Add Console wrapper to introduce logging level to console for unit tests

test/unit/three.source.unit.js

@@ -1,3 +1,4 @@
+import './utils/console-wrapper.js';
 import './utils/qunit-utils.js';
 
 //src

test/unit/utils/console-wrapper.js

@@ -0,0 +1,52 @@
+// This easy console wrapper introduces the logging level to console for
+// preventing console outputs caused when we purposely test the code path
+// including console outputs.
+//
+// Example: Prevent the console warnings caused by Color.setStyle().
+//   const c = new Color();
+//   console.level = CONSOLE_LEVEL.ERROR;
+//   c.setStyle( 'rgba(255,0,0,0.5)' );
+//   console.level = CONSOLE_LEVEL.DEFAULT;
+//
+// See https://github.com/mrdoob/three.js/issues/20760#issuecomment-735190998
+
+export const CONSOLE_LEVEL = {
+	OFF : 0,
+    ERROR : 1,
+    WARN : 2,
+    LOG : 3,
+    INFO : 4,
+    DEBUG : 5,
+	ALL: 6,
+	DEFAULT: 6
+};
+
+console.level = CONSOLE_LEVEL.DEFAULT;
+
+// Save the original methods
+console._error = console.error;
+console._warn = console.warn;
+console._log = console.log;
+console._info = console.info;
+console._debug = console.debug;
+
+// Wrap console methods
+console.error = function () {
+  if (this.level >= CONSOLE_LEVEL.ERROR) this._error.apply(this, arguments);
+};
+
+console.warn = function () {
+  if (this.level >= CONSOLE_LEVEL.WARN) this._warn.apply(this, arguments);
+};
+
+console.log = function () {
+  if (this.level >= CONSOLE_LEVEL.LOG) this._log.apply(this, arguments);
+};
+
+console.info = function () {
+  if (this.level >= CONSOLE_LEVEL.INFO) this._info.apply(this, arguments);
+};
+
+console.debug = function () {
+  if (this.level >= CONSOLE_LEVEL.DEBUG) this._debug.apply(this, arguments);
+};