TypeScript Type Alias to Builder Class

TypeScript Type Alias to Builder Class is a Visual Studio Code extension that will save you time by automatically generating a builder class from a TypeScript type alias.

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Features

Stop wasting time manually writing out builder classes. Use this extension to instantly generate a builder from a type alias.

The generated file will be in the same folder as your type alias file.

If you're not already using builders, you should start. They are a great way to easily generate data for your unit tests.

If you are using this extension and find any issues or wish to add improvements, feel free to contribute.

Example

Here is an example of using the generated builder to create a user for a test scenario.

Start with an type alias file that you have written.

user.type.ts

export type User = {
  firstName: string
  lastName: string
  email: string
  age: number
}

Run the extension Cmd/Ctrl + Shift + P => Generate Builder Class From TypeScript Type Alias.

Manually update the generated file to take care of any required imports and to set the default values.

To create a new user with the default values defined in the builder class use the following code.

const user: User = new UserBuilder().build()

If you want to override the default values you can specify unique values using .with<PropertyName>(value).

const user: User = new UserBuilder()
  .withFirstName('Bruce')
  .withLastName('Wayne')
  .withEmail('bruce.wayne@wayne-enterprises.com')
  .WithAge(48)
  .build()

Requirements

To use the extension:

• You must have a folder open in Visual Studio Code
• You must have a type alias file open
• Your type alias must include the text export type
• You need to have at least one property defined with a data type e.g. firstName: string

Known Issues

• Any required imports will have to be added manually after the builder is generated.
• If your property has an Advanced Type e.g. foo: keyof Foo the initial value will be undefined which will not compile unless the property is optional. These values will need to manually entered.
• If you have methods defined in your type alias the builder will not be generated.