lib: handle throw undefined in assert.throws()

And make `assert.doesNotThrow()` handle it as well. Backport-PR-URL: #19230 PR-URL: #18029Fixes: #18027 Reviewed-By: Anna Henningsen <[email protected]> Reviewed-By: Ruben Bridgewater <[email protected]> Reviewed-By: Khaidi Chu <[email protected]> Reviewed-By: Tiancheng "Timothy" Gu <[email protected]> Reviewed-By: Daniel Bevenius <[email protected]> Reviewed-By: Colin Ihrig <[email protected]> Reviewed-By: James M Snell <[email protected]>

Author: bnoordhuis

lib/assert.js

@@ -31,6 +31,8 @@ const{inspect } = require('util');
 
 constassert=module.exports=ok;
 
+constNO_EXCEPTION_SENTINEL={};
+
 // All of the following functions must throw an AssertionError
 // when a corresponding condition is not met, with a message that
 // may be undefined if not provided. All assertion methods provide
@@ -256,6 +258,7 @@ function getActual(block){
 }catch(e){
 returne;
 }
+returnNO_EXCEPTION_SENTINEL;
 }
 
 // Expected to throw an error.
@@ -273,7 +276,7 @@ assert.throws = function throws(block, error, message){
 error=null;
 }
 
-if(actual===undefined){
+if(actual===NO_EXCEPTION_SENTINEL){
 letdetails='';
 if(error&&error.name){
 details+=` (${error.name})`;
@@ -294,7 +297,7 @@ assert.throws = function throws(block, error, message){
 
 assert.doesNotThrow=functiondoesNotThrow(block,error,message){
 constactual=getActual(block);
-if(actual===undefined)
+if(actual===NO_EXCEPTION_SENTINEL)
 return;
 
 if(typeoferror==='string'){
@@ -308,7 +311,7 @@ assert.doesNotThrow = function doesNotThrow(block, error, message){
  actual,
 expected: error,
 operator: 'doesNotThrow',
-message: `Got unwanted exception${details}\n${actual.message}`,
+message: `Got unwanted exception${details}\n${actual&&actual.message}`,
 stackStartFn: doesNotThrow
 });
 }

test/parallel/test-assert.js

@@ -857,4 +857,16 @@ common.expectsError(
 message: "message: expected '', not 'foo'"
 }
 );
+
+// eslint-disable-next-line no-throw-literal
+assert.throws(()=>{throwundefined;},/undefined/);
+common.expectsError(
+// eslint-disable-next-line no-throw-literal
+()=>assert.doesNotThrow(()=>{throwundefined;}),
+{
+type: assert.AssertionError,
+code: 'ERR_ASSERTION',
+message: 'Got unwanted exception.\nundefined'
+}
+);
 }