emailjs_test: add testing for library

Author: Sergey Khomushin

test/emailjs_test.dart

@@ -0,0 +1,114 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:mocktail/mocktail.dart';
+import 'package:http/http.dart' as http;
+
+import 'package:emailjs/emailjs.dart';
+
+class MockClient extends Mock implements http.Client {}
+
+class FakeUri extends Fake implements Uri {}
+
+void main() {
+  setUpAll(() {
+    registerFallbackValue(FakeUri());
+  });
+
+  group('required params validator', () {
+    test('should send method and fail on the public key', () {
+      expect(
+        () => EmailJS.send('default_service', 'my_test_template'),
+        throwsA(startsWith('The public key is required')),
+      );
+    });
+
+    test('should send method and fail on the service ID', () {
+      EmailJS.init('LC2JWGTestKeySomething');
+
+      expect(
+        () => EmailJS.send('', 'my_test_template'),
+        throwsA(startsWith('The service ID is required')),
+      );
+    });
+
+    test('should send method and fail on the template ID', () {
+      EmailJS.init('LC2JWGTestKeySomething');
+
+      expect(
+        () => EmailJS.send('default_service', ''),
+        throwsA(startsWith('The template ID is required')),
+      );
+    });
+  });
+
+  group('EmailJS.send method', () {
+    test('should init and send method successfully', () async {
+      final mockHttpClient = MockClient();
+
+      when(() => mockHttpClient.post(
+            any(),
+            headers: any(named: 'headers'),
+            body: any(named: 'body'),
+          )).thenAnswer((_) async => http.Response('OK', 200));
+
+      EmailJS.init('LC2JWGTestKeySomething', null, mockHttpClient);
+
+      try {
+        final result = await EmailJS.send(
+          'default_service',
+          'my_test_template',
+        );
+        expect(result, equals('OK'));
+      } catch (error) {
+        expect(error, isNull);
+      }
+    });
+
+    test('should send method successfully with 4 params', () async {
+      final mockHttpClient = MockClient();
+
+      when(() => mockHttpClient.post(
+            any(),
+            headers: any(named: 'headers'),
+            body: any(named: 'body'),
+          )).thenAnswer((_) async => http.Response('OK', 200));
+
+      // pass the mock http client
+      EmailJS.init('', null, mockHttpClient);
+
+      try {
+        final result = await EmailJS.send(
+          'default_service',
+          'my_test_template',
+          null,
+          'LC2JWGTestKeySomething',
+        );
+        expect(result, equals('OK'));
+      } catch (error) {
+        expect(error, isNull);
+      }
+    });
+
+    test('should send method and fail', () async {
+      final mockHttpClient = MockClient();
+
+      when(() => mockHttpClient.post(
+        any(),
+        headers: any(named: 'headers'),
+        body: any(named: 'body'),
+      )).thenAnswer((_) async => http.Response('The Public Key is required', 403));
+
+      // pass the mock http client
+      EmailJS.init('LC2JWGTestKeySomething', null, mockHttpClient);
+
+      try {
+        final result = await EmailJS.send(
+          'default_service',
+          'my_test_template',
+        );
+        expect(result, isNull);
+      } catch (error) {
+        expect(error, equals('The Public Key is required'));
+      }
+    });
+  });
+}