perf(config/env): use strings.LastIndexByte instead of strings.LastIndex (#3660)

* perf(config/env): use strings.LastIndexByte instead of strings.LastIndex

* test(config/env): add test cases for TestFormat

* test(config/file): add benchmark test for format function

---------

Co-authored-by: huangzw <[email protected]>
Co-authored-by: 1911860538 <[email protected]>

Author: 3 people

config/file/format.go

@@ -3,7 +3,7 @@ package file
 import "strings"
 
 func format(name string) string {
-	if idx := strings.LastIndex(name, "."); idx >= 0 {
+	if idx := strings.LastIndexByte(name, '.'); idx >= 0 {
 		return name[idx+1:]
 	}
 	return ""

config/file/format_test.go

@@ -21,6 +21,10 @@ func TestFormat(t *testing.T) {
 			input:  ".",
 			expect: "",
 		},
+		{
+			input:  "a",
+			expect: "",
+		},
 		{
 			input:  "a.",
 			expect: "",
@@ -33,6 +37,10 @@ func TestFormat(t *testing.T) {
 			input:  "a.b",
 			expect: "b",
 		},
+		{
+			input:  "a.b.c",
+			expect: "c",
+		},
 	}
 	for _, v := range tests {
 		content := format(v.input)
@@ -41,3 +49,9 @@ func TestFormat(t *testing.T) {
 		}
 	}
 }
+
+func BenchmarkFormat(b *testing.B) {
+	for i := 0; i < b.N; i++ {
+		format("abc.txt")
+	}
+}