options.RequestWrapper) (*clm.GKECluster, error) {
 	// TODO(chaodaiG): this probably should also be part of clustermanager lib
 	if out, err := common.StandardExec("gcloud", "beta", "container", "clusters", "get-credentials",
 		gkeOps.Cluster.Name, "--region", gkeOps.Cluster.Location, "--project", gkeOps.Project); err != nil {
-		return nil, fmt.Errorf("failed connecting to cluster: %q, '%v'", out, err)
+		return nil, fmt.Errorf("failed connecting to cluster: %q, %w", out, err)
 	}
 	if out, err := common.StandardExec("gcloud", "config", "set", "project", gkeOps.Project); err != nil {
-		return nil, fmt.Errorf("failed setting gcloud: %q, '%v'", out, err)
+		return nil, fmt.Errorf("failed setting gcloud: %q, %w", out, err)
 	}
 
 	return gkeOps, nil

testutils/clustermanager/prow-cluster-operation/actions/delete.go

@@ -33,12 +33,12 @@ func Delete(o *options.RequestWrapper) error {
 	clusterOps := gkeClient.Setup(o.Request)
 	gkeOps := clusterOps.(*clm.GKECluster)
 	if err := gkeOps.Acquire(); err != nil || gkeOps.Cluster == nil {
-		return fmt.Errorf("failed identifying cluster for cleanup: '%v'", err)
+		return fmt.Errorf("failed identifying cluster for cleanup: %w", err)
 	}
 	log.Printf("Identified project %q and cluster %q for removal", gkeOps.Project, gkeOps.Cluster.Name)
 	var err error
 	if err = gkeOps.Delete(); err != nil {
-		return fmt.Errorf("failed deleting cluster: '%v'", err)
+		return fmt.Errorf("failed deleting cluster: %w", err)
 	}
 	// Unset context with best effort. The first command only unsets current
 	// context, but doesn't delete the entry from kubeconfig, and should return it's

tracing/opencensus_test.go

@@ -57,7 +57,7 @@ func TestOpenCensusTraceApplyConfigFailingConfigOption(t *testing.T) {
 		}
 		return nil
 	})
-	if err := oct.ApplyConfig(&config.Config{}); err != coErr {
+	if err := oct.ApplyConfig(&config.Config{}); !errors.Is(err, coErr) {
 		t.Errorf("Expected error not seen. Got %q. Want %q", err, coErr)
 	}
 	if err := oct.Finish(); err != nil {
@@ -81,7 +81,7 @@ func TestOpenCensusTraceFinishFailingConfigOption(t *testing.T) {
 	if err := oct.ApplyConfig(&config.Config{}); err != nil {
 		t.Errorf("Unexpected error Applying Config: %q", err)
 	}
-	if err := oct.Finish(); err != coErr {
+	if err := oct.Finish(); !errors.Is(err, coErr) {
 		t.Errorf("Expected error not seen. Got %q. Want %q", err, coErr)
 	}
 	if err := oct.Finish(); err != nil {

webhook/webhook.go

@@ -209,7 +209,7 @@ func (wh *Webhook) Run(stop <-chan struct{}) error {
 
 	eg, ctx := errgroup.WithContext(ctx)
 	eg.Go(func() error {
-		if err := server.ListenAndServeTLS("", ""); err != nil && err != http.ErrServerClosed {
+		if err := server.ListenAndServeTLS("", ""); err != nil && !errors.Is(err, http.ErrServerClosed) {
 			logger.Errorw("ListenAndServeTLS for admission webhook returned error", zap.Error(err))
 			return err
 		}

websocket/connection_test.go

@@ -138,7 +138,7 @@ func TestSendErrorOnNoConnection(t *testing.T) {
 	conn := &ManagedConnection{}
 	got := conn.Send("test")
 
-	if got != want {
+	if !errors.Is(got, want) {
 		t.Fatalf("Wanted error to be %v, but it was %v.", want, got)
 	}
 }
@@ -149,7 +149,7 @@ func TestStatusOnNoConnection(t *testing.T) {
 	conn := &ManagedConnection{}
 	got := conn.Status()
 
-	if got != want {
+	if !errors.Is(got, want) {
 		t.Fatalf("Wanted error to be %v, but it was %v.", want, got)
 	}
 }
@@ -290,7 +290,7 @@ func TestConnectLoopIsStopped(t *testing.T) {
 
 	select {
 	case err := <-errorChan:
-		if err != errShuttingDown {
+		if !errors.Is(err, errShuttingDown) {
 			t.Errorf("Wrong 'connect' error, got %v, want %v", err, errShuttingDown)
 		}
 	case <-time.After(propagationTimeout):
@@ -316,7 +316,7 @@ func TestKeepaliveLoopIsStopped(t *testing.T) {
 
 	select {
 	case err := <-errorChan:
-		if err != errShuttingDown {
+		if !errors.Is(err, errShuttingDown) {
 			t.Errorf("Wrong 'keepalive' error, got %v, want %v", err, errShuttingDown)
 		}
 	case <-time.After(propagationTimeout):