diff --git a/.gitignore b/.gitignore
index b0a273f0..fded70c1 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,5 +1,6 @@
 .vscode
 .idea
 /node_modules
+*/node_modules
 /dist
 /coverage
diff --git a/package-lock.json b/package-lock.json
index cafbec00..9af3fd78 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -1,12 +1,12 @@
 {
   "name": "fantasy-map-generator",
-  "version": "1.109.5",
+  "version": "1.110.0",
   "lockfileVersion": 3,
   "requires": true,
   "packages": {
     "": {
       "name": "fantasy-map-generator",
-      "version": "1.109.5",
+      "version": "1.110.0",
       "license": "MIT",
       "dependencies": {
         "alea": "^1.0.1",
@@ -18,8 +18,12 @@
         "@types/d3": "^7.4.3",
         "@types/delaunator": "^5.0.3",
         "@types/polylabel": "^1.1.3",
+        "@vitest/browser": "^4.0.18",
+        "@vitest/browser-playwright": "^4.0.18",
+        "playwright": "^1.57.0",
         "typescript": "^5.9.3",
-        "vite": "^7.3.1"
+        "vite": "^7.3.1",
+        "vitest": "^4.0.18"
       },
       "engines": {
         "node": ">=24.0.0"
@@ -467,6 +471,20 @@
         "node": ">=18"
       }
     },
+    "node_modules/@jridgewell/sourcemap-codec": {
+      "version": "1.5.5",
+      "resolved": "https://registry.npmjs.org/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.5.5.tgz",
+      "integrity": "sha512-cYQ9310grqxueWbl+WuIUIaiUaDcj7WOq5fVhEljNVgRfOUhY9fy2zTvfoqWsnebh8Sl70VScFbICvJnLKB0Og==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/@polka/url": {
+      "version": "1.0.0-next.29",
+      "resolved": "https://registry.npmjs.org/@polka/url/-/url-1.0.0-next.29.tgz",
+      "integrity": "sha512-wwQAWhWSuHaag8c4q/KN/vCoeOJYshAIvMQwD4GpSb3OiZklFfvAgmj0VCBBImRpuF/aFgIRzllXlVX93Jevww==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/@rollup/rollup-android-arm-eabi": {
       "version": "4.55.1",
       "resolved": "https://registry.npmjs.org/@rollup/rollup-android-arm-eabi/-/rollup-android-arm-eabi-4.55.1.tgz",
@@ -817,6 +835,24 @@
         "win32"
       ]
     },
+    "node_modules/@standard-schema/spec": {
+      "version": "1.1.0",
+      "resolved": "https://registry.npmjs.org/@standard-schema/spec/-/spec-1.1.0.tgz",
+      "integrity": "sha512-l2aFy5jALhniG5HgqrD6jXLi/rUWrKvqN/qJx6yoJsgKhblVd+iqqU4RCXavm/jPityDo5TCvKMnpjKnOriy0w==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/@types/chai": {
+      "version": "5.2.3",
+      "resolved": "https://registry.npmjs.org/@types/chai/-/chai-5.2.3.tgz",
+      "integrity": "sha512-Mw558oeA9fFbv65/y4mHtXDs9bPnFMZAL/jxdPFUpOHHIXX91mcgEHbS5Lahr+pwZFR8A7GQleRWeI6cGFC2UA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/deep-eql": "*",
+        "assertion-error": "^2.0.1"
+      }
+    },
     "node_modules/@types/d3": {
       "version": "7.4.3",
       "resolved": "https://registry.npmjs.org/@types/d3/-/d3-7.4.3.tgz",
@@ -1101,6 +1137,13 @@
         "@types/d3-selection": "*"
       }
     },
+    "node_modules/@types/deep-eql": {
+      "version": "4.0.2",
+      "resolved": "https://registry.npmjs.org/@types/deep-eql/-/deep-eql-4.0.2.tgz",
+      "integrity": "sha512-c9h9dVVMigMPc4bwTvC5dxqtqJZwQPePsWjPlpSOnojbor6pGqdk541lfA7AqFQr5pB1BRdq0juY9db81BwyFw==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/@types/delaunator": {
       "version": "5.0.3",
       "resolved": "https://registry.npmjs.org/@types/delaunator/-/delaunator-5.0.3.tgz",
@@ -1129,12 +1172,191 @@
       "dev": true,
       "license": "MIT"
