refactor(slice): simplify SliceValidationError Error method

[1911860538]

Enhance code readability by replacing the original "switch statement and if conditionals" with a simple "for loop" to iterate over the error slice.

Below is my local test code:

default_validator.go

type SliceValidationError []error

// Error concatenates all error elements in SliceValidationError into a single string separated by \n.
func (err SliceValidationError) Error() string {
	n := len(err)
	switch n {
	case 0:
		return ""
	default:
		var b strings.Builder
		if err[0] != nil {
			fmt.Fprintf(&b, "[%d]: %s", 0, err[0].Error())
		}
		if n > 1 {
			for i := 1; i < n; i++ {
				if err[i] != nil {
					b.WriteString("\n")
					fmt.Fprintf(&b, "[%d]: %s", i, err[i].Error())
				}
			}
		}
		return b.String()
	}
}

func (err SliceValidationError) NewError() string {
	if len(err) == 0 {
		return ""
	}

	var b strings.Builder
	for i := 0; i < len(err); i++ {
		if err[i] != nil {
			if b.Len() > 0 {
				b.WriteString("\n")
			}
			b.WriteString("[" + strconv.Itoa(i) + "]: " + err[i].Error())
		}
	}
	return b.String()
}

default_validator_benchmark_test.go

package binding

import (
	"errors"
	"strconv"
	"testing"

	"github.com/stretchr/testify/assert"
)

func getSliceValidationError(n int) SliceValidationError {
	e := make(SliceValidationError, n)
	for i := 0; i < n; i++ {
		e[i] = errors.New(strconv.Itoa(i))
	}
	return e
}

func TestSameError(t *testing.T) {
	e0 := getSliceValidationError(0)
	assert.Equal(t, e0.Error(), e0.NewError())

	e1 := getSliceValidationError(1)
	assert.Equal(t, e1.Error(), e1.NewError())

	e10 := getSliceValidationError(10)
	assert.Equal(t, e10.Error(), e10.NewError())
}

func BenchmarkSliceValidationError0(b *testing.B) {
	e := getSliceValidationError(0)

	b.ReportAllocs()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		_ = e.Error()
	}
}

func BenchmarkSliceValidationNewError0(b *testing.B) {
	e := getSliceValidationError(0)

	b.ReportAllocs()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		_ = e.NewError()
	}
}

func BenchmarkSliceValidationError1(b *testing.B) {
	e := getSliceValidationError(1)

	b.ReportAllocs()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		_ = e.Error()
	}
}

func BenchmarkSliceValidationNewError1(b *testing.B) {
	e := getSliceValidationError(1)

	b.ReportAllocs()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		_ = e.NewError()
	}
}

func BenchmarkSliceValidationError10(b *testing.B) {
	e := getSliceValidationError(10)

	b.ReportAllocs()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		_ = e.Error()
	}
}

func BenchmarkSliceValidationNewError10(b *testing.B) {
	e := getSliceValidationError(10)

	b.ReportAllocs()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		_ = e.NewError()
	}
}

test output

=== RUN   TestSameError
--- PASS: TestSameError (0.00s)
PASS

Process finished with the exit code 0

benchmark output

goos: darwin
goarch: amd64
pkg: github.com/gin-gonic/gin/binding
cpu: Intel(R) Core(TM) i7-8569U CPU @ 2.80GHz
BenchmarkSliceValidationError0
BenchmarkSliceValidationError0-8       	611569416	         1.911 ns/op	       0 B/op	       0 allocs/op
BenchmarkSliceValidationNewError0
BenchmarkSliceValidationNewError0-8    	614464096	         1.909 ns/op	       0 B/op	       0 allocs/op
BenchmarkSliceValidationError1
BenchmarkSliceValidationError1-8       	 5836453	       196.6 ns/op	      56 B/op	       3 allocs/op
BenchmarkSliceValidationNewError1
BenchmarkSliceValidationNewError1-8    	21680595	        51.82 ns/op	       8 B/op	       1 allocs/op
BenchmarkSliceValidationError10
BenchmarkSliceValidationError10-8      	  705206	      1609 ns/op	     440 B/op	      16 allocs/op
BenchmarkSliceValidationNewError10
BenchmarkSliceValidationNewError10-8   	 2226651	       530.6 ns/op	     248 B/op	       5 allocs/op
PASS

Process finished with the exit code 0

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.18%. Comparing base (3dc1cd6) to head (345707e).
Report is 55 commits behind head on master.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3910      +/-   ##
==========================================
- Coverage   99.21%   99.18%   -0.03%     
==========================================
  Files          42       43       +1     
  Lines        3182     2704     -478     
==========================================
- Hits         3157     2682     -475     
+ Misses         17       12       -5     
- Partials        8       10       +2     

Flag	Coverage Δ
	?
-tags "sonic avx"	99.17% <100.00%> (?)
-tags go_json	99.17% <100.00%> (?)
-tags nomsgpack	99.17% <100.00%> (?)
go-1.18	99.11% <100.00%> (-0.01%)	⬇️
go-1.19	99.18% <100.00%> (-0.03%)	⬇️
go-1.20	99.18% <100.00%> (-0.03%)	⬇️
go-1.21	99.18% <100.00%> (-0.03%)	⬇️
go-1.22	99.18% <100.00%> (?)
macos-latest	99.18% <100.00%> (-0.03%)	⬇️
ubuntu-latest	99.18% <100.00%> (-0.03%)	⬇️

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