faupi

Blazingly fast API Mock Server written in Rust.

Table of Contents

• Installation
• Usage
• Specification
  • Specification URL
  • Specification response
    • Specification response body
  • Specification example
• Import OpenAPI specification
• Links

Installation

Currently there's no other way of installing then building it yourself. You need to have Rust Toolchain installed (see rust installation page). When you have the Rust Toochain, you can build the project with cargo:

cargo build -r

After it's done compiling, the binary will be target/release/faupi.

Usage

Note: In all the examples, the path to the project binary is substituted by faupi.

To run the actual Mock API server, you can start it by running:

faupi serve -s specs.yaml
faupi serve -s specs.yaml -a 123.345.67.89 -p 1234

where the specs.yaml contains the specification of the Mock API. More about that in the specification section. The second command showcases running the server on custom address and port.

More details about all the functionality can be found in the help:

faupi -h

Import OpenAPI specification

Note: this only supports basic OpenAPI specification files

If you already have an OpenAPI specification file, you can import it with faupi and convert it to the faupi specification file. You can do it like this:

faupi import -i docs.jsonopenapi -o faupi-spec.yaml

Specification

Specification is either .yaml or .json file. It contains list of endpoint specifications. Each endpoint specification sets what the API Mock server should respond on each URL with different HTTP methods. The endpoint specification contains:

• HTTP method (method)
  • Get, Head, Post, Put, Delete, Connect, Options, Trace, Path
• Endpoint URL (url)
  • See specification URL.
• Response (response) - optional
  • See specification response.

Specification URL

URL in the specification can be normal URL string, such as /api/example/36. This URL has hardcoded ID, which is not ideal for API testing. For this purpose, faupi contains option to add parameters into the URL.

To add parameter to the URL, you have to enclose the parameter definition in the curly brackets. Variable definition consists of name and optional type - type defaults to string. If we parametrize the mentioned URL, we get /api/example/{id: number}.

In the above example, we used the type number, which suits the ID better. Currently supported URL parameter types are:

• string
• number

Specification response

Specification response corresponds to the HTTP response returned by the API Mock server. It contains:

• HTTP response status (status) - defaults to 200.
  • 200 = OK, 404 = Not Found,...
• HTTP response delay (delay) - defaults to no delay.
  • Time the server waits before sending response (in milliseconds).
• HTTP response body (body) - defaults to null.
  • See specification response body.

Specification response body

To be able to support more dynamic responses, response body supports variables. Currently only way to set the variables is from the URL parameters.

To use a variable inside of a body value, you can add $ followed by the variable name (such as $name). To prevent ambiguity, you can also wrap the variable name inside of curly brackets (${name}) - this way you can chain a variable and static string after each other without having to use a space.

faupi also supports generating random variable values. It contains a special object-like variable - fake. You can then use one of the built-in object attributes to generate random value, such as first name, last name, profesion and more. You use it as a normal variable with $ - $fake.name. To see all the fake object attributes, visit fake object section.

Specification example

To add API GET endpoint on URL /api/example/{id:number}, we can add this endpoint specification to out specification file:

- method: Get
  url: /api/example/{id:number}
  response:
    status: 200
    body:
      id: $id
      message: Hope you like faupi!
      review: $fake.name recommends using it.

This endpoint specification returns response with HTTP response status 200 - OK and body contains object with attributes id and message. The message contains static string, but the id gets expanded to the URL id parameter value. For example, when API receives HTTP request with URL /api/example/36, the response body will contain object with id set to 36.

Fake object

Address

Attribute	Description
building_number	Random building number
city_name	Random city name
city_prefix	Random city prefix
city_suffix	Random city suffix
country_code	Random country code
latitude	Random latitude
longitude	Random longitude
post_code	Random postal code
secondary_address	Random secondary address
secondary_address_type	Random secondary address type
state_abbr	Random state abbreviation
state_name	Random state name
street_name	Random street name
street_suffix	Random street suffix
time_zone	Random time zone
zip_code	Random ZIP code

Barcode

Attribute	Description
isbn	Random ISBN
isbn10	Random ISBN-10
isbn13	Random ISBN-13

Company

Attribute	Description
bs	Random business slogan
bs_adj	Random business adjective
bs_noun	Random business noun
bs_verb	Random business verb
buzzword	Random buzzword
buzzword_middle	Random buzzword middle word
buzzword_tail	Random buzzword tail word
catch_phrase	Random company catch phrase
company_name	Random company name
company_suffix	Random company suffix
industry	Random industry
profession	Random profession

Credit card

Attribute	Description
credit_card_number	Random credit card number

Currency

Attribute	Description
currency_code	Random currency code
currency_name	Random currency name
currency_symbol	Random currency symbol

Filesystem

Attribute	Description
dir_path	Random directory path
file_extension	Random file extension
file_name	Random file name
file_path	Random file path
mime_type	Random MIME type
semver	Random semantic version
semver_stable	Random stable semver
semver_unstable	Random unstable semver

Finance

Attribute	Description
bic	Random BIC
isin	Random ISIN

Internet

Attribute	Description
domain_suffix	Random domain suffix
free_email	Random free email address
free_email_provider	Random free email provider
ip	Random IP address
ipv4	Random IPv4 address
ipv6	Random IPv6 address
mac_address	Random MAC address
password	Random password (8–20 chars)
safe_email	Random safe email address
user_agent	Random user agent string
username	Random username

Job

Attribute	Description
field	Random job field
position	Random job position
seniority	Random job seniority
job_title	Random job title

Name

Attribute	Description
first_name	Random first name
last_name	Random last name
name	Random full name
name_with_title	Random name with title
suffix	Random suffix
title	Random title

Number

Attribute	Description
digit	Random single digit

Phone number

Attribute	Description
cell_number	Random cell number
phone_number	Random phone number

Links

• Author: Martan03
• GitHub repository: faupi
• Author website: martan03.github.io