Merge pull request #20 from passsy/feature/test_firstOrNull

Bugfix: Make firstOrNull return null for empty lists
passsy · Dec 6, 2018 · 0887669 · 0887669
2 parents f8d776d + 8368ef0
commit 0887669
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Showing 2 changed files with 22 additions and 1 deletion.
diff --git a/lib/src/extension/iterable_extension_mixin.dart b/lib/src/extension/iterable_extension_mixin.dart
@@ -360,7 +360,7 @@ abstract class KIterableExtensionsMixin<T>
       }
       final i = iterator();
       if (!i.hasNext()) {
-        throw NoSuchElementException("Collection is empty");
+        return null;
       }
       return i.next();
     } else {

diff --git a/test/collection/iterable_extensions_test.dart b/test/collection/iterable_extensions_test.dart
@@ -222,6 +222,27 @@ void testIterable(KIterable<T> Function<T>() emptyIterable,
     });
   });
 
+  group("firstOrNull", () {
+    if (ordered) {
+      test("get first element", () {
+        expect(iterableOf(["a", "b"]).firstOrNull(), "a");
+      });
+    } else {
+      test("get random first element", () {
+        var result = iterableOf(["a", "b"]).firstOrNull();
+        expect(result == "a" || result == "b", true);
+      });
+    }
+
+    test("firstOrNull returns null for empty", () {
+      expect(emptyIterable().firstOrNull(), isNull);
+    });
+
+    test("finds nothing throws", () {
+      expect(iterableOf<String>(["a"]).firstOrNull((it) => it == "b"), isNull);
+    });
+  });
+
   group("flatMap", () {
     test("flatMap int to string", () {
       final iterable = iterableOf([1, 2, 3]);