Merge pull request #1765 from endojs/markm-tolerate-hide-extra-args

fix(exo)!: extra undeclared args dropped
endojs · Sep 18, 2023 · 9ef7e38 · 9ef7e38
2 parents 25c44ba + 9de852b
commit 9ef7e38
Show file tree

Hide file tree

Showing 2 changed files with 44 additions and 10 deletions.
diff --git a/packages/exo/src/exo-tools.js b/packages/exo/src/exo-tools.js
@@ -32,14 +32,31 @@ const { defineProperties, fromEntries } = Object;
  */
 const MinMethodGuard = M.call().rest(M.any()).returns(M.any());
 
-const defendSyncArgs = (args, methodGuardPayload, label) => {
+/**
+ * @param {Passable[]} syncArgs
+ * @param {MethodGuardPayload} methodGuardPayload
+ * @param {string} [label]
+ * @returns {Passable[]} Returns the args that should be passed to the
+ * raw method
+ */
+const defendSyncArgs = (syncArgs, methodGuardPayload, label = undefined) => {
   const { argGuards, optionalArgGuards, restArgGuard } = methodGuardPayload;
   const paramsPattern = M.splitArray(
     argGuards,
     optionalArgGuards,
     restArgGuard,
   );
-  mustMatch(harden(args), paramsPattern, label);
+  mustMatch(harden(syncArgs), paramsPattern, label);
+  if (restArgGuard !== undefined) {
+    return syncArgs;
+  }
+  const declaredLen =
+    argGuards.length + (optionalArgGuards ? optionalArgGuards.length : 0);
+  if (syncArgs.length <= declaredLen) {
+    return syncArgs;
+  }
+  // Ignore extraneous arguments, as a JS function call would do.
+  return syncArgs.slice(0, declaredLen);
 };
 
 /**
@@ -52,9 +69,13 @@ const defendSyncMethod = (method, methodGuardPayload, label) => {
   const { returnGuard } = methodGuardPayload;
   const { syncMethod } = {
     // Note purposeful use of `this` and concise method syntax
-    syncMethod(...args) {
-      defendSyncArgs(harden(args), methodGuardPayload, label);
-      const result = apply(method, this, args);
+    syncMethod(...syncArgs) {
+      const realArgs = defendSyncArgs(
+        harden(syncArgs),
+        methodGuardPayload,
+        label,
+      );
+      const result = apply(method, this, realArgs);
       mustMatch(harden(result), returnGuard, `${label}: result`);
       return result;
     },
@@ -83,9 +104,9 @@ const desync = methodGuardPayload => {
   return {
     awaitIndexes,
     rawMethodGuardPayload: {
+      ...methodGuardPayload,
       argGuards: rawArgGuards.slice(0, argGuards.length),
       optionalArgGuards: rawArgGuards.slice(argGuards.length),
-      restArgGuard,
     },
   };
 };
@@ -98,13 +119,13 @@ const defendAsyncMethod = (method, methodGuardPayload, label) => {
     asyncMethod(...args) {
       const awaitList = awaitIndexes.map(i => args[i]);
       const p = Promise.all(awaitList);
-      const rawArgs = [...args];
+      const syncArgs = [...args];
       const resultP = E.when(p, awaitedArgs => {
         for (let j = 0; j < awaitIndexes.length; j += 1) {
-          rawArgs[awaitIndexes[j]] = awaitedArgs[j];
+          syncArgs[awaitIndexes[j]] = awaitedArgs[j];
         }
-        defendSyncArgs(rawArgs, rawMethodGuardPayload, label);
-        return apply(method, this, rawArgs);
+        const realArgs = defendSyncArgs(syncArgs, rawMethodGuardPayload, label);
+        return apply(method, this, realArgs);
       });
       return E.when(resultP, result => {
         mustMatch(harden(result), returnGuard, `${label}: result`);

diff --git a/packages/exo/test/test-heap-classes.js b/packages/exo/test/test-heap-classes.js
@@ -10,6 +10,19 @@ import {
 } from '../src/exo-makers.js';
 import { GET_INTERFACE_GUARD } from '../src/exo-tools.js';
 
+const NoExtraI = M.interface('NoExtra', {
+  foo: M.call().returns(),
+});
+
+test('what happens with extra arguments', t => {
+  const exo = makeExo('WithExtra', NoExtraI, {
+    foo(x) {
+      t.is(x, undefined);
+    },
+  });
+  exo.foo('an extra arg');
+});
+
 const UpCounterI = M.interface('UpCounter', {
   incr: M.call()
     // TODO M.number() should not be needed to get a better error message