diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index fd9947c..7ec0fa7 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -7,7 +7,21 @@ on:
     branches: [master]
 
 jobs:
-  build:
+  static-checks:
+    runs-on: ubuntu-latest
+
+    steps:
+      - uses: actions/checkout@v7.0.0
+      - name: Use Node.js 24.x
+        uses: actions/setup-node@v6.4.0
+        with:
+          node-version: 24.x
+          cache: npm
+      - run: npm ci
+      - run: npm run format:check
+      - run: npm run lint
+
+  test:
     runs-on: ubuntu-latest
 
     strategy:
@@ -20,8 +34,7 @@ jobs:
         uses: actions/setup-node@v6.4.0
         with:
           node-version: ${{ matrix.node-version }}
+          cache: npm
       - run: npm ci
-      - run: npm run format:check
-      - run: npm run lint
       - run: npm run build --if-present
       - run: npm test
diff --git a/package.json b/package.json
index 3e5b881..7eadcbc 100644
--- a/package.json
+++ b/package.json
@@ -18,7 +18,7 @@
   },
   "homepage": "https://github.com/parcelLab/regionIdentifier",
   "scripts": {
-    "test": "node --test test/tests.js",
+    "test": "node --test",
     "lint": "eslint .",
     "format": "prettier --write .",
     "format:check": "prettier --check ."
diff --git a/test/fixtures/countries-postal-codes.json b/test/fixtures/countries-postal-codes.json
new file mode 100644
index 0000000..d809caa
--- /dev/null
+++ b/test/fixtures/countries-postal-codes.json
@@ -0,0 +1,544 @@
+{
+  "Austria": [
+    {
+      "name": "AUT",
+      "zip": "1999",
+      "result": "AT-9",
+      "usingGoogle": false
+    },
+    {
+      "name": "Austria",
+      "usingGoogle": false,
+      "zip": "1999",
+      "result": "AT-9"
+    }
+  ],
+  "Deutschland": [
+    {
+      "name": "DEU",
+      "zip": "6578",
+      "result": "DE-TH",
+      "usingGoogle": false
+    }
+  ],
+  "Belgium": [
+    {
+      "name": "BEL",
+      "zip": "1701",
+      "result": "BE-VLG",
+      "usingGoogle": false
+    }
+  ],
+  "Switzerland": [
+    {
+      "name": "CHE",
+      "zip": "2333",
+      "result": "CH-BE",
+      "usingGoogle": false
+    },
+    {
+      "name": "CHE",
+      "zip": "9488",
+      "result": "CH-SG",
+      "usingGoogle": false
+    }
+  ],
+  "Spain": [
+    {
+      "name": "ESP",
+      "zip": "04004",
+      "result": "ES-AN",
+      "usingGoogle": false
+    }
+  ],
+  "France": [
+    {
+      "name": "FRA",
+      "zip": "25090",
+      "result": "FR-I",
+      "usingGoogle": false
+    },
+    {
+      "name": "FRA",
+      "zip": "92440",
+      "result": "FR-J",
+      "usingGoogle": false
+    },
+    {
+      "name": "FRA",
+      "zip": "75116",
+      "result": "FR-J",
+      "usingGoogle": false
+    },
+    {
+      "name": "FRA",
+      "zip": "51000",
+      "result": "FR-G",
+      "usingGoogle": false
+    },
+    {
+      "name": "FRA",
+      "zip": "51100",
+      "result": "FR-G",
+      "usingGoogle": false
+    },
+    {
+      "name": "FRA",
+      "zip": "75020",
+      "result": "FR-J",
+      "usingGoogle": false
+    },
+    {
+      "name": "FR",
+      "zip": "25090",
+      "result": "FR-I",
+      "usingGoogle": false
+    },
+    {
+      "name": "FR",
+      "zip": "87200",
+      "result": "FR-L",
+      "usingGoogle": false
+    },
+    {
+      "name": "FR",
+      "zip": "87200 CEDEX 1",
+      "result": "FR-L",
+      "usingGoogle": false
+    },
+    {
+      "name": "FR",
+      "zip": "61100",
+      "result": "FR-P",
+      "usingGoogle": false
+    },
+    {
+      "name": "FR",
