refactor: continue to simplify engine/netx (#769)

The objective of this diff is to simplify the code inside engine/netx
while moving more bits of code inside netxlite.

See https://github.com/ooni/probe/issues/2121

internal/netxlite/bogon_test.go

@@ -1,6 +1,140 @@
 package netxlite
 
-import "testing"
+import (
+	"context"
+	"errors"
+	"testing"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/ooni/probe-cli/v3/internal/model/mocks"
+)
+
+func TestBogonResolver(t *testing.T) {
+	t.Run("LookupHost", func(t *testing.T) {
+		t.Run("with failure", func(t *testing.T) {
+			expected := errors.New("mocked")
+			reso := &BogonResolver{
+				Resolver: &mocks.Resolver{
+					MockLookupHost: func(ctx context.Context, domain string) ([]string, error) {
+						return nil, expected
+					},
+				},
+			}
+			ctx := context.Background()
+			addrs, err := reso.LookupHost(ctx, "dns.google")
+			if !errors.Is(err, expected) {
+				t.Fatal("unexpected err", err)
+			}
+			if len(addrs) > 0 {
+				t.Fatal("expected no addrs")
+			}
+		})
+
+		t.Run("with success and no bogon", func(t *testing.T) {
+			expected := []string{"8.8.8.8", "149.112.112.112"}
+			reso := &BogonResolver{
+				Resolver: &mocks.Resolver{
+					MockLookupHost: func(ctx context.Context, domain string) ([]string, error) {
+						return expected, nil
+					},
+				},
+			}
+			ctx := context.Background()
+			addrs, err := reso.LookupHost(ctx, "dns.google")
+			if err != nil {
+				t.Fatal(err)
+			}
+			if diff := cmp.Diff(expected, addrs); diff != "" {
+				t.Fatal(diff)
+			}
+		})
+
+		t.Run("with success and bogon", func(t *testing.T) {
+			reso := &BogonResolver{
+				Resolver: &mocks.Resolver{
+					MockLookupHost: func(ctx context.Context, domain string) ([]string, error) {
+						return []string{"8.8.8.8", "10.34.34.35", "149.112.112.112"}, nil
+					},
+				},
+			}
+			ctx := context.Background()
+			addrs, err := reso.LookupHost(ctx, "dns.google")
+			if !errors.Is(err, ErrDNSBogon) {
+				t.Fatal("unexpected err", err)
+			}
+			if len(addrs) > 0 {
+				t.Fatal("expected no addrs")
+			}
+		})
+	})
+
+	t.Run("LookupHTTPS", func(t *testing.T) {
+		ctx := context.Background()
+		reso := &BogonResolver{}
+		https, err := reso.LookupHTTPS(ctx, "dns.google")
+		if !errors.Is(err, ErrNoDNSTransport) {
+			t.Fatal("unexpected err", err)
+		}
+		if https != nil {
+			t.Fatal("expected nil https here")
+		}
+	})
+
+	t.Run("LookupNS", func(t *testing.T) {
+		ctx := context.Background()
+		reso := &BogonResolver{}
+		ns, err := reso.LookupNS(ctx, "dns.google")
+		if !errors.Is(err, ErrNoDNSTransport) {
+			t.Fatal("unexpected err", err)
+		}
+		if len(ns) > 0 {
+			t.Fatal("expected empty ns here")
+		}
+	})
+
+	t.Run("Network", func(t *testing.T) {
+		expected := "antani"
+		reso := &BogonResolver{
+			Resolver: &mocks.Resolver{
+				MockNetwork: func() string {
+					return expected
+				},
+			},
+		}
+		if reso.Network() != expected {
+			t.Fatal("unexpected network")
+		}
+	})
+
+	t.Run("Address", func(t *testing.T) {
+		expected := "antani"
+		reso := &BogonResolver{
+			Resolver: &mocks.Resolver{
+				MockAddress: func() string {
+					return expected
+				},
+			},
+		}
+		if reso.Address() != expected {
+			t.Fatal("unexpected address")
+		}
+	})
+
+	t.Run("CloseIdleConnections", func(t *testing.T) {
+		var called bool
+		reso := &BogonResolver{
+			Resolver: &mocks.Resolver{
+				MockCloseIdleConnections: func() {
+					called = true
+				},
+			},
+		}
+		reso.CloseIdleConnections()
+		if !called {
+			t.Fatal("not called")
+		}
+	})
+}
 
 func TestIsBogon(t *testing.T) {
 	if IsBogon("antani") != true {