From d16f49db298514f27633cfd208efe007c24b25a8 Mon Sep 17 00:00:00 2001
From: yagni <yagni@users.noreply.github.com>
Date: Thu, 15 Sep 2022 13:29:28 -0500
Subject: [PATCH] fix: isPrivateTag no longer silently returns false when given
 a tag whose last digit in the group is a hex digit.

Note: Direct calls to isPrivateTag can now throw a string as an exception if the tag is corrupt.
---
 src/util/util.js  |  7 +++++--
 test/util_test.js | 11 ++++++++++-
 2 files changed, 15 insertions(+), 3 deletions(-)

diff --git a/src/util/util.js b/src/util/util.js
index 5dd140f..4428a63 100644
--- a/src/util/util.js
+++ b/src/util/util.js
@@ -41,12 +41,15 @@ const isStringVr = (vr) => stringVrs[vr];
  * Tests to see if a given tag in the format xggggeeee is a private tag or not
  * @param tag
  * @returns {boolean}
+ * @throws error if fourth character cannot be parsed
  */
 const isPrivateTag = (tag) => {
-  const lastGroupDigit = parseInt(tag[4], 10);
+  const lastGroupDigit = parseInt(tag[4], 16);
+  if (isNaN(lastGroupDigit)) {
+    throw 'dicomParser.isPrivateTag: cannot parse last character of group';
+  }
   const groupIsOdd = (lastGroupDigit % 2) === 1;
 
-
   return groupIsOdd;
 };
 
diff --git a/test/util_test.js b/test/util_test.js
index 6d6e478..8de0414 100644
--- a/test/util_test.js
+++ b/test/util_test.js
@@ -6,7 +6,7 @@ describe('util', () => {
   describe('#isPrivateTag', () => {
 
     it('should return `true` for a private tag', () => {
-      const isPrivateTag = util.isPrivateTag('x00190010');
+      const isPrivateTag = util.isPrivateTag('x001d0010');
       expect(isPrivateTag).to.equal(true);
     })
 
@@ -15,6 +15,15 @@ describe('util', () => {
       expect(isPrivateTag).to.equal(false);
     })
 
+    it('should throw an exception', () => {
+      // Arrange
+      const tag = 'x100z0010';
+      const invoker = () => util.isPrivateTag(tag);
+
+      // Act / Assert
+      expect(invoker).to.throw();
+    });
+
   });
 
   describe('#parsePN', () => {