fix(log.js): Move from MPL log lib to MIT (#405)

.gitignore

@@ -5,6 +5,5 @@
 node_modules
 .idea
 yarn-error.log
-yarn.lock
 .DS_Store
 build

README.md

@@ -163,3 +163,7 @@ The developers gratefully acknowledge their research support:
 - The [Neuroimage Analysis Center](http://nac.spl.harvard.edu)
 - The [National Center for Image Guided Therapy](http://ncigt.org)
 - The [NCI Imaging Data Commons](https://imagingdatacommons.github.io/) NCI Imaging Data Commons: contract number 19X037Q from Leidos Biomedical Research under Task Order HHSN26100071 from NCI
+
+## Logging
+
+This library uses [loglevel](https://github.com/pimterry/loglevel) for logging. By default, the log level is set to "warn". You can change the log level by setting the `LOG_LEVEL` environment variable or by using the `setLevel` method in your code.

jest.setup.js

@@ -0,0 +1,21 @@
+// Mock loglevel
+const createMockLogger = () => ({
+    debug: jest.fn(),
+    info: jest.fn(),
+    warn: jest.fn(),
+    error: jest.fn(),
+    setLevel: jest.fn()
+});
+
+const mockLog = createMockLogger();
+
+mockLog.create = jest.fn(name => {
+    const namedLogger = createMockLogger();
+    namedLogger.name = name;
+    return namedLogger;
+});
+
+jest.mock("loglevel", () => mockLog);
+
+// Optionally, if you want to make the mock available globally for easier assertions
+global.mockLog = mockLog;