fix(netfault): report repeated tc batch errors only once

go/action_kit_commons/network/netfault/batch_error.go

@@ -48,10 +48,23 @@ func (t *batchError) Error() string {
 }
 
 func (t *batchErrors) Error() string {
+	occurrences := make(map[string]int)
+	for _, err := range t.Errors {
+		occurrences[err.Msg]++
+	}
+
 	var sb strings.Builder
 	sb.WriteString(fmt.Sprintf("Command failed %s\n", strings.Join(t.Cmd, " ")))
+	reported := make(map[string]bool)
 	for _, err := range t.Errors {
+		if reported[err.Msg] {
+			continue
+		}
+		reported[err.Msg] = true
 		sb.WriteString(err.Error())
+		if count := occurrences[err.Msg]; count > 1 {
+			sb.WriteString(fmt.Sprintf(" (and %d more)", count-1))
+		}
 		sb.WriteString("\n")
 	}
 	return sb.String()

go/action_kit_commons/network/netfault/batch_error_test.go

@@ -31,6 +31,23 @@ Command failed -:2
 Error: Parent Qdisc doesn't exists.
 We have an error talking to the kernel
 Command failed -:3
+`
+	exampleErrorRepeated := `Error: NLM_F_REPLACE needed to override.
+Command failed -:1
+Error: Failed to find specified qdisc.
+Command failed -:2
+Error: Parent Qdisc doesn't exists.
+We have an error talking to the kernel
+Command failed -:3
+Error: Parent Qdisc doesn't exists.
+We have an error talking to the kernel
+Command failed -:4
+Error: Parent Qdisc doesn't exists.
+We have an error talking to the kernel
+Command failed -:5
+Error: Parent Qdisc doesn't exists.
+We have an error talking to the kernel
+Command failed -:6
 `
 
 	tests := []struct {
@@ -56,12 +73,35 @@ Command failed -:3
 			},
 			assert: func(t assert.TestingT, err error, message string) {
 				assert.Equal(t, 3, len(err.(*batchErrors).Errors))
-				assert.Equal(t, exampleError, strings.TrimPrefix(err.Error(), "Command failed test -b -\n"))
+				assert.Equal(t, `Error: Exclusivity flag on, cannot modify.
+Command failed -:1 (and 1 more)
+RTNETLINK answers: File exists
+Command failed -:2
+`, strings.TrimPrefix(err.Error(), "Command failed test -b -\n"))
 				assert.Equal(t, "Error: Exclusivity flag on, cannot modify.", err.(*batchErrors).Errors[0].Msg)
 				assert.Equal(t, "RTNETLINK answers: File exists", err.(*batchErrors).Errors[1].Msg)
 				assert.Equal(t, "Error: Exclusivity flag on, cannot modify.", err.(*batchErrors).Errors[2].Msg)
 			},
 		},
+		{
+			name: "should report repeated errors only once",
+			args: args{
+				cmd: []string{"tc", "-force", "-batch", "-"},
+				r:   strings.NewReader(exampleErrorRepeated),
+			},
+			assert: func(t assert.TestingT, err error, message string) {
+				assert.Equal(t, 6, len(err.(*batchErrors).Errors))
+				assert.Equal(t, `Command failed tc -force -batch -
+Error: NLM_F_REPLACE needed to override.
+Command failed -:1
+Error: Failed to find specified qdisc.
+Command failed -:2
+Error: Parent Qdisc doesn't exists.
+We have an error talking to the kernel
+Command failed -:3 (and 3 more)
+`, err.Error())
+			},
+		},
 		{
 			name: "should add kernel module hint",
 			args: args{