Add API retry-and-backoff + tests

.eslintrc.js

@@ -1,9 +1,6 @@
 module.exports = {
   extends: ["airbnb-base", "prettier"],
-  ignorePatterns: [
-    "tests/translations/**/*.js",
-    "uswds*.js"
-  ],
+  ignorePatterns: ["tests/translations/**/*.js", "uswds*.js"],
   rules: {
     // For imports in the browser, file extensions are always required.
     "import/extensions": ["error", "always"],
@@ -43,6 +40,21 @@ module.exports = {
         "class-methods-use-this": 0,
       },
     },
+    {
+      files: ["api-interop-layer/**/*.test.js"],
+      extends: ["airbnb-base", "prettier"],
+      rules: {
+        // This rule disallows using require() on files in devDependencies. But
+        // for test code, we'll rely on that heavily so we can disable the rule
+        // in here.
+        "import/no-extraneous-dependencies": [0],
+
+        // For imports in Node, file extensions are optional and discouraged as
+        // a matter of practice.
+        "import/extensions": { js: "always", json: "always" },
+      },
+      env: { mocha: true },
+    },
     {
       files: [
         "tests/**/*.js",

api-interop-layer/.gitignore

@@ -0,0 +1,2 @@
+.nyc_output
+coverage

api-interop-layer/data/db.js

@@ -1,5 +1,7 @@
 import mariadb from "mariadb";
 
+import { sleep } from "../util/sleep.js";
+
 export const openDatabase = async () => {
   const connectionDetails = {
     user: process.env.DB_USERNAME ?? "drupal",
@@ -13,13 +15,6 @@ export const openDatabase = async () => {
   return mariadb.createConnection(connectionDetails);
 };
 
-const sleep = (ms) =>
-  new Promise((resolve) => {
-    setTimeout(() => {
-      resolve();
-    }, ms);
-  });
-
 // Try to connect, wait, try again, wait, etc. If the database isn't ready after
 // 4 attempts and 30 seconds, we'll just fail.
 await openDatabase()