From 2228f6787cde3096273ae9d5f5da7e1cc8720fea Mon Sep 17 00:00:00 2001
From: Kevin Schaaf <kschaaf@google.com>
Date: Thu, 14 Mar 2019 15:45:53 -0700
Subject: [PATCH] Sync with fixes on master branch.

---
 lib/utils/debounce.html |   9 ++--
 test/unit/debounce.html | 117 +++++++++++++++++++++++++++-------------
 2 files changed, 85 insertions(+), 41 deletions(-)

diff --git a/lib/utils/debounce.html b/lib/utils/debounce.html
index 5b9e4d2a82..5290285e3b 100644
--- a/lib/utils/debounce.html
+++ b/lib/utils/debounce.html
@@ -39,8 +39,8 @@
       this._callback = callback;
       this._timer = this._asyncModule.run(() => {
         this._timer = null;
-        this._callback();
         debouncerQueue.delete(this);
+        this._callback();
       });
     }
     /**
@@ -51,7 +51,6 @@
     cancel() {
       if (this.isActive()) {
         this._cancelAsync();
-        this._timer = null;
         // Canceling a debouncer removes its spot from the flush queue,
         // so if a debouncer is manually canceled and re-debounced, it
         // will reset its flush order (this is a very minor difference from 1.x)
@@ -65,7 +64,10 @@
      * @return {void}
      */
     _cancelAsync() {
-      this._asyncModule.cancel(/** @type {number} */(this._timer));
+      if (this.isActive()) {
+        this._asyncModule.cancel(/** @type {number} */(this._timer));
+        this._timer = null;
+      }
     }
     /**
      * Flushes an active debouncer and returns a reference to itself.
@@ -158,7 +160,6 @@
         });
       }
     });
-    debouncerQueue = new Set();
     return didFlush;
   };
 
diff --git a/test/unit/debounce.html b/test/unit/debounce.html
index b380a62185..c9fb0195ea 100644
--- a/test/unit/debounce.html
+++ b/test/unit/debounce.html
@@ -34,6 +34,86 @@
     Polymer({is: 'x-basic'});
   });
 
+  suite('enqueueDebouncer & flush', function() {
+  
+    // NOTE: This is a regression test; the bug it fixed only occurred if the
+    // debouncer was flushed before any microtasks run, hence it should be
+    // first in this file
+    test('re-enqueue canceled debouncer', function() {
+      const cb = sinon.spy();
+      let db;
+      db = Polymer.Debouncer.debounce(null, Polymer.Async.microTask, cb);
+      Polymer.enqueueDebouncer(db);
+      db.cancel();
+      assert.equal(db.isActive(), false);
+      assert.equal(cb.callCount, 0);
+      db = Polymer.Debouncer.debounce(db, Polymer.Async.microTask, cb);
+      Polymer.enqueueDebouncer(db);
+      Polymer.flush();
+      assert.isTrue(cb.calledOnce);
+    });
+  
+    test('flushDebouncers from enqueued debouncer', function(done) {
+      const cb = sinon.spy(() => Polymer.flush());
+      let db = Polymer.Debouncer.debounce(null, Polymer.Async.microTask, cb);
+      Polymer.enqueueDebouncer(db);
+      setTimeout(() => {
+        assert.isTrue(cb.calledOnce);
+        done();
+      });
+    });
+  
+    const testEnqueue = (shouldFlush, done) => {
+      const actualOrder = [];
+      const enqueue = (type, {db, cb} = {}) => {
+        cb = cb || (() => actualOrder.push(cb));
+        db = Polymer.Debouncer.debounce(db, type, cb);
+        Polymer.enqueueDebouncer(db);
+        return {db, cb};
+      };
+      const db1 = enqueue(Polymer.Async.microTask);
+      const db2 = enqueue(Polymer.Async.microTask);
+      const db3 = enqueue(Polymer.Async.timeOut);
+      const db4 = enqueue(Polymer.Async.microTask);
+      enqueue(Polymer.Async.microTask, db2);
+      enqueue(Polymer.Async.microTask, db1);
+      if (shouldFlush) {
+        Polymer.flush();
+        assert.deepEqual(actualOrder, [db1.cb, db2.cb, db3.cb, db4.cb]);
+        done();
+      } else {
+        Polymer.Async.timeOut.run(() => {
+          assert.deepEqual(actualOrder, [db4.cb, db2.cb, db1.cb, db3.cb]);
+          done();
+        });
+      }
+    };
+  
+    test('non-flushed', function(done) {
+      testEnqueue(false, done);
+    });
+  
+    test('flushed', function(done) {
+      testEnqueue(true, done);
+    });
+  
+    test('reentrant flush', function() {
+      const cb2 = sinon.spy();
+      let db2;
+      const cb1 = sinon.spy(() => {
+        Polymer.flush();
+        db2 = Polymer.Debouncer.debounce(null, Polymer.Async.microTask, cb2);
+        Polymer.enqueueDebouncer(db2);
+      });
+      const db1 = Polymer.Debouncer.debounce(null, Polymer.Async.microTask, cb1);
+      Polymer.enqueueDebouncer(db1);
+      Polymer.flush();
+      assert.isTrue(cb1.calledOnce);
+      assert.isTrue(cb2.calledOnce);
+    });
+  
+  });
+
   suite('debounce', function() {
     var element;
 
@@ -208,43 +288,6 @@
       });
 
     });
-  });
-
-  suite('enqueueDebouncer & flush', function() {
-
-    const testEnqueue = (shouldFlush, done) => {
-      const actualOrder = [];
-      const enqueue = (type, {db, cb} = {}) => {
-        cb = cb || (() => actualOrder.push(cb));
-        db = Polymer.Debouncer.debounce(db, type, cb);
-        Polymer.enqueueDebouncer(db);
-        return {db, cb};
-      };
-      const db1 = enqueue(Polymer.Async.microTask);
-      const db2 = enqueue(Polymer.Async.microTask);
-      const db3 = enqueue(Polymer.Async.timeOut);
-      const db4 = enqueue(Polymer.Async.microTask);
-      enqueue(Polymer.Async.microTask, db2);
-      enqueue(Polymer.Async.microTask, db1);
-      if (shouldFlush) {
-        Polymer.flush();
-        assert.deepEqual(actualOrder, [db1.cb, db2.cb, db3.cb, db4.cb]);
-        done();
-      } else {
-        Polymer.Async.timeOut.run(() => {
-          assert.deepEqual(actualOrder, [db4.cb, db2.cb, db1.cb, db3.cb]);
-          done();
-        });
-      }
-    };
-
-    test('non-flushed', function(done) {
-      testEnqueue(false, done);
-    });
-
-    test('flushed', function(done) {
-      testEnqueue(true, done);
-    });
 
   });
 </script>