Fix linter errors

This commit fixes the linter errors popping up in
#1400
to unblock this PR, to allow rebase other branches
to master without getting stuck on linter errors.

Details of changes
* add missing error-return-check
* remove references to deprecated ioutil package

internal/gcsx/append_object_creator_test.go

@@ -240,7 +240,8 @@ func (t *AppendObjectCreatorTest) CallsComposeObjectsWithObjectProperties() {
 		WillOnce(Return(nil))
 
 	// Call
-	t.call()
+	_, err := t.call()
+	ExpectEq(nil, err)
 
 	AssertNe(nil, req)
 	ExpectEq(t.srcObject.Name, req.DstName)

internal/monitor/exporter.go

@@ -99,10 +99,15 @@ func EnableOpenTelemetryCollectorExporter(address string) error {
 
 // CloseOpenTelemetryCollectorExporter ensures all collected metrics are sent to
 // the OpenTelemetry Collect and closes the exporter.
-func CloseOpenTelemetryCollectorExporter() {
+func CloseOpenTelemetryCollectorExporter() error {
 	if ocExporter != nil {
-		ocExporter.Stop()
+		if err := ocExporter.Stop(); err != nil {
+			return fmt.Errorf("failed to stop opencensus-exporter: %w", err)
+		}
+
 		ocExporter.Flush()
+		ocExporter = nil
 	}
-	ocExporter = nil
+
+	return nil
 }

main.go

@@ -336,13 +336,14 @@ func runCLIApp(c *cli.Context) (err error) {
 
 	// Wait for the file system to be unmounted.
 	err = mfs.Join(context.Background())
+	if err != nil {
+		return fmt.Errorf("failed MountedFileSystem.Join: %w", err)
+	}
 
 	monitor.CloseStackdriverExporter()
-	monitor.CloseOpenTelemetryCollectorExporter()
 
-	if err != nil {
-		err = fmt.Errorf("MountedFileSystem.Join: %w", err)
-		return
+	if err := monitor.CloseOpenTelemetryCollectorExporter(); err != nil {
+		return fmt.Errorf("failed to close open-telemetry collector exporter: %w", err)
 	}
 
 	return

tools/integration_tests/mounting/gcsfuse_linux_test.go

@@ -40,7 +40,9 @@ func (t *GcsfuseTest) Statfs() {
 
 	err = t.runGcsfuse(args)
 	AssertEq(nil, err)
-	defer util.Unmount(t.dir)
+	defer func() {
+		AssertEq(nil, util.Unmount(t.dir))
+	}()
 
 	// Stat the file system.
 	err = syscall.Statfs(t.dir, &stat)

tools/integration_tests/mounting/gcsfuse_test.go

@@ -17,12 +17,10 @@ package integration_test
 import (
 	"bytes"
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path"
 	"path/filepath"
-	//"runtime"
 	"syscall"
 	"testing"
 	"time"
@@ -156,7 +154,7 @@ func (t *GcsfuseTest) NonEmptyMountPoint() {
 
 	// Write a file into the mount point.
 	p := path.Join(t.dir, "foo")
-	err = ioutil.WriteFile(p, nil, 0600)
+	err = os.WriteFile(p, nil, 0600)
 	AssertEq(nil, err)
 
 	defer os.Remove(p)
@@ -175,7 +173,7 @@ func (t *GcsfuseTest) MountPointIsAFile() {
 	// Write a file.
 	p := path.Join(t.dir, "foo")
 
-	err = ioutil.WriteFile(p, []byte{}, 0500)
+	err = os.WriteFile(p, []byte{}, 0500)
 	AssertEq(nil, err)
 	defer os.Remove(p)
 
@@ -216,11 +214,11 @@ func (t *GcsfuseTest) KeyFile() {
 		cmd := t.gcsfuseCommand(args, tc.env)
 
 		output, err := cmd.CombinedOutput()
-		util.Unmount(t.dir)
-
 		ExpectThat(err, Error(HasSubstr("exit status")), "case %d", i)
 		ExpectThat(string(output), HasSubstr(nonexistent), "case %d", i)
 		ExpectThat(string(output), HasSubstr("no such file"), "case %d", i)
+
+		ExpectEq(nil, util.Unmount(t.dir))
 	}
 }
 
