Go REST Client Library

A Go library for executing HTTP requests from .http files and validating responses. Write once, use everywhere - for both manual testing and automated E2E tests.

Why This Library?

Problem: I wanted to use the same .http files for both manual testing (JetBrains HTTP Client, VS Code REST Client) and automated E2E testing in Go. No existing library offered full compatibility with both environments.

Solution: This library parses .http files exactly like popular IDE extensions, enabling seamless workflow between manual and automated testing.

Key Features

• Full JetBrains/VS Code compatibility - Same .http syntax, variables, and behaviors
• Variable substitution - Custom variables, environment variables, system variables ({{$guid}}, {{$randomInt}}, etc.)
• Response validation - Compare responses against .hresp files with placeholders ({{$any}}, {{$regexp}}, {{$anyGuid}})
• Multiple requests per file - Separated by ###
• E2E testing ready - Perfect for automated integration tests

Installation

go get github.com/bmcszk/go-restclient

Quick Start

1. Create a .http file

@baseUrl = https://api.example.com
@userId = 123

### Get user profile
GET {{baseUrl}}/users/{{userId}}
Authorization: Bearer {{authToken}}
X-Request-ID: {{$guid}}

### Create new user  
POST {{baseUrl}}/users
Content-Type: application/json

{
  "id": "{{$randomInt 1000 9999}}",
  "name": "Test User",
  "createdAt": "{{$timestamp}}"
}

2. Execute in Go

package main

import (
    "context"
    "log"
    "github.com/bmcszk/go-restclient"
)

func main() {
    client, err := restclient.NewClient(
        restclient.WithVars(map[string]interface{}{
            "authToken": "your-token-here",
        }),
    )
    if err != nil {
        log.Fatal(err)
    }

    responses, err := client.ExecuteFile(context.Background(), "requests.http")
    if err != nil {
        log.Fatal(err)
    }

    for i, resp := range responses {
        if resp.Error != nil {
            log.Printf("Request %d failed: %v", i+1, resp.Error)
        } else {
            log.Printf("Request %d: %d %s", i+1, resp.StatusCode, resp.Status)
        }
    }
}

Variable Types

Custom Variables

@baseUrl = https://api.example.com
@userId = 123

GET {{baseUrl}}/users/{{userId}}

System Variables

• {{$guid}} - UUID (e.g., 123e4567-e89b-12d3-a456-426614174000)
• {{$randomInt}} or {{$randomInt 1 100}} - Random integer
• {{$timestamp}} - Unix timestamp
• {{$datetime}} or {{$datetime "2006-01-02"}} - Current datetime
• {{$processEnv VAR_NAME}} - Environment variable
• {{$dotenv VAR_NAME}} - From .env file

JetBrains Faker Variables

• {{$randomFirstName}}, {{$randomLastName}}
• {{$randomPhoneNumber}}, {{$randomStreetAddress}}
• {{$randomUrl}}, {{$randomUserAgent}}

Programmatic Variables (highest precedence)

client, err := restclient.NewClient(
    restclient.WithVars(map[string]interface{}{
        "userId": "override-value",
        "authToken": "secret-token",
    }),
)

Response Validation

Create .hresp files to validate responses:

responses.hresp:

HTTP/1.1 200 OK
Content-Type: application/json

{
  "id": "{{$anyGuid}}",
  "name": "{{$any}}",
  "createdAt": "{{$anyTimestamp}}"
}

###

HTTP/1.1 201 Created
Content-Type: application/json

{
  "id": "{{$regexp `\d{4}`}}",
  "status": "created"
}

Validate in Go:

err := client.ValidateResponses("responses.hresp", responses...)
if err != nil {
    log.Fatal("Validation failed:", err)
}

Validation Placeholders

• {{$any}} - Matches any text
• {{$regexp pattern}} - Regex pattern (in backticks)
• {{$anyGuid}} - UUID format
• {{$anyTimestamp}} - Unix timestamp
• {{$anyDatetime 'format'}} - Datetime (rfc1123, iso8601, or custom)

Client Options

client, err := restclient.NewClient(
    restclient.WithBaseURL("https://api.example.com"),
    restclient.WithDefaultHeader("X-API-Key", "secret"),
    restclient.WithHTTPClient(customHTTPClient),
    restclient.WithVars(variables),
)

Compatible Syntax

Works with files created for:

• JetBrains HTTP Client
• VS Code REST Client

📚 Complete HTTP Syntax Reference - Comprehensive documentation of all supported HTTP request syntax, variables, and features.

Use Cases

Manual Testing

Use your favorite IDE extension to test APIs during development.

Automated E2E Testing

func TestUserAPI(t *testing.T) {
    client, _ := restclient.NewClient(
        restclient.WithBaseURL(testServer.URL),
    )
    
    responses, err := client.ExecuteFile(context.Background(), "user_tests.http")
    require.NoError(t, err)
    
    err = client.ValidateResponses("user_expected.hresp", responses...)
    require.NoError(t, err)
}

CI/CD Integration

go test ./tests/e2e/... # Runs tests using .http files

Development

Prerequisites

• Go 1.21+

Commands

make check          # Run all checks (lint, test, build)
make test-unit      # Run unit tests only
go test .           # Quick test

Test Coverage

Current coverage: 78.4% (187 tests passing)

License

MIT License