fix some errCheck warnings, and update examples

- Explicitly suppress some unhandled errors
- Use "pass" credentials helper in examples, which is available
  on more platforms than "secretservice" (only supporte on Linux)
- Update domain and username in examples.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

client/client_test.go

@@ -92,16 +92,16 @@ func mockProgramFn(args ...string) Program {
 }
 
 func ExampleStore() {
-	p := NewShellProgramFunc("docker-credential-secretservice")
+	p := NewShellProgramFunc("docker-credential-pass")
 
 	c := &credentials.Credentials{
-		ServerURL: "https://example.com",
-		Username:  "calavera",
+		ServerURL: "https://registry.example.com",
+		Username:  "exampleuser",
 		Secret:    "my super secret token",
 	}
 
 	if err := Store(p, c); err != nil {
-		fmt.Println(err)
+		_, _ = fmt.Println(err)
 	}
 }
 
@@ -129,14 +129,14 @@ func TestStore(t *testing.T) {
 }
 
 func ExampleGet() {
-	p := NewShellProgramFunc("docker-credential-secretservice")
+	p := NewShellProgramFunc("docker-credential-pass")
 
-	creds, err := Get(p, "https://example.com")
+	creds, err := Get(p, "https://registry.example.com")
 	if err != nil {
-		fmt.Println(err)
+		_, _ = fmt.Println(err)
 	}
 
-	fmt.Printf("Got credentials for user `%s` in `%s`\n", creds.Username, creds.ServerURL)
+	_, _ = fmt.Printf("Got credentials for user `%s` in `%s`\n", creds.Username, creds.ServerURL)
 }
 
 func TestGet(t *testing.T) {
@@ -190,10 +190,10 @@ func TestGet(t *testing.T) {
 }
 
 func ExampleErase() {
-	p := NewShellProgramFunc("docker-credential-secretservice")
+	p := NewShellProgramFunc("docker-credential-pass")
 
-	if err := Erase(p, "https://example.com"); err != nil {
-		fmt.Println(err)
+	if err := Erase(p, "https://registry.example.com"); err != nil {
+		_, _ = fmt.Println(err)
 	}
 }
 

credentials/credentials.go

@@ -59,7 +59,7 @@ func Serve(helper Helper) {
 	}
 
 	if err != nil {
-		fmt.Fprintf(os.Stdout, "%v\n", err)
+		_, _ = fmt.Fprintln(os.Stdout, err)
 		os.Exit(1)
 	}
 }
@@ -143,7 +143,7 @@ func Get(helper Helper, reader io.Reader, writer io.Writer) error {
 		return err
 	}
 
-	fmt.Fprint(writer, buffer.String())
+	_, _ = fmt.Fprint(writer, buffer.String())
 	return nil
 }
 
@@ -181,6 +181,6 @@ func List(helper Helper, writer io.Writer) error {
 
 // PrintVersion outputs the current version.
 func PrintVersion(writer io.Writer) error {
-	fmt.Fprintf(writer, "%s (%s) %s\n", Name, Package, Version)
+	_, _ = fmt.Fprintf(writer, "%s (%s) %s\n", Name, Package, Version)
 	return nil
 }