jboursiquot/baltimorego-jan-8.md Secret

## baltimorego-jan-8.md

      
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              baltimorego-jan-8.md
            
          
    Working with Interfaces

This exercise challenges you to think about how to use interfaces to mock third party behavior.
Imagine you have a project that needs to interact with AWS DynamoDB. AWS makes available a Go SDK and package for such a purpose: dynamodb.
Your starting point is a package mypackage containing a custom type DynamoDBSaver with a Save method:
package mypackage

type DynamoDBSaver struct {
	// dynamodb client here
}

func (s *DynamoDBSaver) Save(ctx context.Context, p *Person) error {
	item, err := dynamodbattribute.MarshalMap(p)
	if err != nil {
		return fmt.Errorf("failed to marshal shoutout for storage: %s", err)
	}

	input := &dynamodb.PutItemInput{
		Item:      item,
		TableName: aws.String(os.Getenv("TABLE_NAME")),
	}
	
 // your code to PutItemWithContext here
}

A value of type Person is also expected in the Save call.
type Person struct {
	Name string
}

AWS also makes available a package for the DynamoDB API that you can use in your tests: dynamodbiface. Your task is to mock out the DynamoDB API for your DynamoDBSaver to use in tests.

Hint: Use Go interfaces to mock only what you need.

You will also need to include the dynamodbattrbiute package in your imports.
Success Criteria:

You mock the DynamoDB API in your tests
You test your package from outside of your mypackage package (i.e. mypackage_test)
Bonus: You use table-driven testing technique

Learning Outcomes:

You know how to set up Go tests
You know how to work with third party packages
You know how to use Go interfaces effectively
You know how to mock only what you need