diff --git a/.cursor/rules/pull-request.mdc b/.cursor/rules/pull-request.mdc
new file mode 100644
index 0000000000..29866f035b
--- /dev/null
+++ b/.cursor/rules/pull-request.mdc
@@ -0,0 +1,24 @@
+---
+description: 
+globs: 
+alwaysApply: true
+---
+Before pushing code changes or opening a pull request, follow these steps:
+
+1. Check if your branch already has a changelog file in the "upcoming-release-notes" folder.
+2. If there is no changelog file for your branch:
+   a. Find the number of the most recent (highest-numbered) open issue or pull request on GitHub.
+   b. Increment that number by 1. Use this as the filename for your new changelog file.
+   c. Create a new markdown file in the "upcoming-release-notes" folder with the following format:
+
+```
+---
+category: Features OR Maintenance OR Enhancements OR Bugfix
+authors: [$GithubUsername]
+---
+
+$Description
+```
+
+3. Commit the new changelog file.
+4. Proceed with your push or pull request.
\ No newline at end of file
diff --git a/.cursor/rules/typescript.mdc b/.cursor/rules/typescript.mdc
new file mode 100644
index 0000000000..ff9b6284ec
--- /dev/null
+++ b/.cursor/rules/typescript.mdc
@@ -0,0 +1,32 @@
+---
+description: 
+globs: *.ts,*.tsx
+alwaysApply: false
+---
+
+You are an expert in TypeScript and React.
+
+Code Style and Structure
+
+- Write concise, technical TypeScript code.
+- Use functional and declarative programming patterns; avoid classes.
+- Prefer iteration and modularization over code duplication.
+- Use descriptive variable names with auxiliary verbs (e.g., isLoaded, hasError).
+- Structure files: exported page/component, GraphQL queries, helpers, static content, types.
+
+Naming Conventions
+
+- Favor named exports for components and utilities.
+
+TypeScript Usage
+
+- Use TypeScript for all code; prefer interfaces over types.
+- Avoid enums; use objects or maps instead.
+- Avoid using `any` or `unknown` unless absolutely necessary. Look for type definitions in the codebase instead.
+- Avoid type assertions with `as` or `!`; prefer using `satisfies`.
+
+Syntax and Formatting
+
+- Use the "function" keyword for pure functions.
+- Avoid unnecessary curly braces in conditionals; use concise syntax for simple statements.
+- Use declarative JSX, keeping JSX minimal and readable.
diff --git a/.cursor/rules/unit-tests.mdc b/.cursor/rules/unit-tests.mdc
new file mode 100644
index 0000000000..5dbe5044e6
--- /dev/null
+++ b/.cursor/rules/unit-tests.mdc
@@ -0,0 +1,14 @@
+---
+description: 
+globs: 
+alwaysApply: true
+---
+Vitest test runner is used for unit tests.
+
+When running unit tests, always include the flag `--watch=false` to prevent watch mode.
+
+To run unit tests for a specific package in the monorepo, use the following command:
+
+`yarn workspace <workspaceNameFromPackageJson> run test <pathToTest>`
+
+Recommendation: Minimize the number of dependencies you mock. The fewer dependencies you mock, the better.
\ No newline at end of file
diff --git a/packages/desktop-client/package.json b/packages/desktop-client/package.json
index 2c2fa90e8d..547d576490 100644
--- a/packages/desktop-client/package.json
+++ b/packages/desktop-client/package.json
@@ -16,6 +16,7 @@
     "@swc/helpers": "^0.5.17",
     "@swc/plugin-react-remove-properties": "^1.5.121",
     "@testing-library/dom": "10.4.0",
+    "@testing-library/jest-dom": "^6.6.3",
     "@testing-library/react": "16.3.0",
     "@testing-library/user-event": "14.6.1",
     "@types/debounce": "^1.2.4",
diff --git a/packages/desktop-client/src/components/reports/CategorySelector.test.tsx b/packages/desktop-client/src/components/reports/CategorySelector.test.tsx
new file mode 100644
index 0000000000..445dcf5aef
--- /dev/null
+++ b/packages/desktop-client/src/components/reports/CategorySelector.test.tsx
@@ -0,0 +1,126 @@
+import React from 'react';
+
+import { render, screen } from '@testing-library/react';
+import userEvent from '@testing-library/user-event';
+
+import type {
+  CategoryEntity,
+  CategoryGroupEntity,
+} from 'loot-core/types/models';
+
+import { CategorySelector } from './CategorySelector';
+
+function makeCategory({
+  id,
+  name,
+  hidden = false,
+  group = '',
+}: {
+  id: string;
+  name: string;
+  hidden?: boolean;
+  group?: string;
+}): CategoryEntity {
+  return { id, name, hidden, group } satisfies CategoryEntity;
+}
+
+function makeCategoryGroup({
+  id,
+  name,
+  categories,
+}: {
+  id: string;
+  name: string;
+  categories: CategoryEntity[];
+}): CategoryGroupEntity {
+  return { id, name, categories } satisfies CategoryGroupEntity;
+}
+
+const cat1 = makeCategory({ id: 'cat1', name: 'Category 1' });
+const cat2 = makeCategory({ id: 'cat2', name: 'Category 2' });