     },
+    "node_modules/@vitest/browser": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/@vitest/browser/-/browser-4.0.18.tgz",
+      "integrity": "sha512-gVQqh7paBz3gC+ZdcCmNSWJMk70IUjDeVqi+5m5vYpEHsIwRgw3Y545jljtajhkekIpIp5Gg8oK7bctgY0E2Ng==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/mocker": "4.0.18",
+        "@vitest/utils": "4.0.18",
+        "magic-string": "^0.30.21",
+        "pixelmatch": "7.1.0",
+        "pngjs": "^7.0.0",
+        "sirv": "^3.0.2",
+        "tinyrainbow": "^3.0.3",
+        "ws": "^8.18.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      },
+      "peerDependencies": {
+        "vitest": "4.0.18"
+      }
+    },
+    "node_modules/@vitest/browser-playwright": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/@vitest/browser-playwright/-/browser-playwright-4.0.18.tgz",
+      "integrity": "sha512-gfajTHVCiwpxRj1qh0Sh/5bbGLG4F/ZH/V9xvFVoFddpITfMta9YGow0W6ZpTTORv2vdJuz9TnrNSmjKvpOf4g==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "@vitest/browser": "4.0.18",
+        "@vitest/mocker": "4.0.18",
+        "tinyrainbow": "^3.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      },
+      "peerDependencies": {
+        "playwright": "*",
+        "vitest": "4.0.18"
+      },
+      "peerDependenciesMeta": {
+        "playwright": {
+          "optional": false
+        }
+      }
+    },
+    "node_modules/@vitest/expect": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/@vitest/expect/-/expect-4.0.18.tgz",
+      "integrity": "sha512-8sCWUyckXXYvx4opfzVY03EOiYVxyNrHS5QxX3DAIi5dpJAAkyJezHCP77VMX4HKA2LDT/Jpfo8i2r5BE3GnQQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@standard-schema/spec": "^1.0.0",
+        "@types/chai": "^5.2.2",
+        "@vitest/spy": "4.0.18",
+        "@vitest/utils": "4.0.18",
+        "chai": "^6.2.1",
+        "tinyrainbow": "^3.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/mocker": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/@vitest/mocker/-/mocker-4.0.18.tgz",
+      "integrity": "sha512-HhVd0MDnzzsgevnOWCBj5Otnzobjy5wLBe4EdeeFGv8luMsGcYqDuFRMcttKWZA5vVO8RFjexVovXvAM4JoJDQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/spy": "4.0.18",
+        "estree-walker": "^3.0.3",
+        "magic-string": "^0.30.21"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      },
+      "peerDependencies": {
+        "msw": "^2.4.9",
+        "vite": "^6.0.0 || ^7.0.0-0"
+      },
+      "peerDependenciesMeta": {
+        "msw": {
+          "optional": true
+        },
+        "vite": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/@vitest/pretty-format": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/@vitest/pretty-format/-/pretty-format-4.0.18.tgz",
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+    "node_modules/@vitest/snapshot": {
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+      "dev": true,
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+      "dependencies": {
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+        "magic-string": "^0.30.21",
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+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/@vitest/spy/-/spy-4.0.18.tgz",
+      "integrity": "sha512-cbQt3PTSD7P2OARdVW3qWER5EGq7PHlvE+QfzSC0lbwO+xnt7+XH06ZzFjFRgzUX//JmpxrCu92VdwvEPlWSNw==",
+      "dev": true,
+      "license": "MIT",
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
