add BarcodeFormat test

+import 'package:flutter_test/flutter_test.dart';
+import 'package:mobile_scanner/src/enums/barcode_format.dart';
+
+void main() {
+  group('$BarcodeFormat tests', () {
+    test('can be created from raw value', () {
+      const values = <int, BarcodeFormat>{
+        -1: BarcodeFormat.unknown,
+        0: BarcodeFormat.all,
+        1: BarcodeFormat.code128,
+        2: BarcodeFormat.code39,
+        4: BarcodeFormat.code93,
+        8: BarcodeFormat.codebar,
+        16: BarcodeFormat.dataMatrix,
+        32: BarcodeFormat.ean13,
+        64: BarcodeFormat.ean8,
+        128: BarcodeFormat.itf,
+        256: BarcodeFormat.qrCode,
+        512: BarcodeFormat.upcA,
+        1024: BarcodeFormat.upcE,
+        2048: BarcodeFormat.pdf417,
+        4096: BarcodeFormat.aztec,
+      };
+
+      for (final MapEntry<int, BarcodeFormat> entry in values.entries) {
+        final BarcodeFormat result = BarcodeFormat.fromRawValue(entry.key);
+
+        expect(result, entry.value);
+      }
+    });
+
+    test('invalid raw value creates unknown barcode format', () {
+      final BarcodeFormat negative = BarcodeFormat.fromRawValue(-2);
+      final BarcodeFormat outOfRange = BarcodeFormat.fromRawValue(4097);
+
+      expect(negative, BarcodeFormat.unknown);
+      expect(outOfRange, BarcodeFormat.unknown);
+    });
+
+    test('can be converted to raw value', () {
+      const values = <BarcodeFormat, int>{
+        BarcodeFormat.unknown: -1,
+        BarcodeFormat.all: 0,
+        BarcodeFormat.code128: 1,
+        BarcodeFormat.code39: 2,
+        BarcodeFormat.code93: 4,
+        BarcodeFormat.codebar: 8,
+        BarcodeFormat.dataMatrix: 16,
+        BarcodeFormat.ean13: 32,
+        BarcodeFormat.ean8: 64,
+        BarcodeFormat.itf: 128,
+        BarcodeFormat.qrCode: 256,
+        BarcodeFormat.upcA: 512,
+        BarcodeFormat.upcE: 1024,
+        BarcodeFormat.pdf417: 2048,
+        BarcodeFormat.aztec: 4096,
+      };
+
+      for (final MapEntry<BarcodeFormat, int> entry in values.entries) {
+        final int result = entry.key.rawValue;
+
+        expect(result, entry.value);
+      }
+    });
+  });
+}