diff --git a/.github/workflows/serve-install.yml b/.github/workflows/serve-install.yml
index 288c1c8cb..a5e634821 100644
--- a/.github/workflows/serve-install.yml
+++ b/.github/workflows/serve-install.yml
@@ -56,6 +56,11 @@ jobs:
         echo "ionic version"
         npx ionic --version
 
+    - name: Run Jest tests
+      shell: bash -l {0}
+      run: |
+        npx jest
+
 # TODO: figure out how to check that a server started correctly
 #    - name: Try starting it
 #      run: npx run serve
diff --git a/jest.config.json b/jest.config.json
new file mode 100644
index 000000000..78dc839b4
--- /dev/null
+++ b/jest.config.json
@@ -0,0 +1,15 @@
+{
+  "testPathIgnorePatterns": [
+    "/node_modules/",
+    "/platforms/",
+    "/plugins/",
+    "/lib/",
+    "/manual_lib/"
+  ],
+  "transform": {
+    "^.+\\.(ts|tsx|js|jsx)$": "ts-jest"
+  },
+  "moduleNameMapper": {
+    "^react-native$": "react-native-web"
+  }
+}
diff --git a/package.serve.json b/package.serve.json
index da3b60b89..a342a73de 100644
--- a/package.serve.json
+++ b/package.serve.json
@@ -10,7 +10,8 @@
   "scripts": {
     "setup-serve": "./bin/download_settings_controls.js && ./bin/setup_autodeploy.js",
     "serve": "webpack --config webpack.dev.js && concurrently -k \"phonegap --verbose serve\" \"webpack --config webpack.dev.js --watch\"",
-    "serve-only": "phonegap --verbose serve"
+    "serve-only": "phonegap --verbose serve",
+    "test": "npx jest"
   },
   "devDependencies": {
     "@babel/core": "^7.21.3",
@@ -30,11 +31,13 @@
     "exports-loader": "^4.0.0",
     "expose-loader": "^4.1.0",
     "file-loader": "^6.2.0",
+    "jest": "^29.7.0",
     "phonegap": "9.0.0+cordova.9.0.0",
     "process": "^0.11.10",
     "sass": "^1.62.1",
     "sass-loader": "^13.3.1",
     "style-loader": "^3.3.3",
+    "ts-jest": "^29.1.1",
     "ts-loader": "^9.4.2",
     "typescript": "^5.0.3",
     "url-loader": "^4.1.1",
@@ -45,6 +48,7 @@
     "@react-navigation/native": "^6.1.7",
     "@react-navigation/stack": "^6.3.17",
     "@shopify/flash-list": "^1.3.1",
+    "@types/jest": "^29.5.5",
     "angular": "1.6.7",
     "angular-animate": "1.6.7",
     "angular-local-storage": "^0.7.1",
diff --git a/www/__tests__/diaryHelper.test.ts b/www/__tests__/diaryHelper.test.ts
new file mode 100644
index 000000000..429fbd08e
--- /dev/null
+++ b/www/__tests__/diaryHelper.test.ts
@@ -0,0 +1,65 @@
+import { getFormattedSectionProperties, getFormattedDate, motionTypeOf, isMultiDay, getFormattedDateAbbr, getFormattedTimeRange, getPercentages } from "../js/diary/diaryHelper";
+import { useImperialConfig } from "../js/config/useImperialConfig";
+
+it('returns a formatted date', () => {
+  expect(getFormattedDate("2023-09-18T00:00:00-07:00")).toBe("Mon September 18, 2023");
+  expect(getFormattedDate("")).toBeUndefined();
+  expect(getFormattedDate("2023-09-18T00:00:00-07:00", "2023-09-21T00:00:00-07:00")).toBe("Mon September 18, 2023 - Thu September 21, 2023");
+});
+
+it('returns an abbreviated formatted date', () => {
+  expect(getFormattedDateAbbr("2023-09-18T00:00:00-07:00")).toBe("Mon, Sep 18");
+  expect(getFormattedDateAbbr("")).toBeUndefined();
+  expect(getFormattedDateAbbr("2023-09-18T00:00:00-07:00", "2023-09-21T00:00:00-07:00")).toBe("Mon, Sep 18 - Thu, Sep 21");
+});
+
+it('returns a human readable time range', () => {
+  expect(getFormattedTimeRange("2023-09-18T00:00:00-07:00", "2023-09-18T00:00:00-09:20")).toBe("2 hours");
+  expect(getFormattedTimeRange("2023-09-18T00:00:00-07:00", "2023-09-18T00:00:00-09:30")).toBe("3 hours");
+  expect(getFormattedTimeRange("", "2023-09-18T00:00:00-09:30")).toBeFalsy();
+});
+
+it("returns a MotionType object", () => {
+  expect(motionTypeOf("WALKING")).toEqual({ name: "WALKING", icon: "walk", color: '#0068a5' });
+  expect(motionTypeOf("MotionTypes.WALKING")).toEqual({ name: "WALKING", icon: "walk", color: '#0068a5' });
+  expect(motionTypeOf("I made this type up")).toEqual({ name: "UNKNOWN", icon: "help", color: '#484848'});
+});
+
+it('returns true/false is multi day', () => {
+  expect(isMultiDay("2023-09-18T00:00:00-07:00", "2023-09-19T00:00:00-07:00")).toBeTruthy();
+  expect(isMultiDay("2023-09-18T00:00:00-07:00", "2023-09-18T00:00:00-09:00")).toBeFalsy();
+  expect(isMultiDay("", "2023-09-18T00:00:00-09:00")).toBeFalsy();
+});
+
+//created a fake trip with relevant sections by examining log statements
+let myFakeTrip = {sections: [
+  { "sensed_mode_str": "BICYCLING", "distance": 6013.73657416706 },
+  { "sensed_mode_str": "WALKING", "distance": 715.3078629361006 }
+]};
+let myFakeTrip2 = {sections: [
+  { "sensed_mode_str": "BICYCLING", "distance": 6013.73657416706 },
+  { "sensed_mode_str": "BICYCLING", "distance": 715.3078629361006 }
+]};
+
+let myFakePcts = [
+  { mode: "BICYCLING",
+    icon: "bike",
+    color: '#007e46',
+    pct: 89 },
+  { mode: "WALKING",
+    icon: "walk",
+    color: '#0068a5',
+    pct: 11 }];
+
+let myFakePcts2 = [
+  { mode: "BICYCLING",
+    icon: "bike",
+    color: '#007e46',
+    pct: 100 }];
+
+it('returns the percetnages by mode for a trip', () => {
+  expect(getPercentages(myFakeTrip)).toEqual(myFakePcts);
+  expect(getPercentages(myFakeTrip2)).toEqual(myFakePcts2);
+  expect(getPercentages({})).toEqual({});
+})
+
diff --git a/www/js/diary/diaryHelper.ts b/www/js/diary/diaryHelper.ts
index 88dd9baa5..942268ec7 100644
--- a/www/js/diary/diaryHelper.ts
+++ b/www/js/diary/diaryHelper.ts
@@ -48,7 +48,7 @@ type MotionTypeKey = keyof typeof MotionTypes;
 export function motionTypeOf(motionName: MotionTypeKey | `MotionTypes.${MotionTypeKey}`) {
   let key = ('' + motionName).toUpperCase();
   key = key.split(".").pop(); // if "MotionTypes.WALKING", then just take "WALKING"
-  return MotionTypes[motionName] || MotionTypes.UNKNOWN;
+  return MotionTypes[key] || MotionTypes.UNKNOWN;
 }
 
 /**