clean up logic; add test case

reverse.go

@@ -116,17 +116,12 @@ func Tail(file string, n int) ([]string, error) {
 	for i = n - 1; i >= 0; i-- {
 		lines[i], err = fh.ReadLine()
 		if err == io.EOF {
-			i++ // lines[i] is ""; we'll strip it
+			lines = lines[i+1:] // back it out
 			break
 		} else if err != nil {
 			return lines[i:], err
 		}
 	}
 
-	// See if number of lines < 'n'.
-	if i > 0 {
-		lines = lines[i:]
-	}
-
 	return lines, nil
 }

small.file

@@ -0,0 +1,2 @@
+This is a test file
+With just 2 lines.

tail_test.go

@@ -19,3 +19,17 @@ func TestTail(t *testing.T) {
 	}
 }
 
+func TestTailSmallFile(t *testing.T) {
+	fmt.Println("\n---------- TestTailSmallFile")
+	tail, err := Tail("small.file", 4)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(tail) != 2 {
+		t.Fatal("tail has len:", len(tail))
+	}
+	for i, s := range tail {
+		fmt.Println(i, ":", s)
+	}
+}
+