+      "zip": "81000",
+      "result": "FR-N",
+      "usingGoogle": false
+    }
+  ],
+  "United Kingdom": [
+    {
+      "name": "GBR",
+      "zip": "PA13 4PS",
+      "result": "GB-SCT",
+      "usingGoogle": false
+    },
+    {
+      "name": "GBR",
+      "zip": "EC2N 1AR",
+      "result": "GB-ENG",
+      "usingGoogle": false
+    },
+    {
+      "name": "GBR",
+      "zip": "FY83QN",
+      "result": "GB-ENG",
+      "usingGoogle": false
+    },
+    {
+      "name": "GBR",
+      "zip": "CF466RT",
+      "result": "GB-WLS",
+      "usingGoogle": false
+    },
+    {
+      "name": "GBR",
+      "zip": "AL10 9BL",
+      "result": "GB-ENG",
+      "usingGoogle": false
+    },
+    {
+      "name": "GBR",
+      "zip": "m14 5pq",
+      "result": "GB-ENG",
+      "usingGoogle": false
+    },
+    {
+      "name": "GBR",
+      "zip": "Po10 8Eg",
+      "result": "GB-ENG",
+      "usingGoogle": false
+    },
+    {
+      "name": "GBR",
+      "zip": "L5 3QN",
+      "result": "GB-ENG",
+      "usingGoogle": false
+    }
+  ],
+  "Italy": [
+    {
+      "name": "ITA",
+      "zip": "67033",
+      "result": "IT-65",
+      "usingGoogle": false
+    },
+    {
+      "name": "ITA",
+      "zip": "41121",
+      "result": "IT-45",
+      "usingGoogle": false
+    }
+  ],
+  "India": [
+    {
+      "name": "IND",
+      "zip": "110001",
+      "result": "IN-DL",
+      "usingGoogle": false
+    }
+  ],
+  "Ireland": [
+    {
+      "name": "IRL",
+      "zip": "D02 X285",
+      "result": "IE-L",
+      "usingGoogle": false
+    }
+  ],
+  "Romania": [
+    {
+      "name": "ROU",
+      "zip": "010011",
+      "result": "RO-B",
+      "usingGoogle": false
+    }
+  ],
+  "Hungary": [
+    {
+      "name": "HUN",
+      "zip": "1011",
+      "result": "HU-BU",
+      "usingGoogle": false
+    }
+  ],
+  "Japan": [
+    {
+      "name": "JPN",
+      "zip": "100-0001",
+      "result": "JP-13",
+      "usingGoogle": false
+    },
+    {
+      "name": "JPN",
+      "zip": "530-0001",
+      "result": "JP-27",
+      "usingGoogle": false
+    }
+  ],
+  "Brazil": [
+    {
+      "name": "BRA",
+      "zip": "69900-000",
+      "result": "BR-AC",
+      "usingGoogle": false
+    }
+  ],
+  "South Korea": [
+    {
+      "name": "KOR",
+      "zip": "01000",
+      "result": "KR-11",
+      "usingGoogle": false
+    }
+  ],
+  "Lithuania": [
+    {
+      "name": "LTU",
+      "zip": "62001",
+      "result": "LT-03",
+      "usingGoogle": false
+    }
+  ],
+  "Luxembourg": [
+    {
+      "name": "LUX",
+      "zip": "L-4795",
+      "result": "LU-CA",
+      "usingGoogle": false
+    }
+  ],
+  "Portugal": [
+    {
+      "name": "PRT",
+      "zip": "3020-740",
+      "result": "PT-01",
+      "usingGoogle": false
+    }
+  ],
+  "Slovakia": [
+    {
+      "name": "SVK",
+      "zip": "049 01",
+      "result": "SK-BC",
+      "usingGoogle": false
+    }
+  ],
+  "Turkey": [
+    {
+      "name": "TUR",
+      "zip": "01010",
+      "result": "TR-01",
+      "usingGoogle": false
+    }
+  ],
+  "Netherlands": [
+    {
+      "name": "NLD",
+      "zip": "3541",
+      "result": "NL-UT",
+      "usingGoogle": false
+    },
+    {
+      "name": "NLD",
+      "zip": "6869 VC",
+      "result": "NL-GE",
+      "usingGoogle": false
+    },
+    {
+      "name": "NLD",
+      "zip": "2294 HC",
+      "result": "NL-ZH",
+      "usingGoogle": false
+    },
+    {
+      "name": "NLD",
+      "zip": "2294HC",
+      "result": "NL-ZH",
+      "usingGoogle": false
+    }
+  ],
