Add new tests, fix bugs with Differ

tests/test.rs

@@ -1,7 +1,7 @@
 extern crate difflib;
 
-use difflib::sequencematcher::{SequenceMatcher, Match};
-
+use difflib::sequencematcher::{SequenceMatcher, Match, Opcode};
+use difflib::differ::Differ;
 
 #[test]
 fn test_longest_match()
@@ -35,4 +35,69 @@ fn test_all_matches()
     	size: 0
     });
     assert_eq!(result, expected_result);
+}
+
+#[test]
+fn test_get_opcodes() {
+    let mut matcher = SequenceMatcher::new("qabxcd", "abycdf");
+    let result = matcher.get_opcodes();
+    let mut expected_result = Vec::new();
+    expected_result.push(Opcode{
+        tag: "delete".to_string(),
+        first_start: 0,
+        first_end: 1,
+        second_start: 0,
+        second_end: 0
+    });
+    expected_result.push(Opcode{
+        tag: "equal".to_string(),
+        first_start: 1,
+        first_end: 3,
+        second_start: 0,
+        second_end: 2
+    });
+    expected_result.push(Opcode{
+        tag: "replace".to_string(),
+        first_start: 3,
+        first_end: 4,
+        second_start: 2,
+        second_end: 3
+    });
+    expected_result.push(Opcode{
+        tag: "equal".to_string(),
+        first_start: 4,
+        first_end: 6,
+        second_start: 3,
+        second_end: 5
+    });
+    expected_result.push(Opcode{
+        tag: "insert".to_string(),
+        first_start: 6,
+        first_end: 6,
+        second_start: 5,
+        second_end: 6
+    });
+    assert_eq!(result, expected_result);
+}
+
+#[test]
+fn test_ratio() {
+    let mut matcher = SequenceMatcher::new("abcd", "bcde");
+    assert_eq!(matcher.ratio(), 0.75);
+}
+
+#[test]
+fn test_get_close_matches() {
+    let words = vec!["ape", "apple", "peach", "puppy"];
+    let result = difflib::get_close_matches("appel", words, 3, 0.6);
+    assert_eq!(result, vec!["apple", "ape"]);
+}
+
+#[test]
+fn test_differ_compare() {
+    let first_text = vec!["one\n", "two\n", "three\n"];
+    let second_text = vec!["ore\n", "tree\n", "emu\n"];
+    let differ = Differ::new();
+    let result = differ.compare(&first_text, &second_text).join("");
+    assert_eq!(result, "- one\n?  ^\n+ ore\n?  ^\n- two\n- three\n?  -\n+ tree\n+ emu\n");
 }