fix uppercase diff names bug

add DiffNames tests

niivue/src/utility.ts

@@ -29,8 +29,8 @@ export function differenceInNames(names: string[], rec = true) {
   // if startCommon points to a letter then include all preceding letters as well
   while (
     startCommon > 0 &&
-    names[0].slice(startCommon - 1, startCommon) >= 'a' &&
-    names[0].slice(startCommon - 1, startCommon) <= 'z'
+    names[0].slice(startCommon - 1, startCommon).toLowerCase() >= 'a' &&
+    names[0].slice(startCommon - 1, startCommon).toLowerCase() <= 'z'
   ) {
     startCommon -= 1
   }

niivue/test/DiffNames.test.ts

@@ -0,0 +1,21 @@
+import { describe, expect, it, test } from 'vitest'
+import { differenceInNames } from '../src/utility'
+
+test('diff names of test and test2', () => {
+  expect(differenceInNames(['test', 'test2'])).toEqual(['test', 'test2'])
+  expect(differenceInNames(['test1', 'test2'])).toEqual(['test1', 'test2'])
+  expect(
+    differenceInNames(['verysuperendlesslongnametest1', 'verysuperendlesslongnametest2']),
+  ).toEqual(['verysuperendlesslongnametest1', 'verysuperendlesslongnametest2'])
+  expect(differenceInNames(['test1.nii', 'test2.nii'])).toEqual(['test1', 'test2'])
+  expect(differenceInNames(['qsm_test1', 'qsm_test2'])).toEqual(['test1', 'test2'])
+  expect(differenceInNames(['/folder1/qsm_test1', '/folder2/qsm_test2'])).toEqual([
+    'folder1 - test1',
+    'folder2 - test2',
+  ])
+  expect(differenceInNames(['/folder1/qsm_test', '/folder2/qsm_test'])).toEqual([
+    'folder1',
+    'folder2',
+  ])
+  expect(differenceInNames(['Glu.nii.gz', 'Gln.nii.gz'])).toEqual(['Glu', 'Gln'])
+})