+  "Canada": [
+    {
+      "name": "CAN",
+      "zip": "X1A 0E2",
+      "result": "CA-NT",
+      "usingGoogle": false
+    },
+    {
+      "name": "CAN",
+      "zip": "X1A 0E2",
+      "result": "CA-NT",
+      "usingGoogle": false
+    },
+    {
+      "name": "CAN",
+      "zip": "X1A0E2",
+      "result": "CA-NT",
+      "usingGoogle": false
+    },
+    {
+      "name": "CAN",
+      "zip": "G1P 2J1",
+      "result": "CA-QC",
+      "usingGoogle": false
+    },
+    {
+      "name": "CAN",
+      "zip": "S0J 0G0",
+      "result": "CA-SK",
+      "usingGoogle": false
+    }
+  ],
+  "Mexico": [
+    {
+      "name": "MEX",
+      "zip": "06000",
+      "result": "MX-CMX",
+      "usingGoogle": false
+    }
+  ],
+  "Serbia": [
+    {
+      "name": "SRB",
+      "zip": "11000",
+      "result": "RS-00",
+      "usingGoogle": false
+    },
+    {
+      "name": "SRB",
+      "zip": "11320",
+      "result": "RS-10",
+      "usingGoogle": false
+    },
+    {
+      "name": "SRB",
+      "zip": "18230",
+      "result": "RS-15",
+      "usingGoogle": false
+    },
+    {
+      "name": "SRB",
+      "zip": "24430",
+      "result": "RS-03",
+      "usingGoogle": false
+    },
+    {
+      "name": "SRB",
+      "zip": "21000",
+      "result": "RS-VO",
+      "usingGoogle": false
+    },
+    {
+      "name": "SRB",
+      "zip": "38000",
+      "result": "RS-KM",
+      "usingGoogle": false
+    }
+  ],
+  "United States": [
+    {
+      "name": "USA",
+      "zip": "972022239",
+      "result": "US-OR",
+      "usingGoogle": false
+    },
+    {
+      "name": "USA",
+      "zip": "06103",
+      "result": "US-CT",
+      "usingGoogle": false
+    },
+    {
+      "name": "USA",
+      "zip": "00646",
+      "result": "US-PR",
+      "usingGoogle": false
+    },
+    {
+      "name": "USA",
+      "zip": "96799",
+      "result": "US-AS",
+      "usingGoogle": false
+    },
+    {
+      "name": "USA",
+      "zip": "96921",
+      "result": "US-GU",
+      "usingGoogle": false
+    },
+    {
+      "name": "USA",
+      "zip": "96951",
+      "result": "US-MP",
+      "usingGoogle": false
+    },
+    {
+      "name": "USA",
+      "zip": "00831",
+      "result": "US-VI",
+      "usingGoogle": false
+    },
+    {
+      "name": "USA",
+      "zip": "10038",
+      "result": "US-NY",
+      "usingGoogle": false
+    }
+  ],
+  "Qatar": [
+    {
+      "name": "QAT",
+      "zip": "06000",
+      "result": null,
+      "usingGoogle": false
+    }
+  ],
+  "Sweden": [
+    {
+      "name": "SWE",
+      "zip": "11337",
+      "result": "SE-AB",
+      "usingGoogle": false
+    },
+    {
+      "name": "SWE",
+      "zip": "95435",
+      "result": "SE-BD",
+      "usingGoogle": false
+    },
+    {
+      "name": "SWE",
+      "zip": "23531",
+      "result": "SE-M",
+      "usingGoogle": false
+    },
+    {
+      "name": "SWE",
+      "zip": "10000",
+      "result": "SE-AB",
+      "usingGoogle": false
+    },
+    {
+      "name": "SWE",
+      "zip": "99999",
+      "result": "SE-BD",
+      "usingGoogle": false
+    },
+    {
+      "name": "SWE",
+      "zip": "81999",
+      "result": "SE-C",
+      "usingGoogle": false
+    }
+  ],
+  "Finland": [
+    {
+      "name": "FIN",
+      "zip": "00940",
+      "result": "FI-18",
+      "usingGoogle": false
+    },
+    {
+      "name": "FIN",
+      "zip": "70840",
+      "result": "FI-15",
+      "usingGoogle": false
+    },
+    {
+      "name": "FIN",
+      "zip": "96900",
+      "result": "FI-10",
+      "usingGoogle": false
