assert: make assertion_error use Myers diff algorithm

Fixes: #51733
Co-Authored-By: Pietro Marchini <pietro.marchini94@gmail.com>
PR-URL: #54862
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>

Author: 2 people

lib/internal/assert/assertion_error.js

@@ -0,0 +1,167 @@
+'use strict';
+
+const{
+ Array,
+ ArrayPrototypeFill,
+ ArrayPrototypePush,
+ ArrayPrototypeSlice,
+ StringPrototypeEndsWith,
+}=primordials;
+
+constcolors=require('internal/util/colors');
+
+constkNopLinesToCollapse=5;
+
+functionareLinesEqual(actual,expected,checkCommaDisparity){
+if(actual===expected){
+returntrue;
+}
+if(checkCommaDisparity){
+return`${actual},`===expected||actual===`${expected},`;
+}
+returnfalse;
+}
+
+functionmyersDiff(actual,expected,checkCommaDisparity=false){
+constactualLength=actual.length;
+constexpectedLength=expected.length;
+constmax=actualLength+expectedLength;
+constv=ArrayPrototypeFill(Array(2*max+1),0);
+
+consttrace=[];
+
+for(letdiffLevel=0;diffLevel<=max;diffLevel++){
+constnewTrace=ArrayPrototypeSlice(v);
+ArrayPrototypePush(trace,newTrace);
+
+for(letdiagonalIndex=-diffLevel;diagonalIndex<=diffLevel;diagonalIndex+=2){
+letx;
+if(diagonalIndex===-diffLevel||
+(diagonalIndex!==diffLevel&&v[diagonalIndex-1+max]<v[diagonalIndex+1+max])){
+x=v[diagonalIndex+1+max];
+}else{
+x=v[diagonalIndex-1+max]+1;
+}
+
+lety=x-diagonalIndex;
+
+while(x<actualLength&&y<expectedLength&&areLinesEqual(actual[x],expected[y],checkCommaDisparity)){
+x++;
+y++;
+}
+
+v[diagonalIndex+max]=x;
+
+if(x>=actualLength&&y>=expectedLength){
+returnbacktrack(trace,actual,expected,checkCommaDisparity);
+}
+}
+}
+}
+
+functionbacktrack(trace,actual,expected,checkCommaDisparity){
+constactualLength=actual.length;
+constexpectedLength=expected.length;
+constmax=actualLength+expectedLength;
+
+letx=actualLength;
+lety=expectedLength;
+constresult=[];
+
+for(letdiffLevel=trace.length-1;diffLevel>=0;diffLevel--){
+constv=trace[diffLevel];
+constdiagonalIndex=x-y;
+letprevDiagonalIndex;
+
+if(diagonalIndex===-diffLevel||
+(diagonalIndex!==diffLevel&&v[diagonalIndex-1+max]<v[diagonalIndex+1+max])){
+prevDiagonalIndex=diagonalIndex+1;
+}else{
+prevDiagonalIndex=diagonalIndex-1;
+}
+
+constprevX=v[prevDiagonalIndex+max];
+constprevY=prevX-prevDiagonalIndex;
+
+while(x>prevX&&y>prevY){
+constvalue=!checkCommaDisparity||
+StringPrototypeEndsWith(actual[x-1],',') ? actual[x-1] : expected[y-1];
+ArrayPrototypePush(result,{__proto__: null,type: 'nop', value });
+x--;
+y--;
+}
+
+if(diffLevel>0){
+if(x>prevX){
+ArrayPrototypePush(result,{__proto__: null,type: 'insert',value: actual[x-1]});
+x--;
+}else{
+ArrayPrototypePush(result,{__proto__: null,type: 'delete',value: expected[y-1]});
+y--;
+}
+}
+}
+
+returnresult;
+}
+
+functionprintSimpleMyersDiff(diff){
+letmessage='';
+
+for(letdiffIdx=diff.length-1;diffIdx>=0;diffIdx--){
+const{ type, value }=diff[diffIdx];
+if(type==='insert'){
+message+=`${colors.green}${value}${colors.white}`;
+}elseif(type==='delete'){
+message+=`${colors.red}${value}${colors.white}`;
+}else{
+message+=`${colors.white}${value}${colors.white}`;
+}
+}
+
+return`\n${message}`;
+}
+
+functionprintMyersDiff(diff,simple=false){
+letmessage='';
+letskipped=false;
+letnopCount=0;
+
+for(letdiffIdx=diff.length-1;diffIdx>=0;diffIdx--){
+const{ type, value }=diff[diffIdx];
+constpreviousType=(diffIdx<(diff.length-1)) ? diff[diffIdx+1].type : null;
+consttypeChanged=previousType&&(type!==previousType);
+
+if(typeChanged&&previousType==='nop'){
+// Avoid grouping if only one line would have been grouped otherwise
+if(nopCount===kNopLinesToCollapse+1){
+message+=`${colors.white}${diff[diffIdx+1].value}\n`;
+}elseif(nopCount===kNopLinesToCollapse+2){
+message+=`${colors.white}${diff[diffIdx+2].value}\n`;
+message+=`${colors.white}${diff[diffIdx+1].value}\n`;
+}if(nopCount>=(kNopLinesToCollapse+3)){
+message+=`${colors.blue}...${colors.white}\n`;
+message+=`${colors.white}${diff[diffIdx+1].value}\n`;
+skipped=true;
+}
+nopCount=0;
+}
+
+if(type==='insert'){
+message+=`${colors.green}+${colors.white}${value}\n`;
+}elseif(type==='delete'){
+message+=`${colors.red}-${colors.white}${value}\n`;
+}elseif(type==='nop'){
+if(nopCount<kNopLinesToCollapse){
+message+=`${colors.white}${value}\n`;
+}
+nopCount++;
+}
+}
+
+message=message.trimEnd();
+
+return{message: `\n${message}`, skipped };
+}
+
+module.exports={ myersDiff, printMyersDiff, printSimpleMyersDiff };

lib/internal/assert/myers_diff.js

@@ -29,14 +29,20 @@ test('', { skip: !hasCrypto }, () => {
 ()=>assert.deepStrictEqual(date,fake),
 {
 message: 'Expected values to be strictly deep-equal:\n'+
-'+ actual - expected\n\n+ 2016-01-01T00:00:00.000Z\n- Date {}'
+'+ actual - expected\n'+
+'\n'+
+'+ 2016-01-01T00:00:00.000Z\n'+
+'- Date {}\n'
 }
 );
 assert.throws(
 ()=>assert.deepStrictEqual(fake,date),
 {
 message: 'Expected values to be strictly deep-equal:\n'+
-'+ actual - expected\n\n+ Date {}\n- 2016-01-01T00:00:00.000Z'
+'+ actual - expected\n'+
+'\n'+
+'+ Date {}\n'+
+'- 2016-01-01T00:00:00.000Z\n'
 }
 );
 }