diff --git a/CHANGELOG.md b/CHANGELOG.md
index 67a76e5e..aefee995 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -10,7 +10,8 @@ This project adheres to [Semantic Versioning](http://semver.org/).
 - Add `clientonly` script to start only the electron client for a remote server.
 - Add symbol and color properties of event when `CALENDAR_EVENTS` notification is broadcasted from `default/calendar` module.
 - Add `.vscode/` folder to `.gitignore` to keep custom Visual Studio Code config out of git.
-- Add unit test the capitalizeFirstLetter function of newfeed module
+- Add unit test the capitalizeFirstLetter function of newfeed module.
+- Add new unit tests for function `shorten` in calendar module.
 
 ### Updated
 - Changed 'default.js' - listen on all attached interfaces by default.
diff --git a/modules/default/calendar/calendar.js b/modules/default/calendar/calendar.js
index 06a47e4b..0b73fa49 100644
--- a/modules/default/calendar/calendar.js
+++ b/modules/default/calendar/calendar.js
@@ -424,25 +424,27 @@ Module.register("calendar", {
 		return defaultValue;
 	},
 
-	/* shorten(string, maxLength)
-	 * Shortens a string if it's longer than maxLength.
-	 * Adds an ellipsis to the end.
-	 *
-	 * argument string string - The string to shorten.
-	 * argument maxLength number - The max length of the string.
-	 * argument wrapEvents - Wrap the text after the line has reached maxLength
-	 *
-	 * return string - The shortened string.
+	/**
+	 * Shortens a string if it's longer than maxLength and add a ellipsis to the end
+	 * 
+	 * @param {string} string Text string to shorten
+	 * @param {number} maxLength The max length of the string
+	 * @param {boolean} wrapEvents Wrap the text after the line has reached maxLength
+	 * @returns {string} The shortened string
 	 */
 	shorten: function (string, maxLength, wrapEvents) {
-		if (wrapEvents) {
+		if (typeof string !== "string") {
+			return "";
+		}
+
+		if (wrapEvents === true) {
 			var temp = "";
 			var currentLine = "";
 			var words = string.split(" ");
 
 			for (var i = 0; i < words.length; i++) {
 				var word = words[i];
-				if (currentLine.length + word.length < 25 - 1) { // max - 1 to account for a space
+				if (currentLine.length + word.length < (typeof maxLength === "number" ? maxLength : 25) - 1) { // max - 1 to account for a space
 					currentLine += (word + " ");
 				} else {
 					if (currentLine.length > 0) {
@@ -454,12 +456,12 @@ Module.register("calendar", {
 				}
 			}
 
-			return temp + currentLine;
+			return (temp + currentLine).trim();
 		} else {
-			if (string.length > maxLength) {
-				return string.slice(0, maxLength) + "&hellip;";
+			if (maxLength && typeof maxLength === "number" && string.length > maxLength) {
+				return string.trim().slice(0, maxLength) + "&hellip;";
 			} else {
-				return string;
+				return string.trim();
 			}
 		}
 	},
diff --git a/tests/unit/functions/calendar_spec.js b/tests/unit/functions/calendar_spec.js
index be699847..3d65f497 100644
--- a/tests/unit/functions/calendar_spec.js
+++ b/tests/unit/functions/calendar_spec.js
@@ -29,10 +29,47 @@ describe("Functions into modules/default/calendar/calendar.js", function() {
 		};
 
 		Object.keys(words).forEach(word => {
-			it(`for ${word} should return ${words[word]}`, function() {
+			it(`for '${word}' should return '${words[word]}'`, function() {
 				expect(Module.definitions.calendar.capFirst(word)).to.equal(words[word]);
 			});
 		});
 	});
+
+	describe("shorten", function() {
+		strings = {
+			" String with whitespace at the beginning that needs trimming" : { length: 16, return: "String with whit&hellip;" },
+			"long string that needs shortening": { length: 16, return: "long string that&hellip;" },
+			"short string": { length: 16, return: "short string" },
+			"long string with no maxLength defined": { return: "long string with no maxLength defined" },
+		};
+
+		Object.keys(strings).forEach(string => {
+			it(`for '${string}' should return '${strings[string].return}'`, function() {
+				expect(Module.definitions.calendar.shorten(string, strings[string].length)).to.equal(strings[string].return);
+			});
+		});
+
+		it("should return an empty string if shorten is called with a non-string", function () {
+			expect(Module.definitions.calendar.shorten(100)).to.equal("");
+		});
+
+		it("should not shorten the string if shorten is called with a non-number maxLength", function () {
+			expect(Module.definitions.calendar.shorten("This is a test string", "This is not a number")).to.equal("This is a test string");
+		});
+
+		it("should wrap the string instead of shorten it if shorten is called with wrapEvents = true (with maxLength defined as 20)", function () {
+			expect(Module.definitions.calendar.shorten(
+				"This is a wrapEvent test. Should wrap the string instead of shorten it if called with wrapEvent = true",
+				20,
+				true)).to.equal("This is a <br>wrapEvent test. Should wrap <br>the string instead of <br>shorten it if called with <br>wrapEvent = true");
+		});
+
+		it("should wrap the string instead of shorten it if shorten is called with wrapEvents = true (without maxLength defined, default 25)", function () {
+			expect(Module.definitions.calendar.shorten(
+				"This is a wrapEvent test. Should wrap the string instead of shorten it if called with wrapEvent = true",
+				undefined,
+				true)).to.equal("This is a wrapEvent <br>test. Should wrap the string <br>instead of shorten it if called <br>with wrapEvent = true");
+		});
+	});
 });