![[Flutter] Fix Contains invalid characters error in http test](/assets/images/category/flutter/background.avif)
Outline
When you call an API in Flutter, you use the http package normally. For how to call API using the http package in Flutter, please refer to the link below.
When you test the code implemented with the http package, the Contains invalid characters error often occurs. In this blog post, I will introduce how to fix the Contains invalid characters error that occurs when you test the code implemented with the http package.
Contains invalid characters error
When you write the test code, if the Response contains a language other than English, the Contains invalid characters error occurs as follows.
when(mockHttpClient.post(
Uri.parse('${ENV.apiServer}/api/logout'),
headers: anyNamed('headers'),
)).thenAnswer((_) async => http.Response('''{
"success": true,
"data": {
"message": "ログアウトしました。"
},
"errors": null
}''', 200));
In this blog post, I returned a Response that contains Japanese. When you run this test code, you can see that the Contains invalid characters error occurs as follows.
Invalid argument (string): Contains invalid characters.: "{\n \"success\": true,\n \"data\": {\n \"message\": \"ログアウトしました。\"\n },\n \"errors\": null\n }"
dart:convert Latin1Codec.encode
package:http/src/response.dart 37:49 new Response
How to fix
To fix this problem, you need to encode the Response using http.Response.bytes and utf8.encode as follows.
when(mockHttpClient.post(
Uri.parse('${ENV.apiServer}/api/logout'),
headers: anyNamed('headers'),
)).thenAnswer((_) async => http.Response.bytes(utf8.encode('''{
"success": true,
"data": {
"message": "ログアウトしました。"
},
"errors": null
}'''), 200));
When you modify the test code like this and run it, you can see that the test code is passed without any problems.
Completed
Done! We’ve seen how to fix the Contains invalid characters error that occurs when you test the feature implemented by the http package in Flutter. If you have a Contains invalid characters error, please refer to this blog post to fix it.
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