Add tests for iter module (#188)

This should get module-level coverage to 100%

Author: tarcieri

src/iter.rs

@@ -105,3 +105,28 @@ where
         self.iter_mut()
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use crate::{Array, sizes::U3};
+
+    #[test]
+    fn mut_array_ref_into_iterator() {
+        let array_ref: &mut Array<u8, U3> = &mut Array([1, 2, 3]);
+        let mut iter = array_ref.into_iter();
+
+        for i in 1..=3 {
+            assert_eq!(iter.next().copied(), Some(i));
+        }
+
+        assert_eq!(iter.next(), None);
+    }
+
+    #[cfg(feature = "alloc")]
+    #[test]
+    fn display_try_from_iterator_error() {
+        use super::TryFromIteratorError;
+        use alloc::string::ToString;
+        let _ = TryFromIteratorError.to_string();
+    }
+}