Add test for failing edge-case images with subtitles

Closes #29

CHANGELOG.md

@@ -1,6 +1,7 @@
 **Version 0.2.1**
  - Add rustdoc for public methods and structs
  - Improve filter mode 5 heuristic ([#16](https://github.com/shssoichiro/oxipng/issues/16))
+ - Add tests for edge-case images with subtitles ([#29](https://github.com/shssoichiro/oxipng/issues/29))
 
 **Version 0.2.0**
  - Fix program version that is displayed when running `oxipng -V`

tests/filters.rs

@@ -1209,3 +1209,20 @@ fn filter_5_for_palette_1() {
                      png::ColorType::Indexed,
                      png::BitDepth::One);
 }
+
+#[test]
+fn issue_29() {
+    let input = PathBuf::from("tests/files/issue-29.png");
+    let mut opts = get_opts(&input);
+    opts.filter = HashSet::new();
+    opts.filter.insert(0);
+    let output = opts.out_file.clone();
+
+    test_it_converts(&input,
+                     &output,
+                     &opts,
+                     png::ColorType::RGB,
+                     png::BitDepth::Eight,
+                     png::ColorType::RGB,
+                     png::BitDepth::Eight);
+}