Add tests from fuzzing

Add test from fuzzing samples in image-rs#28, image-rs#29 and image-rs#31

tests/fuzz_tests.rs

@@ -0,0 +1,42 @@
+extern crate tiff;
+
+use tiff::{TiffResult, ColorType};
+use tiff::decoder::{Decoder, DecodingResult, ifd::Tag, ifd::Value};
+
+use std::fs::File;
+
+fn test_directory<F: Fn(File) -> bool>(path: &str, f: F) {
+    for entry in std::fs::read_dir(path).unwrap() {
+        let file = File::open(entry.unwrap().path()).unwrap();
+        assert!(f(file));
+    }
+}
+
+fn decode_tiff(file: File) -> TiffResult<()> {
+    let mut decoder = Decoder::new(file)?;
+    decoder.read_image()?;
+    Ok(())
+}
+
+#[test]
+fn oor_panic() {
+    test_directory("./tests/fuzz_images/oor_panic", |file| {
+        decode_tiff(file).ok();
+        true
+    });
+}
+
+#[test]
+fn oom_crash() {
+    test_directory("./tests/fuzz_images/oom_crash", |file| {
+        decode_tiff(file).is_err()
+    });
+}
+
+#[test]
+fn inf_loop() {
+    test_directory("./tests/fuzz_images/inf_loop", |file| {
+        decode_tiff(file).ok();
+        true
+    });
+}