Introduce basic js unit tests

Signed-off-by: Thomas Citharel <tcit@tcit.fr>

js/tests/unit/.eslintrc.js

@@ -0,0 +1,15 @@
+module.exports = {
+  env: {
+    mocha: true,
+  },
+  globals: {
+    expect: true,
+    sinon: true,
+  },
+  rules: {
+    "import/no-extraneous-dependencies": [
+      "error",
+      { devDependencies: ["**/*.test.js", "**/*.spec.js"] },
+    ],
+  },
+};