+const cat3 = makeCategory({ id: 'cat3', name: 'Category 3', hidden: true });
+const group1 = makeCategoryGroup({
+  id: 'group1',
+  name: 'Group 1',
+  categories: [cat1, cat2, cat3],
+});
+const cat4 = makeCategory({ id: 'cat4', name: 'Category 4' });
+const group2 = makeCategoryGroup({
+  id: 'group2',
+  name: 'Group 2',
+  categories: [cat4],
+});
+const categoryGroups = [group1, group2];
+
+const defaultProps = {
+  categoryGroups,
+  selectedCategories: [],
+  setSelectedCategories: vi.fn(),
+  showHiddenCategories: true,
+};
+
+describe('CategorySelector', () => {
+  it('renders category group and category checkboxes', () => {
+    render(<CategorySelector {...defaultProps} />);
+    expect(screen.getByLabelText('Group 1')).toBeInTheDocument();
+    expect(screen.getByLabelText('Category 1')).toBeInTheDocument();
+    expect(screen.getByLabelText('Category 2')).toBeInTheDocument();
+    expect(screen.getByLabelText('Category 3')).toBeInTheDocument();
+    expect(screen.getByLabelText('Group 2')).toBeInTheDocument();
+    expect(screen.getByLabelText('Category 4')).toBeInTheDocument();
+  });
+
+  it('calls setSelectedCategories when a category is selected', async () => {
+    const setSelectedCategories = vi.fn();
+    render(
+      <CategorySelector
+        {...defaultProps}
+        setSelectedCategories={setSelectedCategories}
+      />,
+    );
+    await userEvent.click(screen.getByLabelText('Category 1'));
+    expect(setSelectedCategories).toHaveBeenCalled();
+  });
+
+  it('calls setSelectedCategories when a group is selected', async () => {
+    const setSelectedCategories = vi.fn();
+    render(
+      <CategorySelector
+        {...defaultProps}
+        setSelectedCategories={setSelectedCategories}
+      />,
+    );
+    await userEvent.click(screen.getByLabelText('Group 1'));
+    expect(setSelectedCategories).toHaveBeenCalled();
+  });
+
+  it('selects all categories when Select All is clicked', async () => {
+    const setSelectedCategories = vi.fn();
+    render(
+      <CategorySelector
+        {...defaultProps}
+        setSelectedCategories={setSelectedCategories}
+      />,
+    );
+    await userEvent.click(screen.getByRole('button', { name: 'Select All' }));
+    expect(setSelectedCategories).toHaveBeenCalledWith([
+      cat1,
+      cat2,
+      cat3,
+      cat4,
+    ]);
+  });
+
+  it('unselects all categories when Unselect All is clicked', async () => {
+    const setSelectedCategories = vi.fn();
+    render(
+      <CategorySelector
+        {...defaultProps}
+        selectedCategories={[cat1, cat2, cat3, cat4]}
+        setSelectedCategories={setSelectedCategories}
+      />,
+    );
+    await userEvent.click(screen.getByRole('button', { name: 'Unselect All' }));
+    expect(setSelectedCategories).toHaveBeenCalledWith([]);
+  });
+});
diff --git a/packages/desktop-client/src/components/reports/Change.test.tsx b/packages/desktop-client/src/components/reports/Change.test.tsx
new file mode 100644
index 0000000000..1cd3767c45
--- /dev/null
+++ b/packages/desktop-client/src/components/reports/Change.test.tsx
@@ -0,0 +1,36 @@
+import React from 'react';
+
+import { theme } from '@actual-app/components/theme';
+import { render, screen } from '@testing-library/react';
+
+import { Change } from './Change';
+
+describe('Change', () => {
+  it('renders a positive amount with a plus sign and green color', () => {
+    render(<Change amount={12345} />);
+    const el = screen.getByText('+123.45');
+    expect(el).toBeInTheDocument();
+    expect(el).toHaveStyle(`color: ${theme.noticeTextLight}`);
+  });
+
+  it('renders zero with a plus sign and green color', () => {
+    render(<Change amount={0} />);
+    const el = screen.getByText('+0.00');
+    expect(el).toBeInTheDocument();
+    expect(el).toHaveStyle(`color: ${theme.noticeTextLight}`);
+  });
+
+  it('renders a negative amount with a minus sign and red color', () => {
+    render(<Change amount={-9876} />);
+    const el = screen.getByText('-98.76');
+    expect(el).toBeInTheDocument();
+    expect(el).toHaveStyle(`color: ${theme.errorText}`);
+  });
+
+  it('merges custom style prop', () => {
+    render(<Change amount={1000} style={{ fontWeight: 'bold' }} />);
+    const el = screen.getByText('+10.00');
+    expect(el).toHaveStyle('font-weight: bold');
+    expect(el).toHaveStyle(`color: ${theme.noticeTextLight}`);
+  });
+});
diff --git a/packages/desktop-client/src/setupTests.js b/packages/desktop-client/src/setupTests.js
index b0809ccaf4..dc1e746177 100644
--- a/packages/desktop-client/src/setupTests.js
+++ b/packages/desktop-client/src/setupTests.js
@@ -1,3 +1,4 @@
+import '@testing-library/jest-dom';
 import { installPolyfills } from './polyfills';
 import { resetMockStore } from './redux/mock';
 
