HTTP and API Assertions¶

Axiom.Http is the optional Axiom package for practical HttpResponseMessage assertions.

It keeps the first wave focused on common API-test needs:

exact status-code assertions
header presence, absence, and exact-value assertions
focused content-type assertions
JSON body assertions that reuse Axiom.Json
minimal ProblemDetails assertions

Install¶

dotnet add package Axiom.Http

Use it alongside Axiom.Assertions:

using System.Net;
using System.Net.Http;
using System.Text;
using Axiom.Assertions;
using Axiom.Http;

Supported Subject¶

The first wave is intentionally centered on HttpResponseMessage.

using System.Net;
using System.Net.Http;
using Axiom.Http;

using var response = new HttpResponseMessage(HttpStatusCode.OK);

var assertions = response.Should();

Exact Status Codes¶

Exact status-code assertions are the primary shape for this package.

using System.Net;
using System.Net.Http;
using System.Text;
using Axiom.Http;

using var response = new HttpResponseMessage(HttpStatusCode.Created)
{
    Content = new StringContent("{}", Encoding.UTF8, "application/json")
};

response.Should().HaveStatusCode(HttpStatusCode.Created);
response.Should().HaveStatusCode(201);
response.Should().NotHaveStatusCode(HttpStatusCode.BadRequest);
response.Should().NotHaveStatusCode(404);

Headers and Content Type¶

Header lookup checks both response headers and content headers.

HaveHeaderValue(...) expects exactly one header value. HaveHeaderValues(...) checks exact count and exact order.

using System.Net;
using System.Net.Http;
using System.Text;
using Axiom.Http;

using var response = new HttpResponseMessage(HttpStatusCode.OK)
{
    Content = new StringContent("{\"id\":1}", Encoding.UTF8, "application/json")
};

response.Headers.Add("ETag", "\"v1\"");
response.Headers.Add("X-Trace", ["a", "b"]);

response.Should().HaveHeader("ETag");
response.Should().NotHaveHeader("Retry-After");
response.Should().HaveHeaderValue("ETag", "\"v1\"");
response.Should().HaveHeaderValues("X-Trace", ["a", "b"]);
response.Should().HaveContentType("application/json");
response.Should().HaveContentTypeWithCharset("application/json", "utf-8");

JSON Response Bodies¶

JSON body assertions use Axiom.Json.

This means JSON body equivalency and JSON path behavior stay aligned with the JSON package:

object property order does not matter
array order does matter
numeric comparison uses normalized JSON numeric values

using System.Net;
using System.Net.Http;
using System.Text;
using Axiom.Http;

using var response = new HttpResponseMessage(HttpStatusCode.OK)
{
    Content = new StringContent(
        """
        { "id": 1, "name": "Ada", "roles": ["admin", "author"] }
        """,
        Encoding.UTF8,
        "application/json")
};

var expectedJson = """
    { "roles": ["admin", "author"], "name": "Ada", "id": 1.0 }
    """;

response.Should().HaveJsonBodyEquivalentTo(expectedJson);
response.Should().HaveJsonPath("$.roles[1]");
response.Should().HaveJsonStringAtPath("$.name", "Ada");
response.Should().HaveJsonNumberAtPath("$.id", 1m);

If you want JSON assertions over raw JSON strings, JsonDocument, or JsonElement directly, use JSON.

ProblemDetails¶

The first wave includes small, direct ProblemDetails assertions for common error-response checks.

These assertions expect a response body with application/problem+json.

using System.Net;
using System.Net.Http;
using System.Text;
using Axiom.Http;

using var response = new HttpResponseMessage(HttpStatusCode.BadRequest)
{
    Content = new StringContent(
        """
        {
          "type": "https://example.test/problems/validation",
          "title": "Validation failed",
          "status": 400,
          "detail": "Name is required."
        }
        """,
        Encoding.UTF8,
        "application/problem+json")
};

response.Should().HaveProblemDetails();
response.Should().HaveProblemDetailsTitle("Validation failed");
response.Should().HaveProblemDetailsStatus(400);
response.Should().HaveProblemDetailsType("https://example.test/problems/validation");
response.Should().HaveProblemDetailsDetail("Name is required.");

First-Wave Limits¶

Axiom.Http is intentionally narrow in its first release:

HttpResponseMessage only
no ASP.NET-specific result helpers
no test-server helpers
no category-level status-code assertions
no snapshot features
no full API-client helper layer

For the full method list, see the Assertion Reference.