Merge pull request #1 from Adaptavist/detect-missing-fn-invoke

Throw meaningful error if a missing or invalid function invocation is attempted

Author: jollytoad

deno.json

@@ -1,14 +1,14 @@
 {
   "name": "@adaptavist/forge-resolver",
-  "version": "0.0.4",
+  "version": "0.0.5",
   "license": "MIT",
   "tasks": {
     "ok": "deno fmt && deno lint && deno check && deno test && deno publish --dry-run --allow-dirty"
   },
   "imports": {
     "@standard-schema/spec": "jsr:@standard-schema/spec@^1.0.0",
     "@std/assert": "jsr:@std/assert@^1.0.13",
-    "@std/testing": "jsr:@std/testing@^1.0.13"
+    "@std/testing": "jsr:@std/testing@^1.0.14"
   },
   "exports": {
     ".": "./lib/mod.ts",

deno.lock

@@ -1,4 +1,8 @@
+import type { ResolverFunction } from "@adaptavist/forge-resolver/types";
+
 export * from "./resolver/hello.ts";
 export * from "./resolver/helloValidated.ts";
 export * from "./resolver/another.ts";
 export * from "./resolver/nopayload.ts";
+
+export const notReallyAFunction = 123 as unknown as ResolverFunction;

lib/_fixtures/functions.ts

@@ -22,6 +22,7 @@ export function mockBridge(
         context,
       });
     } catch (e: unknown) {
+      console.error("Mock Bridge Error:", e);
       bridgeErrors.push(e);
       // TODO: what should we return on error?
     }

lib/mock-bridge.ts

@@ -171,6 +171,28 @@ Deno.test("invalid payload validation", async () => {
   const error = bridgeErrors.pop();
 
   assertIsError(error, SchemaError);
+});
+
+Deno.test("non-existent resolver function", async () => {
+  await invoke("nonExistentFunction", {});
+
+  const error = bridgeErrors.pop();
 
-  // console.log(error);
+  assertIsError(
+    error,
+    TypeError,
+    /^Resolver function not found: "nonExistentFunction"/,
+  );
+});
+
+Deno.test("invalid resolver function", async () => {
+  await invoke("notReallyAFunction", {});
+
+  const error = bridgeErrors.pop();
+
+  assertIsError(
+    error,
+    TypeError,
+    /^Resolver member is not a function: "notReallyAFunction"/,
+  );
 });

lib/resolver.test.ts

@@ -23,6 +23,19 @@ export function createResolver(fns: ResolverFunctionsModule): ResolverHandler {
   ) => {
     const fn = fns[functionKey];
 
+    if (!fn) {
+      throw new TypeError(
+        `Resolver function not found: "${functionKey}"\n` +
+          `Available functions: ${Object.keys(fns).join(", ")}`,
+      );
+    }
+
+    if (typeof fn !== "function") {
+      throw new TypeError(
+        `Resolver member is not a function: "${functionKey}"`,
+      );
+    }
+
     const schemas = getSchemas(fn);
 
     if (schemas) {

lib/resolver.ts

@@ -28,7 +28,7 @@ export function setSchemas<I extends AnyPayload, O extends AnyResult>(
 export function getSchemas<F extends ResolverFunction>(
   fn: F,
 ): Schemas | undefined {
-  return (fn as unknown as WithSchemas)[schemasSymbol];
+  return (fn as unknown as WithSchemas)?.[schemasSymbol];
 }
 
 export interface Schemas<