Build system: improve build for development workflow

This adds a "test-only" gulp task that runs only tests (without clean/lint) and makes the single-spec test environment consistent with the whole-suite case.

gulpfile.js

@@ -389,7 +389,8 @@ gulp.task('build-bundle-dev', gulp.series(makeDevpackPkg, gulpBundle.bind(null,
 gulp.task('build-bundle-prod', gulp.series(makeWebpackPkg, gulpBundle.bind(null, false)));
 
 // public tasks (dependencies are needed for each task since they can be ran on their own)
-gulp.task('test', gulp.series(clean, lint, test));
+gulp.task('test-only', test);
+gulp.task('test', gulp.series(clean, lint, 'test-only'));
 
 gulp.task('test-coverage', gulp.series(clean, testCoverage));
 gulp.task(viewCoverage);

karma.conf.maker.js

@@ -111,7 +111,7 @@ module.exports = function(codeCoverage, browserstack, watchMode, file) {
   var webpackConfig = newWebpackConfig(codeCoverage);
   var plugins = newPluginsArray(browserstack);
 
-  var files = file ? ['test/helpers/prebidGlobal.js', file] : ['test/test_index.js'];
+  var files = file ? ['test/test_deps.js', file] : ['test/test_index.js'];
   // This file opens the /debug.html tab automatically.
   // It has no real value unless you're running --watch, and intend to do some debugging in the browser.
   if (watchMode) {

test/helpers/prebidGlobal.js

@@ -1,3 +1,4 @@
 window.$$PREBID_GLOBAL$$ = (window.$$PREBID_GLOBAL$$ || {});
+window.$$PREBID_GLOBAL$$.installedModules = (window.$$PREBID_GLOBAL$$.installedModules || []);
 window.$$PREBID_GLOBAL$$.cmd = window.$$PREBID_GLOBAL$$.cmd || [];
 window.$$PREBID_GLOBAL$$.que = window.$$PREBID_GLOBAL$$.que || [];

test/test_deps.js

@@ -0,0 +1,3 @@
+require('test/helpers/prebidGlobal.js');
+require('test/mocks/adloaderStub.js');
+require('test/mocks/xhr.js');

test/test_index.js

@@ -1,6 +1,4 @@
-require('test/helpers/prebidGlobal.js');
-require('test/mocks/adloaderStub.js');
-require('test/mocks/xhr.js');
+require('./test_deps.js');
 
 var testsContext = require.context('.', true, /_spec$/);
 testsContext.keys().forEach(testsContext);