diff --git a/lib/utils.js b/lib/utils.js
index b8e7e1802..13fae7e5b 100644
--- a/lib/utils.js
+++ b/lib/utils.js
@@ -5,8 +5,15 @@ import { isStream } from "is-stream";
 export function collectStream(source, callback) {
   var collection = [];
   var size = 0;
+  var done = false;
 
-  source.on("error", callback);
+  source.on("error", function (err) {
+    if (done) {
+      return;
+    }
+    done = true;
+    callback(err);
+  });
 
   source.on("data", function (chunk) {
     collection.push(chunk);
@@ -14,6 +21,11 @@ export function collectStream(source, callback) {
   });
 
   source.on("end", function () {
+    if (done) {
+      return;
+    }
+    done = true;
+
     var buf = Buffer.alloc(size);
     var offset = 0;
 
diff --git a/test/utils.js b/test/utils.js
new file mode 100644
index 000000000..caed20327
--- /dev/null
+++ b/test/utils.js
@@ -0,0 +1,88 @@
+import { EventEmitter } from "events";
+import { Readable } from "readable-stream";
+import { assert } from "chai";
+import {
+  collectStream,
+  dateify,
+  normalizeInputSource,
+  sanitizePath,
+  trailingSlashIt,
+} from "../lib/utils.js";
+
+describe("utils", function () {
+  describe("collectStream", function () {
+    it("should collect data chunks from a stream into a buffer", function (done) {
+      var source = new Readable({
+        read() {
+          this.push(Buffer.from("hello "));
+          this.push(Buffer.from("world"));
+          this.push(null);
+        },
+      });
+
+      collectStream(source, function (err, buf) {
+        assert.isNull(err);
+        assert.instanceOf(buf, Buffer);
+        assert.equal(buf.toString(), "hello world");
+        done();
+      });
+    });
+
+    it("should handle stream error events", function (done) {
+      var source = new EventEmitter();
+
+      collectStream(source, function (err, buf) {
+        assert.isNotNull(err);
+        assert.equal(err.message, "stream error");
+        assert.isUndefined(buf);
+        done();
+      });
+
+      source.emit("error", new Error("stream error"));
+    });
+
+    it("should not invoke callback twice if stream emits error and then end", function (done) {
+      var source = new EventEmitter();
+      var callCount = 0;
+
+      collectStream(source, function (err) {
+        callCount++;
+        assert.equal(callCount, 1, "callback should only be called once");
+        assert.isNotNull(err);
+        assert.equal(err.message, "stream error");
+
+        // Wait slightly to ensure subsequent 'end' event does not trigger callback again
+        setTimeout(function () {
+          assert.equal(callCount, 1);
+          done();
+        }, 50);
+      });
+
+      source.emit("error", new Error("stream error"));
+      source.emit("end");
+    });
+  });
+
+  describe("dateify", function () {
+    it("should return Date instance", function () {
+      var d = dateify("2020-01-01T00:00:00.000Z");
+      assert.instanceOf(d, Date);
+      assert.equal(d.toISOString(), "2020-01-01T00:00:00.000Z");
+    });
+  });
+
+  describe("sanitizePath", function () {
+    it("should strip drive letters and leading slashes", function () {
+      assert.equal(sanitizePath("c:/test/path.txt"), "test/path.txt");
+      assert.equal(sanitizePath("/root/file.txt"), "root/file.txt");
+      assert.equal(sanitizePath("../relative/file.txt"), "relative/file.txt");
+    });
+  });
+
+  describe("trailingSlashIt", function () {
+    it("should add trailing slash if missing", function () {
+      assert.equal(trailingSlashIt("foo/bar"), "foo/bar/");
+      assert.equal(trailingSlashIt("foo/bar/"), "foo/bar/");
+    });
+  });
+});