1 files changed, 106 insertions, 0 deletions
diff --git a/internal/failover/monitor_test.go b/internal/failover/monitor_test.go
new file mode 100644
index 0000000..87fb3cd
--- /dev/null
+++ b/internal/failover/monitor_test.go
@@ -0,0 +1,106 @@
+package failover
+
+import (
+	"context"
+	"errors"
+	"io"
+	"testing"
+	"time"
+
+	"github.com/eduvpn/eduvpn-common/internal/test"
+)
+
+// mockedPinger is a ping sender that always returns nil for sending
+// but returns EOF for reading
+type mockedPinger struct{}
+
+func (mp *mockedPinger) Read(_ time.Time) error {
+	return io.EOF
+}
+
+func (mp *mockedPinger) Send(_ int) error {
+	return nil
+}
+
+func TestMonitor(t *testing.T) {
+	cases := []struct {
+		interval        time.Duration
+		pDropped        int
+		readRxBytes     func() (int64, error)
+		gateway         string
+		mtuSize         int
+		disableDefaults bool
+		mockedPinger    func(gateway string, mtu int) (sender, error)
+		wantDropped     bool
+		wantErr         string
+	}{
+		{
+			mtuSize:     1,
+			wantDropped: false,
+			wantErr:     "invalid MTU size given, MTU has to be at least: 28 bytes",
+		},
+		{
+			readRxBytes: func() (int64, error) {
+				return 0, errors.New("error test")
+			},
+			wantDropped: false,
+			wantErr:     "error test",
+		},
+		// default case, not dropped
+		{},
+		// readRxBytes always returns 0
+		// still we do not want a drop because we get a pong from 127.0.0.1
+		{
+			readRxBytes: func() (int64, error) {
+				return 0, nil
+			},
+			wantDropped: false,
+		},
+		// readRxBytes always returns 0
+		// we want dropped as the mock pinger does nothing
+		{
+			readRxBytes: func() (int64, error) {
+				return 0, nil
+			},
+			gateway: "127.0.0.1",
+			mockedPinger: func(_ string, _ int) (sender, error) {
+				return &mockedPinger{}, nil
+			},
+			wantDropped: true,
+		},
+	}
+
+	for _, c := range cases {
+		var counter int64
+		// some defaults
+		if c.interval == 0 {
+			c.interval = 2 * time.Second
+		}
+		if c.pDropped == 0 {
+			c.pDropped = 5
+		}
+		if c.gateway == "" {
+			c.gateway = "127.0.0.1"
+		}
+		if c.mtuSize == 0 {
+			c.mtuSize = 28
+		}
+		if c.readRxBytes == nil {
+			c.readRxBytes = func() (int64, error) {
+				defer func() {
+					counter++
+				}()
+				return counter, nil
+			}
+		}
+		dcm := NewDroppedMonitor(c.interval, c.pDropped, c.readRxBytes)
+		if c.mockedPinger != nil {
+			dcm.newPinger = c.mockedPinger
+		}
+		dropped, err := dcm.Start(context.Background(), c.gateway, c.mtuSize)
+		if dropped != c.wantDropped {
+			t.Fatalf("dropped is not equal to want dropped, got: %v, want: %v", dropped, c.wantDropped)
+		}
+		test.AssertError(t, err, c.wantErr)
+	}
+}