+    },
+    {
+      "name": "FIN",
+      "zip": "00100",
+      "result": "FI-18",
+      "usingGoogle": false
+    },
+    {
+      "name": "FIN",
+      "zip": "99990",
+      "result": "FI-10",
+      "usingGoogle": false
+    },
+    {
+      "name": "FIN",
+      "zip": "20200",
+      "result": "FI-19",
+      "usingGoogle": false
+    },
+    {
+      "name": "FIN",
+      "zip": "22100",
+      "result": "FI-01",
+      "usingGoogle": false
+    },
+    {
+      "name": "AUS",
+      "zip": "0841",
+      "result": "AU-NT",
+      "usingGoogle": false
+    },
+    {
+      "name": "AUS",
+      "zip": "2111",
+      "result": "AU-NSW",
+      "usingGoogle": false
+    }
+  ]
+}
diff --git a/test/tests.js b/test/tests.js
index 310a7a9..96d6b1e 100644
--- a/test/tests.js
+++ b/test/tests.js
@@ -1,554 +1,40 @@
-const assert = require('node:assert/strict');
+const { default: axios } = require('axios');
+const { equal, rejects, match } = require('node:assert/strict');
 const { describe, it } = require('node:test');
 
+const { GoogleMapsAPIError } = require('../lib/errors');
 const RegionIdentifier = require('../lib/region');
+const countriesPostalCodes = require('./fixtures/countries-postal-codes.json');
 
 const identifier = new RegionIdentifier('<API KEY>');
 
-const countriesPostalCodes = {
-  'Austria': [
-    {
-      name: 'AUT',
-      zip: '1999',
-      result: 'AT-9',
-      usingGoogle: false,
-    },
-    {
-      name: 'Austria',
-      usingGoogle: false,
-      zip: '1999',
-      result: 'AT-9',
-    },
-  ],
-  'Deutschland': [
-    {
-      name: 'DEU',
-      zip: '6578',
-      result: 'DE-TH',
-      usingGoogle: false,
-    },
-  ],
-  'Belgium': [
-    {
-      name: 'BEL',
-      zip: '1701',
-      result: 'BE-VLG',
-      usingGoogle: false,
-    },
-  ],
-  'Switzerland': [
-    {
-      name: 'CHE',
-      zip: '2333',
-      result: 'CH-BE',
-      usingGoogle: false,
-    },
-    {
-      name: 'CHE',
-      zip: '9488',
-      result: 'CH-SG',
-      usingGoogle: false,
-    },
-  ],
-  'Spain': [
-    {
-      name: 'ESP',
-      zip: '04004',
-      result: 'ES-AN',
-      usingGoogle: false,
-    },
-  ],
-  'France': [
-    {
-      name: 'FRA',
-      zip: '25090',
-      result: 'FR-I',
-      usingGoogle: false,
-    },
-    {
-      name: 'FRA',
-      zip: '92440',
-      result: 'FR-J',
-      usingGoogle: false,
-    },
-    {
-      name: 'FRA',
-      zip: '75116',
-      result: 'FR-J',
-      usingGoogle: false,
-    },
-    {
-      name: 'FRA',
-      zip: '51000',
-      result: 'FR-G',
-      usingGoogle: false,
-    },
-    {
-      name: 'FRA',
-      zip: '51100',
-      result: 'FR-G',
-      usingGoogle: false,
-    },
-    {
-      name: 'FRA',
-      zip: '75020',
-      result: 'FR-J',
-      usingGoogle: false,
-    },
-    {
-      name: 'FR',
-      zip: '25090',
-      result: 'FR-I',
-      usingGoogle: false,
-    },
-    {
-      name: 'FR',
-      zip: '87200',
-      result: 'FR-L',
-      usingGoogle: false,
-    },
-    {
-      name: 'FR',
-      zip: '87200 CEDEX 1',
-      result: 'FR-L',
-      usingGoogle: false,
-    },
-    {
-      name: 'FR',
-      zip: '61100',
-      result: 'FR-P',
-      usingGoogle: false,
-    },
-    {
-      name: 'FR',
-      zip: '81000',
-      result: 'FR-N',
-      usingGoogle: false,
-    },
-  ],
-  'United Kingdom': [
-    {
-      name: 'GBR',
-      zip: 'PA13 4PS',
-      result: 'GB-SCT',
-      usingGoogle: false,
-    },
-    {
-      name: 'GBR',
-      zip: 'EC2N 1AR',
