Dynamodb unit testing with aws-sdk-go-v2

Question

I have a go project where I am having a query method called "queryMyTable". Here is the code for the method.

func queryMyTable(ctx context.Context, dynamodbClient *dynamodb.Client, tableName string, ids []string) (*dynamodb.QueryOutput, error) {

    // The filterExpression will be constructed based on the ids. Ex: "id IN (:id1,:id2)"
    filterExpression := constructFilterExpression(ids)

    // The expressionAttributeValues will be constructed based on the ids. 
    // It is of type map[string]types.AttributeValue
    // expressionAttributeValues = map[string]types.AttributeValue{
    //    "my-key": &types.AttributeValueS(Value: "my-key-value"),
    //    "id1": &types.AttributeValueS(Value: "111"),
    //    "id2": &types.AttributeValueS(Value: "222"),
    // }
    expressionAttributeValues := constructExpressionAttributeValues(ids)

    // Construct the query
    queryInput := &dynamodb.QueryInput{
        TableName:                 aws.String("my-ddb-table"),
        IndexName:                 aws.String("my-key-index"),
        KeyConditionExpression:    aws.String("my-key = :my-key"),
        FilterExpression:          aws.String(filterExpression),
        ExpressionAttributeValues: expressionAttributeValues,
        ProjectionExpression:      aws.String("id,list"),
    }

    // Execute the query
    result, err := dynamodbClient.Query(ctx, queryInput)
    if err != nil {
        return nil, err
    }

    // Return the results
    return result, nil
}

The sample data for the input parameters are: The filterExpression will be constructed based on the ids.

filterExpression = "id IN (:id1,:id2)"

The expressionAttributeValues will be constructed based on the ids.

expressionAttributeValues = map[string]types.AttributeValue{
  "my-key": &types.AttributeValueS(Value: "my-key-value"),
  "id1": &types.AttributeValueS(Value: "111"),
  "id2": &types.AttributeValueS(Value: "222"),
}

The code is working fine and I have written tests for constructFilterExpression and constructExpressionAttributeValues.

Now, I want to write unit test cases for this method. I am using "aws-sdk-go-v2" and I am not sure how to mock a dynamodb client and setup data for my tests and execute the query method against the mock data.

I tried with this test code

// MockDynamoDBClient is a mock implementation of the DynamoDB client
type MockDynamoDBClient struct {
    dynamodb.Client
    QueryFunc          func(ctx context.Context, params *dynamodb.QueryInput, optFns ...func(*dynamodb.Options)) (*dynamodb.QueryOutput, error)
    QueryRequestInput  *dynamodb.QueryInput
    QueryResponseData  *dynamodb.QueryOutput
    QueryResponseError error
}

// Query mocks the Query method of the DynamoDB client
func (m *MockDynamoDBClient) Query(ctx context.Context, params *dynamodb.QueryInput, optFns ...func(*dynamodb.Options)) (*dynamodb.QueryOutput, error) {
    if m.QueryFunc != nil {
        return m.QueryFunc(ctx, params, optFns...)
    }

    // Store the executed query parameters for assertions in the test
    m.QueryRequestInput = params

    // Return the stored response data or error
    return m.QueryResponseData, m.QueryResponseError
}

But when I executed my query method inside the test method it gave me error obviously

output, err := queryVPNConfigurations(context.Background(), &mockClient.Client, "test-table-name", []string{"111","222"})

Error: operation error DynamoDB: Query, expected endpoint resolver to not be nil. Then I tried setup and endpointresolver and failed again. I am not sure, if this is the way it has to be done.

Any help is appreciated.