crud tests for subjects, assignments and tasks

__tests__/subject/createSubject.test.tsx

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+import { supabase } from "@/lib/supabase";
+import { fireEvent, render, waitFor } from "@testing-library/react-native";
+import { router } from "expo-router";
+import CreateSubject from "../../app/subject/createSubject";
+
+const mockInsert = jest.fn();
+
+jest.mock("expo-router", () => ({
+  router: {
+    back: jest.fn(),
+    replace: jest.fn(),
+  },
+  Stack: {
+    Screen: () => null,
+  },
+}));
+
+jest.mock("@/lib/supabase", () => {
+  return {
+    supabase: {
+      auth: {
+        getUser: jest.fn(() =>
+          Promise.resolve({
+            data: { user: { id: "user-123" } },
+            error: null,
+          })
+        ),
+      },
+      from: jest.fn(() => ({
+        insert: mockInsert,
+      })),
+    },
+  };
+});
+
+test("creates a subject and navigates back", async () => {
+  mockInsert.mockResolvedValue({ error: null });
+
+  const screen = render(<CreateSubject />);
+  fireEvent.changeText(screen.getByTestId("subject-title-input"), "ikt205g26v");
+  fireEvent.press(screen.getByTestId("create-subject-button"));
+
+  await waitFor(() => {
+    expect(supabase.from).toHaveBeenCalledWith("subjects");
+    expect(mockInsert).toHaveBeenCalled();
+    expect(router.back).toHaveBeenCalled();
+  });
+});