Tests: fail informatively instead of panicking the whole package

internal/handler/api_test.go

@@ -53,6 +53,59 @@ func authReq(method, path, body, apiKey string) *http.Request {
 	return r
 }
 
+// ---------------------------------------------------------------------------
+// Response helpers
+//
+// Reading a body before checking the status hides the one thing that explains a
+// failure, and `id := body["id"].(string)` on a body that has no id PANICS — which
+// aborts the whole package, so a single bad request reports a nil-interface stack
+// trace and no other handler test result at all.
+//
+// That is not hypothetical: a webhook create returning
+// `400 webhook URL must not resolve to a private or loopback address` presented as an
+// unrelated-looking panic, with the status and message nowhere on screen.
+//
+// These four keep a failure local and self-explaining. Each takes a `what` naming the
+// call, so a test that makes several requests still says which one failed.
+// ---------------------------------------------------------------------------
+
+// mustStatus fails the test unless rec carries the wanted status, quoting the body.
+func mustStatus(t *testing.T, rec *httptest.ResponseRecorder, want int, what string) {
+	t.Helper()
+	if rec.Code != want {
+		t.Fatalf("%s: status = %d; want %d — %s", what, rec.Code, want, rec.Body.String())
+	}
+}
+
+// mustJSON asserts the status first, then decodes the JSON body into a map.
+func mustJSON(t *testing.T, rec *httptest.ResponseRecorder, want int, what string) map[string]any {
+	t.Helper()
+	mustStatus(t, rec, want, what)
+	var body map[string]any
+	if err := json.Unmarshal(rec.Body.Bytes(), &body); err != nil {
+		t.Fatalf("%s: decode body: %v — %s", what, err, rec.Body.String())
+	}
+	return body
+}
+
+// mustCreated is mustJSON for 201, which is what most of these calls return.
+func mustCreated(t *testing.T, rec *httptest.ResponseRecorder, what string) map[string]any {
+	t.Helper()
+	return mustJSON(t, rec, http.StatusCreated, what)
+}
+
+// mustString reads a string field, failing with the whole body when it is missing or of
+// another type. The two-value assertion alone yields "" and defers the failure to
+// something downstream — a 404 on an empty id — that cannot explain itself.
+func mustString(t *testing.T, body map[string]any, key, what string) string {
+	t.Helper()
+	v, ok := body[key].(string)
+	if !ok {
+		t.Fatalf("%s: response has no string %q — %v", what, key, body)
+	}
+	return v
+}
+
 // seedEventType creates an event type via the HTTP handler.
 func seedEventTypeHTTP(t *testing.T, h *handler.Handler, apiKey string) (slug, id string) {
 	t.Helper()
@@ -426,13 +479,9 @@ func TestCreateAndListAvailabilityRule(t *testing.T) {
 	req := authReq(http.MethodPost, "/v1/availability-rules", body, key)
 	rec := httptest.NewRecorder()
 	h.RequireAuth(h.CreateAvailabilityRule)(rec, req)
-	if rec.Code != http.StatusCreated {
-		t.Fatalf("create rule: %d — %s", rec.Code, rec.Body.String())
-	}
 
-	var created map[string]any
-	json.Unmarshal(rec.Body.Bytes(), &created)
-	ruleID, _ := created["id"].(string)
+	created := mustCreated(t, rec, "create rule")
+	ruleID := mustString(t, created, "id", "create rule")
 	if ruleID == "" {
 		t.Fatal("rule id is empty")
 	}
@@ -652,12 +701,8 @@ func TestGetBooking_public(t *testing.T) {
 	req.Header.Set("Content-Type", "application/json")
 	rec := httptest.NewRecorder()
 	h.CreateBooking(rec, req)
-	if rec.Code != http.StatusCreated {
-		t.Fatalf("create: %d", rec.Code)
-	}
-	var created map[string]any
-	json.Unmarshal(rec.Body.Bytes(), &created)
-	bookingID := created["id"].(string)
+	created := mustCreated(t, rec, "create booking")
+	bookingID := mustString(t, created, "id", "create booking")
 
