test: refactor addons-napi/test_exception/test.js

* provide block scoping to prevent unintended side effects * remove confusing and unnecessary assertion message * use consisitent `actual, expected` argument order for assertions Backport-PR-URL: #19447 PR-URL: #18340 Reviewed-By: Colin Ihrig <cjihrig@gmail.com> Reviewed-By: Jon Moss <me@jonathanmoss.me> Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Trott

test/addons-napi/test_exception/test.js

@@ -4,49 +4,47 @@ const common = require('../../common');
 const test_exception = require(`./build/${common.buildType}/test_exception`);
 const assert = require('assert');
 const theError = new Error('Some error');
-function throwTheError() {
- throw theError;
+
+{
+ const throwTheError = () => { throw theError; };
+
+ // Test that the native side successfully captures the exception
+ let returnedError = test_exception.returnException(throwTheError);
+ assert.strictEqual(theError, returnedError);
+
+ // Test that the native side passes the exception through
+ assert.throws(
+ () => { test_exception.allowException(throwTheError); },
+ (err) => err === theError
+ );
+
+ // Test that the exception thrown above was marked as pending
+ // before it was handled on the JS side
+ assert.strictEqual(test_exception.wasPending(), true,
+ 'VM was marked as having an exception pending' +
+ ' when it was allowed through');
+
+ // Test that the native side does not capture a non-existing exception
+ returnedError = test_exception.returnException(common.mustCall());
+ assert.strictEqual(returnedError, undefined,
+ 'Returned error should be undefined when no exception is' +
+ ` thrown, but ${returnedError} was passed`);
 }
-let caughtError;
-
-// Test that the native side successfully captures the exception
-let returnedError = test_exception.returnException(throwTheError);
-assert.strictEqual(theError, returnedError);
-
-// Test that the native side passes the exception through
-assert.throws(
- () => {
- test_exception.allowException(throwTheError);
- },
- function(err) {
- return err === theError;
- },
- 'Thrown exception was allowed to pass through unhindered'
-);
-
-// Test that the exception thrown above was marked as pending
-// before it was handled on the JS side
-assert.strictEqual(test_exception.wasPending(), true,
- 'VM was marked as having an exception pending' +
- ' when it was allowed through');
-
-// Test that the native side does not capture a non-existing exception
-returnedError = test_exception.returnException(common.mustCall());
-assert.strictEqual(undefined, returnedError,
- 'Returned error should be undefined when no exception is' +
- ` thrown, but ${returnedError} was passed`);
-
-// Test that no exception appears that was not thrown by us
-try {
- test_exception.allowException(common.mustCall());
-} catch (anError) {
- caughtError = anError;
+
+{
+ // Test that no exception appears that was not thrown by us
+ let caughtError;
+ try {
+ test_exception.allowException(common.mustCall());
+ } catch (anError) {
+ caughtError = anError;
+ }
+ assert.strictEqual(caughtError, undefined,
+ 'No exception originated on the native side, but' +
+ ` ${caughtError} was passed`);
+
+ // Test that the exception state remains clear when no exception is thrown
+ assert.strictEqual(test_exception.wasPending(), false,
+ 'VM was not marked as having an exception pending' +
+ ' when none was allowed through');
 }
-assert.strictEqual(undefined, caughtError,
- 'No exception originated on the native side, but' +
- ` ${caughtError} was passed`);
-
-// Test that the exception state remains clear when no exception is thrown
-assert.strictEqual(test_exception.wasPending(), false,
- 'VM was not marked as having an exception pending' +
- ' when none was allowed through');