Support multiple occurrences of text in context

test/span_test.dart

Index: test/span_test.dart
diff --git a/test/span_test.dart b/test/span_test.dart
index 39b0b9433ddc779998867a97ec8ebd60f77e7575..2657f5ffdbaea00318b97b9c05abcbbfbcf67627 100644
--- a/test/span_test.dart
+++ b/test/span_test.dart
@@ -65,6 +65,21 @@ main() {
         new SourceSpanWithContext(start, end, "abc", "\n---abc--");
         new SourceSpanWithContext(start, end, "abc", "\n\n---abc--");
       });
+
+      test('text can occur multiple times in context', () {
+        var start1 = new SourceLocation(4, line: 55, column: 2);
+        var end1 = new SourceLocation(7, line: 55, column: 5);
+        var start2 = new SourceLocation(4, line: 55, column: 8);
+        var end2 = new SourceLocation(7, line: 55, column: 11);
+        new SourceSpanWithContext(start1, end1, "abc", "--abc---abc--\n");
+        new SourceSpanWithContext(start1, end1, "abc", "--abc--abc--\n");
+        new SourceSpanWithContext(start2, end2, "abc", "--abc---abc--\n");
+        new SourceSpanWithContext(start2, end2, "abc", "---abc--abc--\n");
+        expect(() => new SourceSpanWithContext(
+              start1, end1, "abc", "---abc--abc--\n"), throwsArgumentError);
+        expect(() => new SourceSpanWithContext(
+              start2, end2, "abc", "--abc--abc--\n"), throwsArgumentError);
+      });
     });
 
     group('for union()', () {
@@ -238,6 +253,18 @@ line 1, column 6 of foo.dart: oh no
      ${colors.YELLOW}^^^^^^^${colors.NONE}"""));
     });
 
+    test("underlines correctly when text appears twice", () {
+      var span = new SourceSpanWithContext(
+          new SourceLocation(9, column: 9, sourceUrl: "foo.dart"),
+          new SourceLocation(12, column: 12, sourceUrl: "foo.dart"),
+          "foo",
+          "-----foo foo-----");
+      expect(span.message("oh no", color: colors.YELLOW), equals("""
+line 1, column 10 of foo.dart: oh no
+-----foo ${colors.YELLOW}foo${colors.NONE}-----
+         ${colors.YELLOW}^^^${colors.NONE}"""));
+  });
+
     test("supports lines of preceeding context", () {
       var span = new SourceSpanWithContext(
           new SourceLocation(5, line: 3, column: 5, sourceUrl: "foo.dart"),