Bug 1571791 - "Step in" across an await expression jumps to unexpected places. r=loganfsmyth

Differential Revision: https://phabricator.services.mozilla.com/D42723

--HG--
extra : moz-landing-system : lando

devtools/server/actors/thread.js

@@ -834,6 +834,7 @@ const ThreadActor = ActorClassWithSpec(threadSpec, {
       if (completion.await || completion.yield) {
         thread.suspendedFrame = this;
         this.waitingOnStep = true;
+        thread.dbg.onEnterFrame = undefined;
         return undefined;
       }
 

devtools/server/tests/unit/test_stepping-14.js

@@ -0,0 +1,55 @@
+/* Any copyright is dedicated to the Public Domain.
+   http://creativecommons.org/publicdomain/zero/1.0/ */
+
+"use strict";
+
+/*
+ * Check that is possible to step into both the inner and outer function
+ * calls.
+ */
+
+add_task(
+  threadFrontTest(async ({ threadFront, targetFront, debuggee }) => {
+    dumpn("Evaluating test code and waiting for first debugger statement");
+
+    const consoleFront = await targetFront.getFront("console");
+    consoleFront.evaluateJSAsync(
+      `(function () {
+        async function f() {
+          const p = Promise.resolve(43);
+          await p;
+          return p;
+        }
+
+        function call_f() {
+          Promise.resolve(42).then(forty_two => {
+            return forty_two;
+          });
+
+          f().then(v => {
+            return v;
+          });
+        }
+        debugger;
+        call_f();
+      })()`
+    );
+
+    const packet = await waitForEvent(threadFront, "paused");
+    const location = {
+      sourceId: packet.frame.where.actor,
+      line: 4,
+      column: 10,
+    };
+
+    await threadFront.setBreakpoint(location, {});
+
+    const packet2 = await resumeAndWaitForPause(threadFront);
+    Assert.equal(packet2.frame.where.line, 4, "landed at await");
+
+    const packet3 = await stepIn(threadFront);
+    Assert.equal(packet3.frame.where.line, 5, "step to the next line");
+
+    await threadFront.resume();
+  })
+);

devtools/server/tests/unit/xpcshell.ini

@@ -195,6 +195,7 @@ skip-if = true # breakpoint sliding is not supported bug 1525685
 [test_stepping-11.js]
 [test_stepping-12.js]
 [test_stepping-13.js]
+[test_stepping-14.js]
 [test_stepping-with-skip-breakpoints.js]
 [test_framebindings-01.js]
 [test_framebindings-02.js]