-      result: 'GB-ENG',
-      usingGoogle: false,
-    },
-    {
-      name: 'GBR',
-      zip: 'FY83QN',
-      result: 'GB-ENG',
-      usingGoogle: false,
-    },
-    {
-      name: 'GBR',
-      zip: 'CF466RT',
-      result: 'GB-WLS',
-      usingGoogle: false,
-    },
-    {
-      name: 'GBR',
-      zip: 'AL10 9BL',
-      result: 'GB-ENG',
-      usingGoogle: false,
-    },
-    {
-      name: 'GBR',
-      zip: 'm14 5pq',
-      result: 'GB-ENG',
-      usingGoogle: false,
-    },
-    {
-      name: 'GBR',
-      zip: 'Po10 8Eg',
-      result: 'GB-ENG',
-      usingGoogle: false,
-    },
-    {
-      name: 'GBR',
-      zip: 'L5 3QN',
-      result: 'GB-ENG',
-      usingGoogle: false,
-    },
-  ],
-  'Italy': [
-    {
-      name: 'ITA',
-      zip: '67033',
-      result: 'IT-65',
-      usingGoogle: false,
-    },
-    {
-      name: 'ITA',
-      zip: '41121',
-      result: 'IT-45',
-      usingGoogle: false,
-    },
-  ],
-  'India': [
-    {
-      name: 'IND',
-      zip: '110001',
-      result: 'IN-DL',
-      usingGoogle: false,
-    },
-  ],
-  'Ireland': [
-    {
-      name: 'IRL',
-      zip: 'D02 X285',
-      result: 'IE-L',
-      usingGoogle: false,
-    },
-  ],
-  'Romania': [
-    {
-      name: 'ROU',
-      zip: '010011',
-      result: 'RO-B',
-      usingGoogle: false,
-    },
-  ],
-  'Hungary': [
-    {
-      name: 'HUN',
-      zip: '1011',
-      result: 'HU-BU',
-      usingGoogle: false,
-    },
-  ],
-  'Japan': [
-    {
-      name: 'JPN',
-      zip: '100-0001',
-      result: 'JP-13',
-      usingGoogle: false,
-    },
-    {
-      name: 'JPN',
-      zip: '530-0001',
-      result: 'JP-27',
-      usingGoogle: false,
-    },
-  ],
-  'Brazil': [
-    {
-      name: 'BRA',
-      zip: '69900-000',
-      result: 'BR-AC',
-      usingGoogle: false,
-    },
-  ],
-  'South Korea': [
-    {
-      name: 'KOR',
-      zip: '01000',
-      result: 'KR-11',
-      usingGoogle: false,
-    },
-  ],
-  'Lithuania': [
-    {
-      name: 'LTU',
-      zip: '62001',
-      result: 'LT-03',
-      usingGoogle: false,
-    },
-  ],
-  'Luxembourg': [
-    {
-      name: 'LUX',
-      zip: 'L-4795',
-      result: 'LU-CA',
-      usingGoogle: false,
-    },
-  ],
-  'Portugal': [
-    {
-      name: 'PRT',
-      zip: '3020-740',
-      result: 'PT-01',
-      usingGoogle: false,
-    },
-  ],
-  'Slovakia': [
-    {
-      name: 'SVK',
-      zip: '049 01',
-      result: 'SK-BC',
-      usingGoogle: false,
-    },
-  ],
-  'Turkey': [
-    {
-      name: 'TUR',
-      zip: '01010',
-      result: 'TR-01',
-      usingGoogle: false,
-    },
-  ],
-  'Netherlands': [
-    {
-      name: 'NLD',
-      zip: '3541',
-      result: 'NL-UT',
-      usingGoogle: false,
-    },
-    {
-      name: 'NLD',
-      zip: '6869 VC',
-      result: 'NL-GE',
-      usingGoogle: false,
-    },
-    {
-      name: 'NLD',
-      zip: '2294 HC',
-      result: 'NL-ZH',
-      usingGoogle: false,
-    },
-    {
-      name: 'NLD',
-      zip: '2294HC',
-      result: 'NL-ZH',
-      usingGoogle: false,
-    },
-  ],
-  'Canada': [
-    {
-      name: 'CAN',
-      zip: 'X1A 0E2',
-      result: 'CA-NT',
-      usingGoogle: false,
-    },
-    {
-      name: 'CAN',
-      zip: 'X1A 0E2',
-      result: 'CA-NT',
-      usingGoogle: false,
-    },
-    {
-      name: 'CAN',
-      zip: 'X1A0E2',
-      result: 'CA-NT',
-      usingGoogle: false,
-    },
-    {
-      name: 'CAN',
-      zip: 'G1P 2J1',
-      result: 'CA-QC',
-      usingGoogle: false,
-    },
-    {