 	// Get without auth key.
 	req2 := httptest.NewRequest(http.MethodGet, "/v1/bookings/"+bookingID, nil)
@@ -685,12 +730,8 @@ func TestCancelBooking(t *testing.T) {
 	req.Header.Set("Content-Type", "application/json")
 	rec := httptest.NewRecorder()
 	h.CreateBooking(rec, req)
-	if rec.Code != http.StatusCreated {
-		t.Fatalf("create: %d", rec.Code)
-	}
-	var created map[string]any
-	json.Unmarshal(rec.Body.Bytes(), &created)
-	bookingID := created["id"].(string)
+	created := mustCreated(t, rec, "create booking")
+	bookingID := mustString(t, created, "id", "create booking")
 
 	// Cancel.
 	cancelReq := authReq(http.MethodPost, "/v1/bookings/"+bookingID+"/cancel",

internal/handler/availability_rule_test.go

@@ -36,7 +36,7 @@ func TestUpdateAvailabilityRule_updateTimes(t *testing.T) {
 	if code != http.StatusCreated {
 		t.Fatalf("create rule: %d — %v", code, created)
 	}
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create rule")
 
 	req := authReq(http.MethodPatch, "/v1/availability-rules/"+id,
 		`{"start_time":"10:00","end_time":"18:00"}`, key)
@@ -64,7 +64,7 @@ func TestUpdateAvailabilityRule_updateDayOfWeek(t *testing.T) {
 	if code != http.StatusCreated {
 		t.Fatalf("create rule: %d — %v", code, created)
 	}
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create rule")
 
 	req := authReq(http.MethodPatch, "/v1/availability-rules/"+id,
 		`{"day_of_week":2}`, key)
@@ -103,7 +103,7 @@ func TestUpdateAvailabilityRule_invalidDayOfWeek(t *testing.T) {
 	if code != http.StatusCreated {
 		t.Fatalf("create rule: %d — %v", code, created)
 	}
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create rule")
 
 	req := authReq(http.MethodPatch, "/v1/availability-rules/"+id,
 		`{"day_of_week":7}`, key)
@@ -123,7 +123,7 @@ func TestUpdateAvailabilityRule_invalidHHMM(t *testing.T) {
 	if code != http.StatusCreated {
 		t.Fatalf("create rule: %d — %v", code, created)
 	}
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create rule")
 
 	req := authReq(http.MethodPatch, "/v1/availability-rules/"+id,
 		`{"start_time":"9:00"}`, key)
@@ -143,7 +143,7 @@ func TestUpdateAvailabilityRule_endNotAfterStart(t *testing.T) {
 	if code != http.StatusCreated {
 		t.Fatalf("create rule: %d — %v", code, created)
 	}
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create rule")
 
 	req := authReq(http.MethodPatch, "/v1/availability-rules/"+id,
 		`{"start_time":"17:00","end_time":"09:00"}`, key)
@@ -176,7 +176,7 @@ func TestUpdateAvailabilityRule_conflictWith409(t *testing.T) {
 	if code2 != http.StatusCreated {
 		t.Fatalf("create rule 2: %d — %v", code2, created2)
 	}
-	id2, _ := created2["id"].(string)
+	id2 := mustString(t, created2, "id", "create second rule")
 
 	// Patch rule 2 to have the same day_of_week as rule 1 → conflict.
 	req := authReq(http.MethodPatch, "/v1/availability-rules/"+id2,

internal/handler/invites_test.go

@@ -96,9 +96,8 @@ func TestGetInvite_valid(t *testing.T) {
 
 	rec := httptest.NewRecorder()
 	h.RequireAuth(h.CreateInvite)(rec, createInviteReq("bob@example.com", key))
-	var created map[string]any
-	json.Unmarshal(rec.Body.Bytes(), &created)
-	inviteURL := created["invite_url"].(string)
+	created := mustCreated(t, rec, "create invite")
+	inviteURL := mustString(t, created, "invite_url", "create invite")
 	// Extract token from URL (last path segment).
 	parts := strings.Split(inviteURL, "/")
 	token := parts[len(parts)-1]
@@ -137,9 +136,8 @@ func TestClaimInvite_success(t *testing.T) {
 	// Create invite.
 	rec := httptest.NewRecorder()
 	h.RequireAuth(h.CreateInvite)(rec, createInviteReq("bob@example.com", key))
-	var created map[string]any
-	json.Unmarshal(rec.Body.Bytes(), &created)
-	parts := strings.Split(created["invite_url"].(string), "/")
+	created := mustCreated(t, rec, "create invite")
+	parts := strings.Split(mustString(t, created, "invite_url", "create invite"), "/")
 	token := parts[len(parts)-1]
 
