refactor: use strings.Builder for string accumulation (#513)

Replace repeated string concatenation with `strings.Builder` to reduce allocations and improve performance.

Signed-off-by: Ryan Johnson <ryan@tenthirtyam.org>

Author: tenthirtyam

builder/vmware/common/driver.go

@@ -352,7 +352,7 @@ func NewDriver(dconfig *DriverConfig, config *SSHConfig, vmName string) (Driver,
 		return nil, fmt.Errorf("error finding a driver for %s", runtime.GOOS)
 	}
 
-	errs := ""
+	var errs strings.Builder
 	for _, driver := range drivers {
 		err := driver.Verify()
 
@@ -362,10 +362,10 @@ func NewDriver(dconfig *DriverConfig, config *SSHConfig, vmName string) (Driver,
 		}
 
 		log.Printf("[INFO] Skipping %T because it failed with the following error %s", driver, err)
-		errs += "* " + err.Error() + "\n"
+		errs.WriteString("* " + err.Error() + "\n")
 	}
 
-	return nil, fmt.Errorf("driver initialization failed. fix at least one driver to continue:\n%s", errs)
+	return nil, fmt.Errorf("driver initialization failed. fix at least one driver to continue:\n%s", errs.String())
 }
 
 // runAndLog executes the given command, logs its execution, and returns its stdout, stderr, and any encountered error.

builder/vmware/common/driver_parser_test.go

@@ -36,11 +36,11 @@ func uncommentFromString(s string) string {
 	inCh := consumeString(s)
 	out := uncomment(inCh)
 
-	result := ""
+	var result strings.Builder
 	for item := range out {
-		result += string(item)
+		result.WriteString(string(item))
 	}
-	return result
+	return result.String()
 }
 
 func TestParserUncomment(t *testing.T) {
@@ -492,11 +492,11 @@ func TestParserReadNetworkMap(t *testing.T) {
 }
 
 func collectIntoString(in chan byte) string {
-	result := ""
+	var result strings.Builder
 	for item := range in {
-		result += string(item)
+		result.WriteString(string(item))
 	}
-	return result
+	return result.String()
 }
 
 func TestParserConsumeUntilSentinel(t *testing.T) {