+    "node_modules/@vitest/utils": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/@vitest/utils/-/utils-4.0.18.tgz",
+      "integrity": "sha512-msMRKLMVLWygpK3u2Hybgi4MNjcYJvwTb0Ru09+fOyCXIgT5raYP041DRRdiJiI3k/2U6SEbAETB3YtBrUkCFA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@vitest/pretty-format": "4.0.18",
+        "tinyrainbow": "^3.0.3"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      }
+    },
     "node_modules/alea": {
       "version": "1.0.1",
       "resolved": "https://registry.npmjs.org/alea/-/alea-1.0.1.tgz",
       "integrity": "sha512-QU+wv+ziDXaMxRdsQg/aH7sVfWdhKps5YP97IIwFkHCsbDZA3k87JXoZ5/iuemf4ntytzIWeScrRpae8+lDrXA==",
       "license": "MIT"
     },
+    "node_modules/assertion-error": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/assertion-error/-/assertion-error-2.0.1.tgz",
+      "integrity": "sha512-Izi8RQcffqCeNVgFigKli1ssklIbpHnCYc6AknXGYoB6grJqyeby7jv12JUQgmTAnIDnbck1uxksT4dzN3PWBA==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=12"
+      }
+    },
+    "node_modules/chai": {
+      "version": "6.2.2",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-6.2.2.tgz",
+      "integrity": "sha512-NUPRluOfOiTKBKvWPtSD4PhFvWCqOi0BGStNWs57X9js7XGTprSmFoz5F0tWhR4WPjNeR9jXqdC7/UpSJTnlRg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/commander": {
       "version": "7.2.0",
       "resolved": "https://registry.npmjs.org/commander/-/commander-7.2.0.tgz",
@@ -1555,6 +1777,13 @@
         "robust-predicates": "^3.0.2"
       }
     },
+    "node_modules/es-module-lexer": {
+      "version": "1.7.0",
+      "resolved": "https://registry.npmjs.org/es-module-lexer/-/es-module-lexer-1.7.0.tgz",
+      "integrity": "sha512-jEQoCwk8hyb2AZziIOLhDqpm5+2ww5uIE6lkO/6jcOCusfk6LhMHpXXfBLXTZ7Ydyt0j4VoUQv6uGNYbdW+kBA==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/esbuild": {
       "version": "0.27.2",
       "resolved": "https://registry.npmjs.org/esbuild/-/esbuild-0.27.2.tgz",
@@ -1597,6 +1826,26 @@
         "@esbuild/win32-x64": "0.27.2"
       }
     },
+    "node_modules/estree-walker": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/estree-walker/-/estree-walker-3.0.3.tgz",
+      "integrity": "sha512-7RUKfXgSMMkzt6ZuXmqapOurLGPPfgj6l9uRZ7lRGolvk0y2yocc35LdcxKC5PQZdn2DMqioAQ2NoWcrTKmm6g==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@types/estree": "^1.0.0"
+      }
+    },
+    "node_modules/expect-type": {
+      "version": "1.3.0",
+      "resolved": "https://registry.npmjs.org/expect-type/-/expect-type-1.3.0.tgz",
+      "integrity": "sha512-knvyeauYhqjOYvQ66MznSMs83wmHrCycNEN6Ao+2AeYEfxUIkuiVxdEa1qlGEPK+We3n0THiDciYSsCcgW/DoA==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=12.0.0"
+      }
+    },
     "node_modules/fdir": {
       "version": "6.5.0",
       "resolved": "https://registry.npmjs.org/fdir/-/fdir-6.5.0.tgz",
@@ -1651,6 +1900,26 @@
         "node": ">=12"
       }
     },
+    "node_modules/magic-string": {
+      "version": "0.30.21",
+      "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.21.tgz",
+      "integrity": "sha512-vd2F4YUyEXKGcLHoq+TEyCjxueSeHnFxyyjNp80yg0XV4vUhnDer/lvvlqM/arB5bXQN5K2/3oinyCRyx8T2CQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@jridgewell/sourcemap-codec": "^1.5.5"
+      }
+    },
+    "node_modules/mrmime": {
+      "version": "2.0.1",
+      "resolved": "https://registry.npmjs.org/mrmime/-/mrmime-2.0.1.tgz",
+      "integrity": "sha512-Y3wQdFg2Va6etvQ5I82yUhGdsKrcYox6p7FfL1LbK2J4V01F9TGlepTIhnK24t7koZibmg82KGglhA1XK5IsLQ==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=10"