-      name: 'CAN',
-      zip: 'S0J 0G0',
-      result: 'CA-SK',
-      usingGoogle: false,
-    },
-  ],
-  'Mexico': [
-    {
-      name: 'MEX',
-      zip: '06000',
-      result: 'MX-CMX',
-      usingGoogle: false,
-    },
-  ],
-  'Serbia': [
-    {
-      name: 'SRB',
-      zip: '11000',
-      result: 'RS-00',
-      usingGoogle: false,
-    },
-    {
-      name: 'SRB',
-      zip: '11320',
-      result: 'RS-10',
-      usingGoogle: false,
-    },
-    {
-      name: 'SRB',
-      zip: '18230',
-      result: 'RS-15',
-      usingGoogle: false,
-    },
-    {
-      name: 'SRB',
-      zip: '24430',
-      result: 'RS-03',
-      usingGoogle: false,
-    },
-    {
-      name: 'SRB',
-      zip: '21000',
-      result: 'RS-VO',
-      usingGoogle: false,
-    },
-    {
-      name: 'SRB',
-      zip: '38000',
-      result: 'RS-KM',
-      usingGoogle: false,
-    },
-  ],
-  'United States': [
-    {
-      name: 'USA',
-      zip: '972022239',
-      result: 'US-OR',
-      usingGoogle: false,
-    },
-    {
-      name: 'USA',
-      zip: '06103',
-      result: 'US-CT',
-      usingGoogle: false,
-    },
-    {
-      name: 'USA',
-      zip: '00646',
-      result: 'US-PR',
-      usingGoogle: false,
-    },
-    {
-      name: 'USA',
-      zip: '96799',
-      result: 'US-AS',
-      usingGoogle: false,
-    },
-    {
-      name: 'USA',
-      zip: '96921',
-      result: 'US-GU',
-      usingGoogle: false,
-    },
-    {
-      name: 'USA',
-      zip: '96951',
-      result: 'US-MP',
-      usingGoogle: false,
-    },
-    {
-      name: 'USA',
-      zip: '00831',
-      result: 'US-VI',
-      usingGoogle: false,
-    },
-    {
-      name: 'USA',
-      zip: '10038',
-      result: 'US-NY',
-      usingGoogle: false,
-    },
-  ],
-  'Qatar': [
-    {
-      name: 'QAT',
-      zip: '06000',
-      result: null,
-      usingGoogle: false,
-    },
-  ],
-  'Sweden': [
-    {
-      name: 'SWE',
-      zip: '11337',
-      result: 'SE-AB',
-      usingGoogle: false,
-    },
-    {
-      name: 'SWE',
-      zip: '95435',
-      result: 'SE-BD',
-      usingGoogle: false,
-    },
-    {
-      name: 'SWE',
-      zip: '23531',
-      result: 'SE-M',
-      usingGoogle: false,
-    },
-    {
-      name: 'SWE',
-      zip: '10000',
-      result: 'SE-AB',
-      usingGoogle: false,
-    },
-    {
-      name: 'SWE',
-      zip: '99999',
-      result: 'SE-BD',
-      usingGoogle: false,
-    },
-    {
-      name: 'SWE',
-      zip: '81999',
-      result: 'SE-C',
-      usingGoogle: false,
-    },
-  ],
-  'Finland': [
-    {
-      name: 'FIN',
-      zip: '00940',
-      result: 'FI-18',
-      usingGoogle: false,
-    },
-    {
-      name: 'FIN',
-      zip: '70840',
-      result: 'FI-15',
-      usingGoogle: false,
-    },
-    {
-      name: 'FIN',
-      zip: '96900',
-      result: 'FI-10',
-      usingGoogle: false,
-    },
-    {
-      name: 'FIN',
-      zip: '00100',
-      result: 'FI-18',
-      usingGoogle: false,
-    },
-    {
-      name: 'FIN',
-      zip: '99990',
-      result: 'FI-10',
-      usingGoogle: false,
-    },
-    {
-      name: 'FIN',
-      zip: '20200',
-      result: 'FI-19',
-      usingGoogle: false,
-    },
-    {
-      name: 'FIN',
-      zip: '22100',
-      result: 'FI-01',
-      usingGoogle: false,
-    },
-    {
-      name: 'AUS',
-      zip: '0841',
-      result: 'AU-NT',
-      usingGoogle: false,
-    },
-    {
-      name: 'AUS',
-      zip: '2111',
-      result: 'AU-NSW',
-      usingGoogle: false,
-    },
-  ],
-};
