diff --git a/backend/tests/models/entry/entry.test.ts b/backend/tests/models/entry/entry.test.ts
new file mode 100644
index 0000000..0bd4909
--- /dev/null
+++ b/backend/tests/models/entry/entry.test.ts
@@ -0,0 +1,181 @@
+/**
+ * @jest-environment node
+ */
+
+import { Entry } from "../../../src/models/index.js";
+
+describe('Entry model tests', () => {
+  let entryObject: any;
+  let expectedResult: any;
+
+  beforeEach(() => {
+    entryObject = {
+      title: 'My Journal',
+      content: 'my content',
+      mood: 'positive',
+      tags: ['test', 'mock', 'jest'],
+      privacy_settings: {
+        public: false,
+        shared_with: ['friend1', 'therapist1']
+      },
+    };
+    expectedResult = {
+      title: 'My Journal',
+      content: 'my content',
+      mood: 'positive',
+      tags: ['test', 'mock', 'jest'],
+      privacy_settings: {
+        public: false,
+        shared_with: ['friend1', 'therapist1']
+      },
+    };
+  });
+
+  it('succeeds on valid input', () => {
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeUndefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('replaces undefined title with Untitled', () => {
+    delete entryObject.title;
+    expectedResult.title = 'Untitled'
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeUndefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('replaces empty title with Untitled', () => {
+    entryObject.title = '';
+    expectedResult.title = 'Untitled';
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeUndefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('returns error if title length over 100 characters', () => {
+    entryObject.title = 'a'.repeat(101);
+    expectedResult.title = 'a'.repeat(101);
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('trims whitespace from title before validating length', () => {
+    entryObject.title = 'a'.repeat(100).padEnd(5, ' ').padStart(5, ' ');
+    expectedResult.title = 'a'.repeat(100);
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeUndefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('returns error if content with less than 4 characters', () => {
+    entryObject.content = '';
+    expectedResult.content = '';
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('returns error if content with more than 1000 characters', () => {
+    entryObject.content = 'a'.repeat(1001);
+    expectedResult.content = 'a'.repeat(1001);
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('does not allow empty strings for mood', () => {
+    entryObject.mood = '';
+    expectedResult.mood = '';
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('requires mood to be a string', () => {
+    entryObject.mood = {};
+    expectedResult.mood = {};
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('requires tags to be array', () => {
+    entryObject.tags = {};
+    expectedResult.tags = {};
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('requires tags elements to be strings', () => {
+    entryObject.tags = [true, false];
+    expectedResult.tags = [true, false];
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('requires privacy_settings to be an object', () => {
+    entryObject.privacy_settings = [];
+    expectedResult.privacy_settings = [];
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('allows privacy_settings to be empty object', () => {
+    entryObject.privacy_settings = {};
+    expectedResult.privacy_settings = {};
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeUndefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('requires privacy_settings.public to be a boolean', () => {
+    entryObject.privacy_settings.public = 1;
+    expectedResult.privacy_settings.public = 1;
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+  it('requires privacy_settings.shared_with to be strings', () => {
+    entryObject.privacy_settings.shared_with = 1;
+    expectedResult.privacy_settings.shared_with = 1;
+
+    const { error, value } = Entry.joi(entryObject, {});
+
+    expect(error).toBeDefined();
+    expect(value).toStrictEqual(expectedResult);
+  });
+
+});
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