Add mirror linter

This flags unnecessary conversions of byte->string and vice versa

Signed-off-by: Anders Eknert <anders@eknert.com>

.golangci.yaml

@@ -11,6 +11,7 @@ linter-settings:
 linters:
   disable-all: true
   enable:
+    - mirror
     - errcheck
     - govet
     - ineffassign

cmd/exec_test.go

@@ -1191,7 +1191,7 @@ func TestExecWithInvalidInputOptions(t *testing.T) {
 					if err != nil {
 						t.Fatalf("unexpected error creating temp file: %q", err.Error())
 					}
-					if _, err := tempFile.Write([]byte(tt.input)); err != nil {
+					if _, err := tempFile.WriteString(tt.input); err != nil {
 						t.Fatalf("unexpeced error when writing to temp file: %q", err.Error())
 					}
 					if _, err := tempFile.Seek(0, 0); err != nil {

cmd/internal/exec/exec_test.go

@@ -209,7 +209,7 @@ func TestExec(t *testing.T) {
 					if err != nil {
 						t.Fatalf("unexpected error creating temp file: %q", err.Error())
 					}
-					if _, err := tempFile.Write([]byte(tt.input)); err != nil {
+					if _, err := tempFile.WriteString(tt.input); err != nil {
 						t.Fatalf("unexpeced error when writing to temp file: %q", err.Error())
 					}
 					if _, err := tempFile.Seek(0, 0); err != nil {

compile/compile_test.go

@@ -1893,7 +1893,7 @@ func modulesToString(modules []bundle.ModuleFile) string {
 	for i, m := range modules {
 		buf.WriteString(strconv.Itoa(i))
 		buf.WriteString(":\n")
-		buf.WriteString(string(m.Raw))
+		buf.Write(m.Raw)
 		buf.WriteString("\n\n")
 	}
 	return buf.String()

topdown/http.go

@@ -473,7 +473,7 @@ func createHTTPRequest(bctx BuiltinContext, obj ast.Object) (*http.Request, *htt
 			}
 			body = bytes.NewBuffer(bodyValBytes)
 		case "raw_body":
-			rawBody = bytes.NewBuffer([]byte(strVal))
+			rawBody = bytes.NewBufferString(strVal)
 		case "tls_use_system_certs":
 			tempTLSUseSystemCerts, err := strconv.ParseBool(obj.Get(val).String())
 			if err != nil {