feat: avoid safe options to be serialized into the measurement (#859)

Skip options that begin with the `Safe` prefix from appearing in the
serialization of a Measurement that will be submitted to the OONI
backend.

Fixes https://github.com/ooni/probe/issues/2214

internal/oonirun/experiment.go

@@ -8,6 +8,7 @@ import (
 	"context"
 	"fmt"
 	"math/rand"
+	"strings"
 	"time"
 
 	"github.com/ooni/probe-cli/v3/internal/engine"
@@ -183,9 +184,16 @@ func (ed *Experiment) newInputLoader(inputPolicy model.InputPolicy) inputLoader
 }
 
 // experimentOptionsToStringList convers the options to []string, which is
-// the format with which we include them into a OONI Measurement
+// the format with which we include them into a OONI Measurement. The resulting
+// []string will skip any option that is named with a `Safe` prefix (case
+// sensitive).
 func experimentOptionsToStringList(options map[string]any) (out []string) {
+	// the prefix to skip inclusion in the string list
+	safeOptionPrefix := "Safe"
 	for key, value := range options {
+		if strings.HasPrefix(key, safeOptionPrefix) {
+			continue
+		}
 		out = append(out, fmt.Sprintf("%s=%v", key, value))
 	}
 	return

internal/oonirun/experiment_test.go

@@ -3,6 +3,8 @@ package oonirun
 import (
 	"context"
 	"os"
+	"reflect"
+	"sort"
 	"testing"
 	"time"
 
@@ -58,3 +60,45 @@ func TestExperimentRunWithExample(t *testing.T) {
 		t.Fatal(err)
 	}
 }
+
+func Test_experimentOptionsToStringList(t *testing.T) {
+	type args struct {
+		options map[string]any
+	}
+	tests := []struct {
+		name    string
+		args    args
+		wantOut []string
+	}{
+		{
+			name: "happy path: a map with three entries returns three items",
+			args: args{
+				map[string]any{
+					"foo":  1,
+					"bar":  2,
+					"baaz": 3,
+				},
+			},
+			wantOut: []string{"baaz=3", "bar=2", "foo=1"},
+		},
+		{
+			name: "an option beginning with `Safe` is skipped from the output",
+			args: args{
+				map[string]any{
+					"foo":     1,
+					"Safefoo": 42,
+				},
+			},
+			wantOut: []string{"foo=1"},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			gotOut := experimentOptionsToStringList(tt.args.options)
+			sort.Strings(gotOut)
+			if !reflect.DeepEqual(gotOut, tt.wantOut) {
+				t.Errorf("experimentOptionsToStringList() = %v, want %v", gotOut, tt.wantOut)
+			}
+		})
+	}
+}

internal/oonirun/v2.go

@@ -46,7 +46,10 @@ type v2Nettest struct {
 	// Inputs contains inputs for the experiment.
 	Inputs []string `json:"inputs"`
 
-	// Options contains the experiment options.
+	// Options contains the experiment options. Any option name starting with
+	// `Safe` will be available for the experiment run, but omitted from
+	// the serialized Measurement that the experiment builder will submit
+	// to the OONI backend.
 	Options map[string]any `json:"options"`
 
 	// TestName contains the nettest name.