+      }
+    },
     "node_modules/nanoid": {
       "version": "3.3.11",
       "resolved": "https://registry.npmjs.org/nanoid/-/nanoid-3.3.11.tgz",
@@ -1670,6 +1939,24 @@
         "node": "^10 || ^12 || ^13.7 || ^14 || >=15.0.1"
       }
     },
+    "node_modules/obug": {
+      "version": "2.1.1",
+      "resolved": "https://registry.npmjs.org/obug/-/obug-2.1.1.tgz",
+      "integrity": "sha512-uTqF9MuPraAQ+IsnPf366RG4cP9RtUi7MLO1N3KEc+wb0a6yKpeL0lmk2IB1jY5KHPAlTc6T/JRdC/YqxHNwkQ==",
+      "dev": true,
+      "funding": [
+        "https://github.com/sponsors/sxzz",
+        "https://opencollective.com/debug"
+      ],
+      "license": "MIT"
+    },
+    "node_modules/pathe": {
+      "version": "2.0.3",
+      "resolved": "https://registry.npmjs.org/pathe/-/pathe-2.0.3.tgz",
+      "integrity": "sha512-WUjGcAqP1gQacoQe+OBJsFA7Ld4DyXuUIjZ5cc75cLHvJ7dtNsTugphxIADwspS+AraAUePCKrSVtPLFj/F88w==",
+      "dev": true,
+      "license": "MIT"
+    },
     "node_modules/picocolors": {
       "version": "1.1.1",
       "resolved": "https://registry.npmjs.org/picocolors/-/picocolors-1.1.1.tgz",
@@ -1691,6 +1978,76 @@
         "url": "https://github.com/sponsors/jonschlinkert"
       }
     },
+    "node_modules/pixelmatch": {
+      "version": "7.1.0",
+      "resolved": "https://registry.npmjs.org/pixelmatch/-/pixelmatch-7.1.0.tgz",
+      "integrity": "sha512-1wrVzJ2STrpmONHKBy228LM1b84msXDUoAzVEl0R8Mz4Ce6EPr+IVtxm8+yvrqLYMHswREkjYFaMxnyGnaY3Ng==",
+      "dev": true,
+      "license": "ISC",
+      "dependencies": {
+        "pngjs": "^7.0.0"
+      },
+      "bin": {
+        "pixelmatch": "bin/pixelmatch"
+      }
+    },
+    "node_modules/playwright": {
+      "version": "1.57.0",
+      "resolved": "https://registry.npmjs.org/playwright/-/playwright-1.57.0.tgz",
+      "integrity": "sha512-ilYQj1s8sr2ppEJ2YVadYBN0Mb3mdo9J0wQ+UuDhzYqURwSoW4n1Xs5vs7ORwgDGmyEh33tRMeS8KhdkMoLXQw==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "dependencies": {
+        "playwright-core": "1.57.0"
+      },
+      "bin": {
+        "playwright": "cli.js"
+      },
+      "engines": {
+        "node": ">=18"
+      },
+      "optionalDependencies": {
+        "fsevents": "2.3.2"
+      }
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+    "node_modules/playwright-core": {
+      "version": "1.57.0",
+      "resolved": "https://registry.npmjs.org/playwright-core/-/playwright-core-1.57.0.tgz",
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+      "dev": true,
+      "license": "Apache-2.0",
+      "bin": {
+        "playwright-core": "cli.js"
+      },
+      "engines": {
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+      "resolved": "https://registry.npmjs.org/fsevents/-/fsevents-2.3.2.tgz",
+      "integrity": "sha512-xiqMQR4xAeHTuB9uWm+fFRcIOgKBMiOBP+eXiyT7jsgVCq1bkVygt00oASowB7EdtpOHaaPgKt812P9ab+DDKA==",
+      "dev": true,
+      "hasInstallScript": true,
+      "license": "MIT",
+      "optional": true,
+      "os": [
+        "darwin"
+      ],
+      "engines": {
+        "node": "^8.16.0 || ^10.6.0 || >=11.0.0"
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+    "node_modules/pngjs": {
+      "version": "7.0.0",
+      "resolved": "https://registry.npmjs.org/pngjs/-/pngjs-7.0.0.tgz",
+      "integrity": "sha512-LKWqWJRhstyYo9pGvgor/ivk2w94eSjE3RGVuzLGlr3NmD8bf7RcYGze1mNdEHRP6TRP6rMuDHk5t44hnTRyow==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
