Support multiple occurrences of text in context

test/utils_test.dart

Index: test/utils_test.dart
diff --git a/test/utils_test.dart b/test/utils_test.dart
index a9988470938f39bd961ab14cf3aae8942dbd0567..74975c35bfbf771134a4bd3eb5ce1768884fe334 100644
--- a/test/utils_test.dart
+++ b/test/utils_test.dart
@@ -39,6 +39,45 @@ main() {
       }
     });
   });
+
+  group('find line start', () {
+    test('skip entries in wrong column', () {
+      var context = '0_bb\n1_bbb\n2b____\n3bbb\n';
+      var index = findLineStart(context, 'b', 1);
+      expect(index, 11);
+      expect(context.substring(index - 1, index + 3), '\n2b_');
+    });
+
+    test('end of line column for empty text', () {
+      var context = '0123\n56789\nabcdefgh\n';
+      var index = findLineStart(context, '', 5);
+      expect(index, 5);
+      expect(context[index], '5');
+    });
+
+    test('column at the end of the file for empty text', () {
+      var context = '0\n2\n45\n';
+      var index = findLineStart(context, '', 2);
+      expect(index, 4);
+      expect(context[index], '4');
+
+      context = '0\n2\n45';
+      index = findLineStart(context, '', 2);
+      expect(index, 4);
+    });
+
+    test('found on the first line', () {
+      var context = '0\n2\n45\n';
+      var index = findLineStart(context, '0', 0);
+      expect(index, 0);
+    });
+
+    test('not found', () {
+      var context = '0\n2\n45\n';
+      var index = findLineStart(context, '0', 1);
+      expect(index, isNull);
+    });
+  });
 }
 
 _linearSearch(list, predicate) {