apply v4 jmx fix

Author: cristianciutea

jmx/jmx.go

@@ -275,15 +275,15 @@ func handleStdErr(ctx context.Context) {
 		if strings.HasPrefix(line, "WARNING") {
 			msg := line[7:]
 			if strings.Contains(msg, "Can't parse bean name") {
-				cmdErrC <- ErrBeanPattern
+				cmdErrC <- fmt.Errorf("%w: %s", ErrBeanPattern, msg)
 				return
 			}
 			cmdWarnC <- msg
 		}
 		if strings.HasPrefix(line, "SEVERE:") {
 			msg := line[7:]
 			if strings.Contains(msg, "jmx connection error") {
-				cmdErrC <- ErrConnection
+				cmdErrC <- fmt.Errorf("%w: %s", ErrConnection, msg)
 			} else {
 				cmdErrC <- errors.New(msg)
 			}
@@ -360,7 +360,7 @@ func receiveResult(lineC chan []byte, queryErrC chan error, cancelFn context.Can
 			}
 			var r map[string]interface{}
 			if err = json.Unmarshal(line, &r); err != nil {
-				err = fmt.Errorf("invalid return value for query: %s, error: %s, line: %s", objectPattern, err, line)
+				err = fmt.Errorf("invalid return value for query: %s, error: %w, line: %q", objectPattern, err, line)
 				return
 			}
 			if result == nil {

jmx/jmx_test.go

@@ -4,7 +4,6 @@ import (
 	"bufio"
 	"bytes"
 	"context"
-	"errors"
 	"flag"
 	"fmt"
 	"os"
@@ -225,7 +224,7 @@ func Test_receiveResult_invalidJsonIsPrintedInError(t *testing.T) {
 
 	result, err := receiveResult(resultCh, queryErrCh, cancelFn, "foo", outTimeout)
 
-	assert.Equal(t, err, errors.New("invalid return value for query: foo, error: invalid character '#' looking for beginning of value, line: #this is an invalid json"))
+	assert.Equal(t, "invalid return value for query: foo, error: invalid character '#' looking for beginning of value, line: \"#this is an invalid json\"", err.Error())
 	assert.Nil(t, result)
 }