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     "node_modules/polylabel": {
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@@ -1792,6 +2149,28 @@
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       "license": "MIT"
     },
+    "node_modules/siginfo": {
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+      "resolved": "https://registry.npmjs.org/siginfo/-/siginfo-2.0.0.tgz",
+      "integrity": "sha512-ybx0WO1/8bSBLEWXZvEd7gMW3Sn3JFlW3TvX1nREbDLRNQNaeNN8WK0meBwPdAaOI7TtRRRJn/Es1zhrrCHu7g==",
+      "dev": true,
+      "license": "ISC"
+    },
+    "node_modules/sirv": {
+      "version": "3.0.2",
+      "resolved": "https://registry.npmjs.org/sirv/-/sirv-3.0.2.tgz",
+      "integrity": "sha512-2wcC/oGxHis/BoHkkPwldgiPSYcpZK3JU28WoMVv55yHJgcZ8rlXvuG9iZggz+sU1d4bRgIGASwyWqjxu3FM0g==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "@polka/url": "^1.0.0-next.24",
+        "mrmime": "^2.0.0",
+        "totalist": "^3.0.0"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/source-map-js": {
       "version": "1.2.1",
       "resolved": "https://registry.npmjs.org/source-map-js/-/source-map-js-1.2.1.tgz",
@@ -1802,6 +2181,37 @@
         "node": ">=0.10.0"
       }
     },
+    "node_modules/stackback": {
+      "version": "0.0.2",
+      "resolved": "https://registry.npmjs.org/stackback/-/stackback-0.0.2.tgz",
+      "integrity": "sha512-1XMJE5fQo1jGH6Y/7ebnwPOBEkIEnT4QF32d5R1+VXdXveM0IBMJt8zfaxX1P3QhVwrYe+576+jkANtSS2mBbw==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/std-env": {
+      "version": "3.10.0",
+      "resolved": "https://registry.npmjs.org/std-env/-/std-env-3.10.0.tgz",
+      "integrity": "sha512-5GS12FdOZNliM5mAOxFRg7Ir0pWz8MdpYm6AY6VPkGpbA7ZzmbzNcBJQ0GPvvyWgcY7QAhCgf9Uy89I03faLkg==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/tinybench": {
+      "version": "2.9.0",
+      "resolved": "https://registry.npmjs.org/tinybench/-/tinybench-2.9.0.tgz",
+      "integrity": "sha512-0+DUvqWMValLmha6lr4kD8iAMK1HzV0/aKnCtWb9v9641TnP/MFb7Pc2bxoxQjTXAErryXVgUOfv2YqNllqGeg==",
+      "dev": true,
+      "license": "MIT"
+    },
+    "node_modules/tinyexec": {
+      "version": "1.0.2",
+      "resolved": "https://registry.npmjs.org/tinyexec/-/tinyexec-1.0.2.tgz",
+      "integrity": "sha512-W/KYk+NFhkmsYpuHq5JykngiOCnxeVL8v8dFnqxSD8qEEdRfXk1SDM6JzNqcERbcGYj9tMrDQBYV9cjgnunFIg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
     "node_modules/tinyglobby": {
       "version": "0.2.15",
       "resolved": "https://registry.npmjs.org/tinyglobby/-/tinyglobby-0.2.15.tgz",
@@ -1825,6 +2235,26 @@
       "integrity": "sha512-gRa9gwYU3ECmQYv3lslts5hxuIa90veaEcxDYuu3QGOIAEM2mOZkVHp48ANJuu1CURtRdHKUBY5Lm1tHV+sD4g==",
       "license": "ISC"
     },
+    "node_modules/tinyrainbow": {
+      "version": "3.0.3",
+      "resolved": "https://registry.npmjs.org/tinyrainbow/-/tinyrainbow-3.0.3.tgz",
+      "integrity": "sha512-PSkbLUoxOFRzJYjjxHJt9xro7D+iilgMX/C9lawzVuYiIdcihh9DXmVibBe8lmcFrRi/VzlPjBxbN7rH24q8/Q==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=14.0.0"
+      }
+    },
+    "node_modules/totalist": {
+      "version": "3.0.1",
+      "resolved": "https://registry.npmjs.org/totalist/-/totalist-3.0.1.tgz",
+      "integrity": "sha512-sf4i37nQ2LBx4m3wB74y+ubopq6W/dIzXg0FDGjsYnZHVa1Da8FH853wlL2gtUhg+xJXjfk3kUZS3BRoQeoQBQ==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=6"
+      }
+    },
     "node_modules/typescript": {
       "version": "5.9.3",
