Add better status messages

Author: ejsmith

mod.ts

@@ -2,6 +2,7 @@ export { FetchClient } from "./src/FetchClient.ts";
 export type { FetchClientOptions } from "./src/FetchClientOptions.ts";
 export type { FetchClientResponse } from "./src/FetchClientResponse.ts";
 export { FetchClientError } from "./src/FetchClientError.ts";
+export { getStatusText } from "./src/HttpStatusText.ts";
 export { ResponsePromise } from "./src/ResponsePromise.ts";
 export { ProblemDetails } from "./src/ProblemDetails.ts";
 export {

src/FetchClient.ts

@@ -12,6 +12,7 @@ import type { FetchClientOptions } from "./FetchClientOptions.ts";
 import { type IObjectEvent, ObjectEvent } from "./ObjectEvent.ts";
 import { ResponsePromise } from "./ResponsePromise.ts";
 import { FetchClientError } from "./FetchClientError.ts";
+import { getStatusText } from "./HttpStatusText.ts";
 
 type Fetch = typeof globalThis.fetch;
 type RequestInitWithObjectBody = Omit<RequestInit, "body"> & {
@@ -729,7 +730,7 @@ export class FetchClient {
     return {
       url,
       status: problem.status ?? 422,
-      statusText: problem.title ?? "Unprocessable Entity",
+      statusText: problem.title ?? getStatusText(problem.status ?? 422),
       body: null,
       bodyUsed: true,
       ok: false,
@@ -835,7 +836,9 @@ export class FetchClient {
 
     response.problem ??= new ProblemDetails();
     response.problem.status = response.status;
-    response.problem.title = `Unexpected status code: ${response.status}`;
+    if (!response.problem.title) {
+      response.problem.title = getStatusText(response.status);
+    }
     response.problem.setErrorMessage(response.problem.title);
 
     throw new FetchClientError(response);

src/FetchClientError.ts

@@ -1,4 +1,5 @@
 import type { FetchClientResponse } from "./FetchClientResponse.ts";
+import { getStatusText } from "./HttpStatusText.ts";
 
 /**
  * Error wrapper for non-2xx responses.
@@ -14,7 +15,7 @@ export class FetchClientError extends Error {
     super(
       message ??
         response.problem?.title ??
-        `Unexpected status code: ${response.status}`,
+        getStatusText(response.status),
     );
     this.name = "FetchClientError";
     this.response = response;

src/HttpStatusText.ts

@@ -0,0 +1,50 @@
+const STATUS_TEXT: Record<number, string> = {
+  400: "Bad Request",
+  401: "Unauthorized",
+  402: "Payment Required",
+  403: "Forbidden",
+  404: "Not Found",
+  405: "Method Not Allowed",
+  406: "Not Acceptable",
+  407: "Proxy Authentication Required",
+  408: "Request Timeout",
+  409: "Conflict",
+  410: "Gone",
+  411: "Length Required",
+  412: "Precondition Failed",
+  413: "Content Too Large",
+  414: "URI Too Long",
+  415: "Unsupported Media Type",
+  416: "Range Not Satisfiable",
+  417: "Expectation Failed",
+  418: "I'm a Teapot",
+  421: "Misdirected Request",
+  422: "Unprocessable Entity",
+  423: "Locked",
+  424: "Failed Dependency",
+  425: "Too Early",
+  426: "Upgrade Required",
+  428: "Precondition Required",
+  429: "Too Many Requests",
+  431: "Request Header Fields Too Large",
+  451: "Unavailable For Legal Reasons",
+  500: "Internal Server Error",
+  501: "Not Implemented",
+  502: "Bad Gateway",
+  503: "Service Unavailable",
+  504: "Gateway Timeout",
+  505: "HTTP Version Not Supported",
+  506: "Variant Also Negotiates",
+  507: "Insufficient Storage",
+  508: "Loop Detected",
+  510: "Not Extended",
+  511: "Network Authentication Required",
+};
+
+/**
+ * Returns the standard HTTP reason phrase for a status code,
+ * or `"Unknown Status Code"` if the code is not recognized.
+ */
+export function getStatusText(status: number): string {
+  return STATUS_TEXT[status] ?? "Unknown Status Code";
+}

src/tests/ErrorHandling.test.ts

@@ -148,12 +148,12 @@ Deno.test("handles 400 response with non-JSON text", async () => {
     assert(response.problem);
     assert(response.problem.errors);
     assert(response.problem.title);
-    assertStringIncludes(response.problem.title, "Unexpected status");
+    assertStringIncludes(response.problem.title, "Bad Request");
     assert(response.problem.errors.general);
     assertEquals(response.problem.errors.general.length, 1);
     assertStringIncludes(
       response.problem.errors.general[0],
-      "Unexpected status",
+      "Bad Request",
     );
   }
 

src/tests/RateLimit.test.ts

@@ -198,7 +198,7 @@ Deno.test("RateLimitMiddleware - returns 429 response when configured", async ()
     const response = (error as { response: FetchClientResponse<unknown> })
       .response;
     assertEquals(response.status, 429);
-    assertEquals(response.problem?.title, "Unexpected status code: 429");
+    assertEquals(response.problem?.title, "Too Many Requests");
     if (response.problem?.detail) {
       assertEquals(
         response.problem.detail.includes("Custom rate limit message"),