LOC-7325: make the LocalBinary Download tests actually run

The three Download tests could never pass. `binary.key` was never set,
though binaryPath() sets it before every real download() call, so the
source-url fetch was rejected with "Invalid auth token". `retries` was
omitted too, making the retry check `undefined > 0` — every failure went
straight to the terminal branch with no retry.

On master this block hangs rather than fails, because the terminal path
there never invokes the callback; that defect was fixed earlier in this
branch, which turned the hang into a fast assertion failure and made the
real cause visible.

With the key supplied the block passes for the first time, covering the
real HTTP download end to end — direct and through a proxy, async and
sync — which is what exercises the new non-200 response check against a
live source.

Verified with real credentials: full suite 59 passing, 1 failing. The one
failure (`should stop local`) fails identically on origin/master.

Author: vivianludrick

test/local.js

@@ -451,6 +451,10 @@ describe('LocalBinary', function () {
 
     beforeEach(function () {
       binary = new LocalBinary();
+      // binaryPath() normally sets this before calling download(); without it
+      // the source-url fetch is rejected with "Invalid auth token" and the
+      // download can never succeed, so these tests could not pass.
+      binary.key = process.env.BROWSERSTACK_ACCESS_KEY;
       tempDownloadPath = path.join(process.cwd(), 'download');
     });
 
@@ -465,7 +469,7 @@ describe('LocalBinary', function () {
         check(done, function(){
           expect(fs.existsSync(result)).to.equal(true);
         });
-      });
+      }, binary.baseRetries);
     });
 
     it('should download binaries with proxy', function (done) {
@@ -479,13 +483,13 @@ describe('LocalBinary', function () {
         check(done, function(){
           expect(fs.existsSync(result)).to.equal(true);
         });
-      });
+      }, binary.baseRetries);
     });
 
     it('should download binaries in sync', function () {
       this.timeout(MAX_TIMEOUT);
       var conf = {};
-      const result = binary.downloadSync(conf, tempDownloadPath);
+      const result = binary.downloadSync(conf, tempDownloadPath, binary.baseRetries);
       expect(fs.existsSync(result)).to.equal(true);
     });
   });