diff --git a/carddav/carddav_test.go b/carddav/carddav_test.go
new file mode 100644
index 0000000..0377a9f
--- /dev/null
+++ b/carddav/carddav_test.go
@@ -0,0 +1,174 @@
+package carddav
+
+import (
+	"context"
+	"fmt"
+	"net/http"
+	"net/http/httptest"
+	"strings"
+	"testing"
+
+	"github.com/emersion/go-vcard"
+	"github.com/emersion/go-webdav"
+)
+
+type testBackend struct{}
+
+type contextKey string
+
+var (
+	aliceData = `BEGIN:VCARD
+VERSION:4.0
+UID:urn:uuid:4fbe8971-0bc3-424c-9c26-36c3e1eff6b1
+FN;PID=1.1:Alice Gopher
+N:Gopher;Alice;;;
+EMAIL;PID=1.1:alice@example.com
+CLIENTPIDMAP:1;urn:uuid:53e374d9-337e-4727-8803-a1e9c14e0551
+END:VCARD`
+	alicePath = "urn:uuid:4fbe8971-0bc3-424c-9c26-36c3e1eff6b1.vcf"
+
+	currentUserPrincipalKey = "test:currentUserPrincipal"
+	homeSetPathKey          = "test:homeSetPath"
+	addressBookPathKey      = "test:addressBookPath"
+)
+
+func (*testBackend) CurrentUserPrincipal(ctx context.Context) (string, error) {
+	r := ctx.Value(currentUserPrincipalKey).(string)
+	return r, nil
+}
+
+func (*testBackend) AddressbookHomeSetPath(ctx context.Context) (string, error) {
+	r := ctx.Value(homeSetPathKey).(string)
+	return r, nil
+}
+
+func (*testBackend) AddressBook(ctx context.Context) (*AddressBook, error) {
+	p := ctx.Value(addressBookPathKey).(string)
+	return &AddressBook{
+		Path:                 p,
+		Name:                 "My contacts",
+		Description:          "Default address book",
+		MaxResourceSize:      1024,
+		SupportedAddressData: nil,
+	}, nil
+}
+
+func (*testBackend) GetAddressObject(ctx context.Context, path string, req *AddressDataRequest) (*AddressObject, error) {
+	if path == alicePath {
+		card, err := vcard.NewDecoder(strings.NewReader(aliceData)).Decode()
+		if err != nil {
+			return nil, err
+		}
+		return &AddressObject{
+			Path: path,
+			Card: card,
+		}, nil
+	} else {
+		return nil, webdav.NewHTTPError(404, fmt.Errorf("Not found"))
+	}
+}
+
+func (b *testBackend) ListAddressObjects(ctx context.Context, req *AddressDataRequest) ([]AddressObject, error) {
+	alice, err := b.GetAddressObject(ctx, alicePath, req)
+	if err != nil {
+		return nil, err
+	}
+
+	return []AddressObject{*alice}, nil
+}
+
+func (*testBackend) QueryAddressObjects(ctx context.Context, query *AddressBookQuery) ([]AddressObject, error) {
+	panic("TODO: implement")
+}
+
+func (*testBackend) PutAddressObject(ctx context.Context, path string, card vcard.Card, opts *PutAddressObjectOptions) (loc string, err error) {
+	panic("TODO: implement")
+}
+
+func (*testBackend) DeleteAddressObject(ctx context.Context, path string) error {
+	panic("TODO: implement")
+}
+
+func TestAddressBookDiscovery(t *testing.T) {
+	for _, tc := range []struct {
+		name                 string
+		currentUserPrincipal string
+		homeSetPath          string
+		addressBookPath      string
+	}{
+		// TODO this used to work, but is currently broken.
+		//{
+		//	name:  "all-at-root",
+		//	currentUserPrincipal: "/",
+		//	homeSetPath: "/",
+		//	addressBookPath: "/",
+		//},
+		{
+			name:                 "simple-home-set-path",
+			currentUserPrincipal: "/",
+			homeSetPath:          "/contacts/",
+			addressBookPath:      "/contacts/",
+		},
+		{
+			name:                 "all-at-different-paths",
+			currentUserPrincipal: "/",
+			homeSetPath:          "/contacts/",
+			addressBookPath:      "/contacts/work",
+		},
+		{
+			name:                 "nothing-at-root",
+			currentUserPrincipal: "/test/",
+			homeSetPath:          "/test/contacts/",
+			addressBookPath:      "/test/contacts/private",
+		},
+	} {
+		t.Run(tc.name, func(t *testing.T) {
+
+			h := Handler{&testBackend{}}
+			ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+				ctx := r.Context()
+				ctx = context.WithValue(ctx, currentUserPrincipalKey, tc.currentUserPrincipal)
+				ctx = context.WithValue(ctx, homeSetPathKey, tc.homeSetPath)
+				ctx = context.WithValue(ctx, addressBookPathKey, tc.addressBookPath)
+				r = r.WithContext(ctx)
+				(&h).ServeHTTP(w, r)
+			}))
+			defer ts.Close()
+
+			// client supports .well-known discovery if explicitly pointed to it
+			startURL := ts.URL
+			if tc.currentUserPrincipal != "/" {
+				startURL = ts.URL + "/.well-known/carddav"
+			}
+
+			client, err := NewClient(nil, startURL)
+			if err != nil {
+				t.Fatalf("error creating client: %s", err)
+			}
+			cup, err := client.FindCurrentUserPrincipal()
+			if err != nil {
+				t.Fatalf("error finding user principal url: %s", err)
+			}
+			if cup != tc.currentUserPrincipal {
+				t.Fatalf("Found current user principal URL '%s', expected '%s'", cup, tc.currentUserPrincipal)
+			}
+			hsp, err := client.FindAddressBookHomeSet(cup)
+			if err != nil {
+				t.Fatalf("error finding home set path: %s", err)
+			}
+			if hsp != tc.homeSetPath {
+				t.Fatalf("Found home set path '%s', expected '%s'", hsp, tc.homeSetPath)
+			}
+			abs, err := client.FindAddressBooks(hsp)
+			if err != nil {
+				t.Fatalf("error finding address books: %s", err)
+			}
+			if len(abs) != 1 {
+				t.Fatalf("Found %d address books, expected 1", len(abs))
+			}
+			if abs[0].Path != tc.addressBookPath {
+				t.Fatalf("Found address book at %s, expected %s", abs[0].Path, tc.addressBookPath)
+			}
+		})
+	}
+}