 	// Claim it.
@@ -170,9 +168,8 @@ func TestClaimInvite_cannotReuseToken(t *testing.T) {
 
 	rec := httptest.NewRecorder()
 	h.RequireAuth(h.CreateInvite)(rec, createInviteReq("bob@example.com", key))
-	var created map[string]any
-	json.Unmarshal(rec.Body.Bytes(), &created)
-	parts := strings.Split(created["invite_url"].(string), "/")
+	created := mustCreated(t, rec, "create invite")
+	parts := strings.Split(mustString(t, created, "invite_url", "create invite"), "/")
 	token := parts[len(parts)-1]
 
 	claimBody := `{"name":"Bob","password":"bobspassword1","timezone":"UTC"}`
@@ -219,9 +216,8 @@ func TestRevokeInvite_success(t *testing.T) {
 
 	rec := httptest.NewRecorder()
 	h.RequireAuth(h.CreateInvite)(rec, createInviteReq("bob@example.com", key))
-	var created map[string]any
-	json.Unmarshal(rec.Body.Bytes(), &created)
-	inviteID := created["id"].(string)
+	created := mustCreated(t, rec, "create invite")
+	inviteID := mustString(t, created, "id", "create invite")
 
 	req := authReq(http.MethodDelete, "/v1/invites/"+inviteID, "", key)
 	req.SetPathValue("id", inviteID)
@@ -253,10 +249,9 @@ func TestResendInvite_reissuesFreshLink(t *testing.T) {
 
 	rec := httptest.NewRecorder()
 	h.RequireAuth(h.CreateInvite)(rec, createInviteReq("bob@example.com", key))
-	var created map[string]any
-	json.Unmarshal(rec.Body.Bytes(), &created)
-	origID := created["id"].(string)
-	origURL := created["invite_url"].(string)
+	created := mustCreated(t, rec, "create invite")
+	origID := mustString(t, created, "id", "create invite")
+	origURL := mustString(t, created, "invite_url", "create invite")
 
 	req := authReq(http.MethodPost, "/v1/invites/"+origID+"/resend", "", key)
 	req.SetPathValue("id", origID)

internal/handler/mcp_oauth_test.go

@@ -133,8 +133,8 @@ func TestMCP_OAuthFlow(t *testing.T) {
 	if rec.Code != http.StatusOK {
 		t.Fatalf("token: %d — %s", rec.Code, rec.Body.String())
 	}
-	access, _ := body["access_token"].(string)
-	refresh, _ := body["refresh_token"].(string)
+	access := mustString(t, body, "access_token", "token exchange")
+	refresh := mustString(t, body, "refresh_token", "token exchange")
 	if access == "" || refresh == "" {
 		t.Fatalf("token: missing tokens: %v", body)
 	}
@@ -154,7 +154,7 @@ func TestMCP_OAuthFlow(t *testing.T) {
 	if rec.Code != http.StatusOK {
 		t.Fatalf("refresh: %d — %s", rec.Code, rec.Body.String())
 	}
-	newAccess, _ := body["access_token"].(string)
+	newAccess := mustString(t, body, "access_token", "refresh grant")
 	if newAccess == "" || newAccess == access {
 		t.Fatalf("refresh: expected a new access token, got %q", newAccess)
 	}

internal/handler/override_test.go

@@ -221,7 +221,7 @@ func TestDeleteAvailabilityOverride_success(t *testing.T) {
 	h, key, _ := setupWorkspace(t)
 
 	_, created := createOverride(t, h, key, `{"date":"2026-07-04","is_available":false}`)
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create override")
 	if id == "" {
 		t.Fatal("created id is empty")
 	}
@@ -266,7 +266,7 @@ func TestDeleteAvailabilityOverride_cannotDeleteOtherUsersOverride(t *testing.T)
 	h, keyA, _ := setupWorkspace(t)
 
 	_, created := createOverride(t, h, keyA, `{"date":"2026-07-04","is_available":false}`)
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create override")
 
