test: prepare tests for no-cond-assign ESLint rule

PR-URL: #41614
Reviewed-By: Tobias Nießen <tniessen@tnie.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>

test/parallel/test-child-process-flush-stdio.js

@@ -27,7 +27,7 @@ const spawnWithReadable = () => {
   }));
   p.stdout.on('readable', () => {
     let buf;
-    while (buf = p.stdout.read())
+    while ((buf = p.stdout.read()) !== null)
       buffer.push(buf);
   });
 };

test/parallel/test-net-server-max-connections.js

@@ -68,7 +68,7 @@ function makeConnection(index) {
       if (closes === N / 2) {
         let cb;
         console.error('calling wait callback.');
-        while (cb = waits.shift()) {
+        while ((cb = waits.shift()) !== undefined) {
           cb();
         }
         server.close();

test/parallel/test-stream-readable-object-multi-push-async.js

@@ -47,7 +47,7 @@ const BATCH = 10;
   readable.on('readable', () => {
     let data;
     console.log('readable emitted');
-    while (data = readable.read()) {
+    while ((data = readable.read()) !== null) {
       console.log(data);
     }
   });

test/parallel/test-stream-unshift-empty-chunk.js

@@ -41,7 +41,7 @@ let readAll = false;
 const seen = [];
 r.on('readable', () => {
   let chunk;
-  while (chunk = r.read()) {
+  while ((chunk = r.read()) !== null) {
     seen.push(chunk.toString());
     // Simulate only reading a certain amount of the data,
     // and then putting the rest of the chunk back into the

test/parallel/test-zlib-brotli-flush.js

@@ -16,7 +16,7 @@ deflater.write(chunk, function() {
   deflater.flush(function() {
     const bufs = [];
     let buf;
-    while (buf = deflater.read())
+    while ((buf = deflater.read()) !== null)
       bufs.push(buf);
     actualFull = Buffer.concat(bufs);
   });

test/parallel/test-zlib-flush.js

@@ -23,7 +23,7 @@ deflater.write(chunk, function() {
     deflater.flush(function() {
       const bufs = [];
       let buf;
-      while (buf = deflater.read())
+      while ((buf = deflater.read()) !== null)
         bufs.push(buf);
       actualFull = Buffer.concat(bufs);
     });

test/parallel/test-zlib-params.js

@@ -21,7 +21,7 @@ deflater.write(chunk1, function() {
     deflater.end(chunk2, function() {
       const bufs = [];
       let buf;
-      while (buf = deflater.read())
+      while ((buf = deflater.read()) !== null)
         bufs.push(buf);
       actual = Buffer.concat(bufs);
     });