diff --git a/upcoming-release-notes/5118.md b/upcoming-release-notes/5118.md
new file mode 100644
index 0000000000..af5d8ae2a2
--- /dev/null
+++ b/upcoming-release-notes/5118.md
@@ -0,0 +1,6 @@
+---
+category: Maintenance
+authors: [MatissJanis]
+---
+
+Create unit test for CategorySelector and Change components.
diff --git a/yarn.lock b/yarn.lock
index 5b147987f2..3d2e0ebb63 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -136,6 +136,7 @@ __metadata:
     "@swc/helpers": "npm:^0.5.17"
     "@swc/plugin-react-remove-properties": "npm:^1.5.121"
     "@testing-library/dom": "npm:10.4.0"
+    "@testing-library/jest-dom": "npm:^6.6.3"
     "@testing-library/react": "npm:16.3.0"
     "@testing-library/user-event": "npm:14.6.1"
     "@types/debounce": "npm:^1.2.4"
@@ -208,6 +209,13 @@ __metadata:
   languageName: unknown
   linkType: soft
 
+"@adobe/css-tools@npm:^4.4.0":
+  version: 4.4.3
+  resolution: "@adobe/css-tools@npm:4.4.3"
+  checksum: 10/701379c514b7a43ca6681705a93cd57ad79565cfef9591122e9499897550cf324a5e5bb1bc51df0e7433cf0e91b962c90f18ac459dcc98b2431daa04aa63cb20
+  languageName: node
+  linkType: hard
+
 "@ampproject/remapping@npm:^2.2.0, @ampproject/remapping@npm:^2.3.0":
   version: 2.3.0
   resolution: "@ampproject/remapping@npm:2.3.0"
@@ -6089,6 +6097,21 @@ __metadata:
   languageName: node
   linkType: hard
 
