perf: Fix OOM issues caused by group-issues

Group issues mechanism was extending the "from" and "name" arrays in
the current vuln it was iterating on, and only then assigning it to
acc[vuln.id]. This meant that for every vulns that needs to be grouped,
an array larger by 1 (of "from" and of "name") is added to the vuln.
In large vulns results this may cause may OOM issues,
because of data duplication.
This fix changes the the mechanism so that when acc[vuln.id] exists,
it adds the current vuln's 'from' and 'name' values to the existing
acc[vuln.id].from and name arrays.

src/lib/formatters/test/format-test-results.ts

@@ -45,17 +45,26 @@ function createJsonResultOutput(jsonResult, options: Options) {
 
 function formatJsonVulnerabilityStructure(jsonResult, options: Options) {
   if (options['group-issues']) {
+    // Note: we have to reverse the array to keep the existing behavior so that the json output will stay the same.
+    // Since the entire array is reversed before grouping, we reverse it back after grouping to preserve the grouped vulns order.
+    const reversedVulnerabilities = jsonResult.vulnerabilities
+      ? jsonResult.vulnerabilities.slice().reverse()
+      : [];
     jsonResult.vulnerabilities = Object.values(
-      (jsonResult.vulnerabilities || []).reduce((acc, vuln): Record<
-        string,
-        any
-      > => {
-        vuln.from = [vuln.from].concat(acc[vuln.id]?.from || []);
-        vuln.name = [vuln.name].concat(acc[vuln.id]?.name || []);
-        acc[vuln.id] = vuln;
+      reversedVulnerabilities.reduce((acc, vuln): Record<string, any> => {
+        if (!acc[vuln.id]) {
+          acc[vuln.id] = {
+            ...vuln,
+            from: [vuln.from],
+            name: [vuln.name],
+          };
+        } else {
+          acc[vuln.id].from.push(vuln.from);
+          acc[vuln.id].name.push(vuln.name);
+        }
         return acc;
       }, {}),
-    );
+    ).reverse();
   }
 
   if (jsonResult.vulnerabilities) {