Feature/jest in core (#899)

* WIP

* Replace ava with jest in core

* Update package-lock

* Exclude tests from transpilation

* Expect transformPluginFile to throw

* Mock fetch in audius tests

* Mock fetch in audius tests

packages/core/__mocks__/electron-store.js

@@ -0,0 +1,9 @@
+class Electron {
+  prototype = {}
+  get() {
+    return '';
+  }
+  set() {}
+}
+
+module.exports = Electron;

packages/core/__mocks__/electron-timber.js

@@ -0,0 +1,6 @@
+class MockLogger {
+  static log() {}
+  static error() {}
+}
+
+module.exports = MockLogger;

packages/core/__mocks__/electron.js

@@ -0,0 +1,17 @@
+module.exports = {
+  app: {
+    getPath: () => { }
+  },
+  remote: {
+    transformSource: () => { },
+    app: {
+      getPath: () => { }
+    },
+    dialog: {
+      showOpenDialog: jest.fn(async () => Promise.resolve({
+        canceled: false,
+        filePaths: ['test file.txt']
+      }))
+    }
+  }
+};

packages/core/jest.config.ts

@@ -0,0 +1,7 @@
+
+export default async () => ({
+  transform: {
+    '^.+\\.(ts|tsx)$': 'ts-jest',
+    '^.+\\.(js|jsx)$': 'ts-jest'
+  }
+});