http2: fix closedCode NaN, increase test coverage

[kFinish](code) can be triggered from a 'finish' event (for example
when calling response.end) which does not pass code. That tries to
set closedCode to undefined resulting in NaN closedCode instead of
NGHTTP2_NO_ERROR. Check for code !== undefined before setting.
Adds tests for closed and closedCode.

PR-URL: #15154
Reviewed-By: Timothy Gu <timothygu99@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>

lib/internal/http2/compat.js

@@ -249,7 +249,8 @@ class Http2ServerRequest extends Readable {
     const state = this[kState];
     if (state.closed)
       return;
-    state.closedCode = code;
+    if (code !== undefined)
+      state.closedCode = code;
     state.closed = true;
     this.push(null);
     this[kStream] = undefined;
@@ -522,7 +523,8 @@ class Http2ServerResponse extends Stream {
     const state = this[kState];
     if (state.closed)
       return;
-    state.closedCode = code;
+    if (code !== undefined)
+      state.closedCode = code;
     state.closed = true;
     this.end();
     this[kStream] = undefined;

test/parallel/test-http2-compat-serverrequest.js

@@ -21,6 +21,9 @@ server.listen(0, common.mustCall(function() {
       httpVersionMinor: 0
     };
 
+    assert.strictEqual(request.closed, false);
+    assert.strictEqual(request.code, h2.constants.NGHTTP2_NO_ERROR);
+
     assert.strictEqual(request.statusCode, expected.statusCode);
     assert.strictEqual(request.httpVersion, expected.version);
     assert.strictEqual(request.httpVersionMajor, expected.httpVersionMajor);
@@ -31,6 +34,8 @@ server.listen(0, common.mustCall(function() {
     assert.strictEqual(request.socket, request.connection);
 
     response.on('finish', common.mustCall(function() {
+      assert.strictEqual(request.closed, true);
+      assert.strictEqual(request.code, h2.constants.NGHTTP2_NO_ERROR);
       server.close();
     }));
     response.end();

test/parallel/test-http2-compat-serverresponse-headers.js

@@ -84,7 +84,10 @@ server.listen(0, common.mustCall(function() {
     response.sendDate = false;
     assert.strictEqual(response.sendDate, false);
 
+    assert.strictEqual(response.code, h2.constants.NGHTTP2_NO_ERROR);
+
     response.on('finish', common.mustCall(function() {
+      assert.strictEqual(response.code, h2.constants.NGHTTP2_NO_ERROR);
       server.close();
     }));
     response.end();