@@ -233,14 +231,16 @@ func (t *GcsfuseTest) CannedContents() {
 
 	err = t.runGcsfuse(args)
 	AssertEq(nil, err)
-	defer util.Unmount(t.dir)
+	defer func() {
+		ExpectEq(nil, util.Unmount(t.dir))
+	}()
 
 	// Check the expected contents of the file system.
 	fi, err = os.Lstat(path.Join(t.dir, canned.TopLevelFile))
 	AssertEq(nil, err)
 	ExpectEq(os.FileMode(0644), fi.Mode())
 
-	contents, err := ioutil.ReadFile(path.Join(t.dir, canned.TopLevelFile))
+	contents, err := os.ReadFile(path.Join(t.dir, canned.TopLevelFile))
 	AssertEq(nil, err)
 	ExpectEq(canned.TopLevelFile_Contents, string(contents))
 
@@ -265,7 +265,7 @@ func (t *GcsfuseTest) ReadOnlyMode() {
 	defer util.Unmount(t.dir)
 
 	// Writing to the file system should fail.
-	err = ioutil.WriteFile(path.Join(t.dir, "blah"), []byte{}, 0400)
+	err = os.WriteFile(path.Join(t.dir, "blah"), []byte{}, 0400)
 	ExpectThat(err, Error(HasSubstr("read-only")))
 }
 
@@ -282,10 +282,10 @@ func (t *GcsfuseTest) ReadWriteMode() {
 	// Overwrite the canned file.
 	p := path.Join(t.dir, canned.TopLevelFile)
 
-	err = ioutil.WriteFile(p, []byte("enchilada"), 0400)
+	err = os.WriteFile(p, []byte("enchilada"), 0400)
 	AssertEq(nil, err)
 
-	contents, err := ioutil.ReadFile(p)
+	contents, err := os.ReadFile(p)
 	AssertEq(nil, err)
 	ExpectEq("enchilada", string(contents))
 }
@@ -491,8 +491,12 @@ func (t *GcsfuseTest) ForegroundMode() {
 
 	err = cmd.Start()
 	AssertEq(nil, err)
-	defer cmd.Wait()
-	defer cmd.Process.Kill()
+	defer func() {
+		ExpectEq(nil, cmd.Wait())
+	}()
+	defer func() {
+		ExpectEq(nil, cmd.Process.Kill())
+	}()
 
 	// Accumulate output from stderr until we see a successful mount message,
 	// hackily synchronizing. Yes, this is an O(n^2) loop.

tools/integration_tests/mounting/mount_helper_test.go

@@ -16,7 +16,6 @@ package integration_test
 
 import (
 	"fmt"
-	"io/ioutil"
 	"os"
 	"os/exec"
 	"path"
@@ -66,7 +65,7 @@ func (t *MountHelperTest) SetUp(_ *TestInfo) {
 	}
 
 	// Set up the temporary directory.
-	t.dir, err = ioutil.TempDir("", "mount_helper_test")
+	t.dir, err = os.MkdirTemp("", "mount_helper_test")
 	AssertEq(nil, err)
 }
 
@@ -199,7 +198,7 @@ func (t *MountHelperTest) ReadOnlyMode() {
 	defer util.Unmount(t.dir)
 
 	// Writing to the file system should fail.
-	err = ioutil.WriteFile(path.Join(t.dir, "blah"), []byte{}, 0400)
+	err = os.WriteFile(path.Join(t.dir, "blah"), []byte{}, 0400)
 	ExpectThat(err, Error(HasSubstr("read-only")))
 }
 
@@ -236,7 +235,7 @@ func (t *MountHelperTest) LinuxArgumentOrder() {
 	defer util.Unmount(t.dir)
 
 	// Writing to the file system should fail.
-	err = ioutil.WriteFile(path.Join(t.dir, "blah"), []byte{}, 0400)
+	err = os.WriteFile(path.Join(t.dir, "blah"), []byte{}, 0400)
 	ExpectThat(err, Error(HasSubstr("read-only")))
 }