+function googleMapsResponse(regionShortName) {
+  return {
+    data: {
+      results: [
+        {
+          address_components: [
+            {
+              short_name: regionShortName,
+              types: ['administrative_area_level_1'],
+            },
+          ],
+        },
+      ],
+    },
+  };
+}
+
+async function withMockedGoogleGet(mockGet, callback) {
+  const originalGet = axios.get;
+  axios.get = mockGet;
+
+  try {
+    return await callback();
+  } finally {
+    axios.get = originalGet;
+  }
+}
 
 describe('REGION IDENTIFIER', () => {
   Object.entries(countriesPostalCodes).forEach(([countryName, countryPostalCodes]) => {
@@ -557,10 +43,86 @@ describe('REGION IDENTIFIER', () => {
         it(`result for: ${test.name} with zip code: ${test.zip}`, async () => {
           const [region, googleUsed] = await identifier.get(test.name, test.zip);
 
-          assert.equal(region, test.result);
-          assert.equal(googleUsed, test.usingGoogle);
+          equal(region, test.result);
+          equal(googleUsed, test.usingGoogle);
         });
       });
     });
   });
 });
+
+describe('Fallback and error handling', () => {
+  it('returns null without Google Maps when static data has no matching zip code', async () => {
+    const [region, googleUsed] = await withMockedGoogleGet(
+      async () => {
+        throw new Error('Google Maps should not be called for static misses');
+      },
+      () => identifier.get('DEU', '00000'),
+    );
+
+    equal(region, null);
+    equal(googleUsed, false);
+  });
+
+  it('throws when country or zip code is missing', async () => {
+    await rejects(() => identifier.get('', '12345'));
+    await rejects(() => identifier.get('DEU', ''));
+  });
+
+  it('detects regions with Google Maps when called directly', async () => {
+    const region = await withMockedGoogleGet(
+      async (url) => {
+        match(url, /maps\.googleapis\.com/);
+        match(url, /country%3DQAT%20postal_code%3D06000/);
+        return googleMapsResponse('DA');
+      },
+      () => identifier.detectWithGoogle({ alpha2: 'QA', alpha3: 'QAT' }, '06000'),
+    );
+
+    equal(region, 'QA-DA');
+  });
+
+  it('throws when country cannot be resolved', async () => {
+    await rejects(() => identifier.get('Atlantis', '12345'));
+  });
+
+  it('wraps Google Maps request failures', async () => {
+    await withMockedGoogleGet(
+      async () => {
+        throw new Error('network unavailable');
+      },
+      async () => {
+        await rejects(
+          () => identifier.detectWithGoogle({ alpha2: 'QA', alpha3: 'QAT' }, '06000'),
+          (err) => err instanceof GoogleMapsAPIError,
+        );
+      },
+    );
+  });
+
+  it('throws when Google Maps response has no administrative region', async () => {
+    await withMockedGoogleGet(
+      async () => ({
+        data: {
+          results: [
+            {
+              address_components: [{ short_name: 'QA', types: ['country'] }],
+            },
+          ],
+        },
+      }),
+      async () => {
+        await rejects(
+          () => identifier.detectWithGoogle({ alpha2: 'QA', alpha3: 'QAT' }, '06000'),
+          (err) => err instanceof GoogleMapsAPIError,
+        );
+      },
+    );
+  });
+
+  it('returns region display names', () => {
+    equal(identifier.getNameFromCountryAndRegion('DEU', 'DE-TH'), 'Thüringen');
+    equal(identifier.getNameFromCountryAndRegion('DEU', 'UNKNOWN'), null);
+    equal(identifier.getNameFromCountryAndRegion('Atlantis', 'DE-TH'), null);
+  });
+});