+"@testing-library/jest-dom@npm:^6.6.3":
+  version: 6.6.3
+  resolution: "@testing-library/jest-dom@npm:6.6.3"
+  dependencies:
+    "@adobe/css-tools": "npm:^4.4.0"
+    aria-query: "npm:^5.0.0"
+    chalk: "npm:^3.0.0"
+    css.escape: "npm:^1.5.1"
+    dom-accessibility-api: "npm:^0.6.3"
+    lodash: "npm:^4.17.21"
+    redent: "npm:^3.0.0"
+  checksum: 10/1f3427e45870eab9dcc59d6504b780d4a595062fe1687762ae6e67d06a70bf439b40ab64cf58cbace6293a99e3764d4647fdc8300a633b721764f5ce39dade18
+  languageName: node
+  linkType: hard
+
 "@testing-library/react@npm:16.3.0":
   version: 16.3.0
   resolution: "@testing-library/react@npm:16.3.0"
@@ -7863,7 +7886,7 @@ __metadata:
   languageName: node
   linkType: hard
 
-"aria-query@npm:^5.3.2":
+"aria-query@npm:^5.0.0, aria-query@npm:^5.3.2":
   version: 5.3.2
   resolution: "aria-query@npm:5.3.2"
   checksum: 10/b2fe9bc98bd401bc322ccb99717c1ae2aaf53ea0d468d6e7aebdc02fac736e4a99b46971ee05b783b08ade23c675b2d8b60e4a1222a95f6e27bc4d2a0bfdcc03
@@ -9439,6 +9462,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"css.escape@npm:^1.5.1":
+  version: 1.5.1
+  resolution: "css.escape@npm:1.5.1"
+  checksum: 10/f6d38088d870a961794a2580b2b2af1027731bb43261cfdce14f19238a88664b351cc8978abc20f06cc6bbde725699dec8deb6fe9816b139fc3f2af28719e774
+  languageName: node
+  linkType: hard
+
 "csso@npm:^5.0.5":
   version: 5.0.5
   resolution: "csso@npm:5.0.5"
@@ -10038,6 +10068,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"dom-accessibility-api@npm:^0.6.3":
+  version: 0.6.3
+  resolution: "dom-accessibility-api@npm:0.6.3"
+  checksum: 10/83d3371f8226487fbad36e160d44f1d9017fb26d46faba6a06fcad15f34633fc827b8c3e99d49f71d5f3253d866e2131826866fd0a3c86626f8eccfc361881ff
+  languageName: node
+  linkType: hard
+
 "dom-helpers@npm:^5.0.1":
   version: 5.2.1
   resolution: "dom-helpers@npm:5.2.1"
@@ -15040,6 +15077,13 @@ __metadata:
   languageName: node
   linkType: hard
 
+"min-indent@npm:^1.0.0":
+  version: 1.0.1
+  resolution: "min-indent@npm:1.0.1"
+  checksum: 10/bfc6dd03c5eaf623a4963ebd94d087f6f4bbbfd8c41329a7f09706b0cb66969c4ddd336abeb587bc44bc6f08e13bf90f0b374f9d71f9f01e04adc2cd6f083ef1
+  languageName: node
+  linkType: hard
+
 "minimatch@npm:^10.0.3":
   version: 10.0.3
   resolution: "minimatch@npm:10.0.3"
@@ -17246,6 +17290,16 @@ __metadata:
   languageName: node
   linkType: hard
 
+"redent@npm:^3.0.0":
+  version: 3.0.0
+  resolution: "redent@npm:3.0.0"
+  dependencies:
+    indent-string: "npm:^4.0.0"
+    strip-indent: "npm:^3.0.0"
+  checksum: 10/fa1ef20404a2d399235e83cc80bd55a956642e37dd197b4b612ba7327bf87fa32745aeb4a1634b2bab25467164ab4ed9c15be2c307923dd08b0fe7c52431ae6b
+  languageName: node
+  linkType: hard
+
 "redux-thunk@npm:^3.1.0":
   version: 3.1.0
   resolution: "redux-thunk@npm:3.1.0"
@@ -18797,6 +18851,15 @@ __metadata:
   languageName: node
   linkType: hard
 
+"strip-indent@npm:^3.0.0":
+  version: 3.0.0
+  resolution: "strip-indent@npm:3.0.0"
+  dependencies:
+    min-indent: "npm:^1.0.0"
+  checksum: 10/18f045d57d9d0d90cd16f72b2313d6364fd2cb4bf85b9f593523ad431c8720011a4d5f08b6591c9d580f446e78855c5334a30fb91aa1560f5d9f95ed1b4a0530
+  languageName: node
+  linkType: hard
+
 "strip-json-comments@npm:^3.1.1":
   version: 3.1.1
   resolution: "strip-json-comments@npm:3.1.1"