From f93cd3b1ba416acc0e877376eb7ff1fd549b5621 Mon Sep 17 00:00:00 2001
From: Kevin Ennis <kennis84@gmail.com>
Date: Thu, 23 Mar 2017 10:49:38 -0400
Subject: [PATCH] Fix error on call.toString() where stack has fewer than 4
 lines.

Fixes #1066
---
 lib/sinon/call.js |  2 +-
 test/call-test.js | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/lib/sinon/call.js b/lib/sinon/call.js
index 38bf8076c..9d8a2aab4 100644
--- a/lib/sinon/call.js
+++ b/lib/sinon/call.js
@@ -176,7 +176,7 @@ var callProto = {
         }
         if (this.stack) {
             // Omit the error message and the two top stack frames in sinon itself:
-            callStr += this.stack.split("\n")[3].replace(/^\s*(?:at\s+|@)?/, " at ");
+            callStr += ( this.stack.split("\n")[3] || "unknown" ).replace(/^\s*(?:at\s+|@)?/, " at ");
         }
 
         return callStr;
diff --git a/test/call-test.js b/test/call-test.js
index 3a080a20d..31b919a4f 100644
--- a/test/call-test.js
+++ b/test/call-test.js
@@ -835,6 +835,23 @@ describe("sinonSpy.call", function () {
 
             assert.equals(object.doIt.getCall(0).toString().replace(/ at.*/g, ""), "doIt() => 42");
         });
+
+        // https://github.com/sinonjs/sinon/issues/1066
+        it("does not throw when the call stack is empty", function (done) {
+            var stub1 = sinonStub().resolves(1);
+            var stub2 = sinonStub().returns(1);
+
+            function run() {
+                return stub1().then(stub2);
+            }
+
+            run()
+            .then(function () {
+                assert.equals(stub2.getCall(0).toString().replace(/ at.*/g, ""), "stub(1) => 1");
+                done();
+            })
+            .catch( done );
+        });
     });
 
     describe("constructor", function () {