 	// A second handler instance (same in-memory DB used via h) won't help here;
 	// in practice userB would be a different user. But since we only have one user
@@ -411,7 +411,7 @@ func TestUpdateAvailabilityOverride_updateTimes(t *testing.T) {
 
 	_, created := createOverride(t, h, key,
 		`{"date":"2026-08-01","is_available":true,"start_time":"10:00","end_time":"14:00"}`)
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create override")
 	if id == "" {
 		t.Fatal("created id is empty")
 	}
@@ -443,7 +443,7 @@ func TestUpdateAvailabilityOverride_flipToBlocked(t *testing.T) {
 
 	_, created := createOverride(t, h, key,
 		`{"date":"2026-08-02","is_available":true,"start_time":"09:00","end_time":"17:00"}`)
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create override")
 	if id == "" {
 		t.Fatal("created id is empty")
 	}
@@ -475,7 +475,7 @@ func TestUpdateAvailabilityOverride_flipToAvailable(t *testing.T) {
 
 	_, created := createOverride(t, h, key,
 		`{"date":"2026-08-03","is_available":false}`)
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create override")
 	if id == "" {
 		t.Fatal("created id is empty")
 	}
@@ -521,7 +521,7 @@ func TestUpdateAvailabilityOverride_missingTimesWhenAvailable(t *testing.T) {
 
 	_, created := createOverride(t, h, key,
 		`{"date":"2026-08-04","is_available":false}`)
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create override")
 	if id == "" {
 		t.Fatal("created id is empty")
 	}
@@ -542,7 +542,7 @@ func TestUpdateAvailabilityOverride_startNotBeforeEnd(t *testing.T) {
 
 	_, created := createOverride(t, h, key,
 		`{"date":"2026-08-05","is_available":true,"start_time":"09:00","end_time":"17:00"}`)
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create override")
 	if id == "" {
 		t.Fatal("created id is empty")
 	}
@@ -563,7 +563,7 @@ func TestUpdateAvailabilityOverride_invalidHHMM(t *testing.T) {
 
 	_, created := createOverride(t, h, key,
 		`{"date":"2026-08-06","is_available":true,"start_time":"09:00","end_time":"17:00"}`)
-	id, _ := created["id"].(string)
+	id := mustString(t, created, "id", "create override")
 	if id == "" {
 		t.Fatal("created id is empty")
 	}

internal/handler/webhook_test.go

@@ -32,7 +32,7 @@ func TestCreateWebhook_success(t *testing.T) {
 	if resp["id"] == "" {
 		t.Error("expected non-empty id")
 	}
-	secret, _ := resp["secret"].(string)
+	secret := mustString(t, resp, "secret", "create webhook")
 	if len(secret) != 64 {
 		t.Errorf("secret length = %d; want 64 hex chars", len(secret))
 	}
@@ -208,12 +208,8 @@ func TestDeleteWebhook_success(t *testing.T) {
 		`{"url":"https://example.com/hook","events":["booking.created"]}`, apiKey)
 	createRec := httptest.NewRecorder()
 	h.RequireAuth(h.CreateWebhook)(createRec, createReq)
-	if createRec.Code != http.StatusCreated {
-		t.Fatalf("create: %d", createRec.Code)
-	}
-	var created map[string]any
-	json.Unmarshal(createRec.Body.Bytes(), &created)
-	id := created["id"].(string)
+	created := mustCreated(t, createRec, "create webhook")
+	id := mustString(t, created, "id", "create webhook")
 
 	// Delete.
 	delReq := authReq(http.MethodDelete, "/v1/webhooks/"+id, "", apiKey)
@@ -263,9 +259,8 @@ func TestListWebhookDeliveries_emptyInitially(t *testing.T) {
 		`{"url":"https://example.com/hook","events":["booking.created"]}`, apiKey)
 	createRec := httptest.NewRecorder()
 	h.RequireAuth(h.CreateWebhook)(createRec, createReq)
-	var created map[string]any
-	json.Unmarshal(createRec.Body.Bytes(), &created)
-	id := created["id"].(string)
+	created := mustCreated(t, createRec, "create webhook")
+	id := mustString(t, created, "id", "create webhook")
 
 	req := authReq(http.MethodGet, "/v1/webhooks/"+id+"/deliveries", "", apiKey)
 	req.SetPathValue("id", id)