test: add a lookup test

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mount/lookup_test.go

+package mount
+
+import (
+	"testing"
+
+	datastore "github.com/ipfs/go-datastore"
+)
+
+func TestLookup(t *testing.T) {
+	mapds0 := datastore.NewMapDatastore()
+	mapds1 := datastore.NewMapDatastore()
+	mapds2 := datastore.NewMapDatastore()
+	mapds3 := datastore.NewMapDatastore()
+	m := New([]Mount{
+		{Prefix: datastore.NewKey("/"), Datastore: mapds0},
+		{Prefix: datastore.NewKey("/foo"), Datastore: mapds1},
+		{Prefix: datastore.NewKey("/bar"), Datastore: mapds2},
+		{Prefix: datastore.NewKey("/baz"), Datastore: mapds3},
+	})
+	_, mnts, _ := m.lookupAll(datastore.NewKey("/bar"))
+	if len(mnts) != 1 || mnts[0] != datastore.NewKey("/bar") {
+		t.Errorf("expected to find the mountpoint /bar, got %v", mnts)
+	}
+
+	_, mnts, _ = m.lookupAll(datastore.NewKey("/fo"))
+	if len(mnts) != 1 || mnts[0] != datastore.NewKey("/") {
+		t.Errorf("expected to find the mountpoint /, got %v", mnts)
+	}
+
+	_, mnt, _ := m.lookup(datastore.NewKey("/fo"))
+	if mnt != datastore.NewKey("/") {
+		t.Errorf("expected to find the mountpoint /, got %v", mnt)
+	}
+
+	// /foo lives in /, /foo/bar lives in /foo. Most systems don't let us use the key "" or /.
+	_, mnt, _ = m.lookup(datastore.NewKey("/foo"))
+	if mnt != datastore.NewKey("/") {
+		t.Errorf("expected to find the mountpoint /, got %v", mnt)
+	}
+
+	_, mnt, _ = m.lookup(datastore.NewKey("/foo/bar"))
+	if mnt != datastore.NewKey("/foo") {
+		t.Errorf("expected to find the mountpoint /foo, got %v", mnt)
+	}
+}