error_case

Description:

error case

Error Case #
Welcome to the error_case library. A library to define error cases that we can use to test our code.
Features #

Data class validation
Empty string validation
Minimum number validation
Maximum number validation
More to come in the future...

How to use #
Let's start with an example of a data class.
class User implements JsonModel {

User(this.id, this.name, this.address, this.age);

final String id;
final String name;
final Map<String, String> address;
final int age;

factory User.fromJson(Map<String, dynamic> json) =>
_$UserItemFromJson(json);

@override
Map<String, dynamic> toJson() => _$UserItemToJson(this);
}
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In our data class User we have id, name, address, age properties.
This will be our sample data class throughout the guide.
It is important to note that this implements JsonModel a class that contains fromJson() & toJson() functions.
In this example I am also using json_serializable to generate fromJson & toJson functions.
class InvalidUserModelErrorCase extends ObjectSingleErrorCase {

InvalidUserModelErrorCase(): super(
['id', 'name', 'address.country', age], // Required properties
minimumValue: {'age': 21},
maximumValue: {'age': 200}
);
}

// P.S. There's a shorter way to implement this but we need Dart 2.16
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In our error case we've defined our required fields id, name, address.country, age.
What is address.country? This defines a nested lookup that validates the keys it passes through and value at the end.
If we don't include a property of the class. It will be considered optional, no validation will happened to that property.
Let's see a brief example of how we use these classes we've written.
void main() {

final user = User( // Here's a sample User class
'ABCD1234', // id
'David Hamster', // name
{'country': 'Kingdom of Nocturnia'}, // address map
24 // age
);

const errorCase = InvalidUserModelErrorCase();

errorCase.validate(user,
_onInvalidUserModel,
_onValidUserModel);
}

void _onInvalidUserModel(Exception ex) {
// 'ex' can be a child of ErrorCaseException or a different Exception altogether.
}

void _onValidUserModel(User user) {
// When there are no errors, the data that was validated will be passed on as a parameter for this function.
}
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To summarize the example above.

We have a user class with data.
We create a const of an Error case.
We then call .validate() and pass data, errorFunction, successFunction.

Non Returning Error Cases #
These are error cases that do not expect a return value on the error and success functions.
Classes

SingleErrorCase
ObjectSingleErrorCase

See error_case_test.dart
Returning Error Cases #
These are error cases that expect a return value on the error and success functions.
Classes

SingleErrorReturnCase
ObjectSingleErrorReturnCase

See error_case_return_test.dart
Good Practices #
DO: Create a new error case class for a specific scenario. Just like when defining a Use Case for specific business logics.
DONT: Combine with other scenarios. This will make it difficult to locate where the error is happening when on reports.
--
DO: Declare a new instance of an error case with const for compile time benefits.
DONT: Declare a new instance of an error case without const on the UI code because it can be recreated.
Developed by #

Edamama
Edamama Github Org

Contributors #

Azma Ahmed
Gian Patrick Quintana
Harsh Chaurasia
Omkar Gaikwad
Pruitvi Sandiri
Reyster Fresco
Shiv Pratap Singh
Shubhanshu Singh