       "resolved": "https://registry.npmjs.org/typescript/-/typescript-5.9.3.tgz",
@@ -1845,6 +2275,7 @@
       "integrity": "sha512-w+N7Hifpc3gRjZ63vYBXA56dvvRlNWRczTdmCBBa+CotUzAPf5b7YMdMR/8CQoeYE5LX3W4wj6RYTgonm1b9DA==",
       "dev": true,
       "license": "MIT",
+      "peer": true,
       "dependencies": {
         "esbuild": "^0.27.0",
         "fdir": "^6.5.0",
@@ -1913,6 +2344,124 @@
           "optional": true
         }
       }
+    },
+    "node_modules/vitest": {
+      "version": "4.0.18",
+      "resolved": "https://registry.npmjs.org/vitest/-/vitest-4.0.18.tgz",
+      "integrity": "sha512-hOQuK7h0FGKgBAas7v0mSAsnvrIgAvWmRFjmzpJ7SwFHH3g1k2u37JtYwOwmEKhK6ZO3v9ggDBBm0La1LCK4uQ==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "@vitest/expect": "4.0.18",
+        "@vitest/mocker": "4.0.18",
+        "@vitest/pretty-format": "4.0.18",
+        "@vitest/runner": "4.0.18",
+        "@vitest/snapshot": "4.0.18",
+        "@vitest/spy": "4.0.18",
+        "@vitest/utils": "4.0.18",
+        "es-module-lexer": "^1.7.0",
+        "expect-type": "^1.2.2",
+        "magic-string": "^0.30.21",
+        "obug": "^2.1.1",
+        "pathe": "^2.0.3",
+        "picomatch": "^4.0.3",
+        "std-env": "^3.10.0",
+        "tinybench": "^2.9.0",
+        "tinyexec": "^1.0.2",
+        "tinyglobby": "^0.2.15",
+        "tinyrainbow": "^3.0.3",
+        "vite": "^6.0.0 || ^7.0.0",
+        "why-is-node-running": "^2.3.0"
+      },
+      "bin": {
+        "vitest": "vitest.mjs"
+      },
+      "engines": {
+        "node": "^20.0.0 || ^22.0.0 || >=24.0.0"
+      },
+      "funding": {
+        "url": "https://opencollective.com/vitest"
+      },
+      "peerDependencies": {
+        "@edge-runtime/vm": "*",
+        "@opentelemetry/api": "^1.9.0",
+        "@types/node": "^20.0.0 || ^22.0.0 || >=24.0.0",
+        "@vitest/browser-playwright": "4.0.18",
+        "@vitest/browser-preview": "4.0.18",
+        "@vitest/browser-webdriverio": "4.0.18",
+        "@vitest/ui": "4.0.18",
+        "happy-dom": "*",
+        "jsdom": "*"
+      },
+      "peerDependenciesMeta": {
+        "@edge-runtime/vm": {
+          "optional": true
+        },
+        "@opentelemetry/api": {
+          "optional": true
+        },
+        "@types/node": {
+          "optional": true
+        },
+        "@vitest/browser-playwright": {
+          "optional": true
+        },
+        "@vitest/browser-preview": {
+          "optional": true
+        },
+        "@vitest/browser-webdriverio": {
+          "optional": true
+        },
+        "@vitest/ui": {
+          "optional": true
+        },
+        "happy-dom": {
+          "optional": true
+        },
+        "jsdom": {
+          "optional": true
+        }
+      }
+    },
+    "node_modules/why-is-node-running": {
+      "version": "2.3.0",
+      "resolved": "https://registry.npmjs.org/why-is-node-running/-/why-is-node-running-2.3.0.tgz",
+      "integrity": "sha512-hUrmaWBdVDcxvYqnyh09zunKzROWjbZTiNy8dBEjkS7ehEDQibXJ7XvlmtbwuTclUiIyN+CyXQD4Vmko8fNm8w==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "siginfo": "^2.0.0",
+        "stackback": "0.0.2"
+      },
+      "bin": {
+        "why-is-node-running": "cli.js"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
+    "node_modules/ws": {
+      "version": "8.19.0",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-8.19.0.tgz",
+      "integrity": "sha512-blAT2mjOEIi0ZzruJfIhb3nps74PRWTCz1IjglWEEpQl5XS/UNama6u2/rjFkDDouqr4L67ry+1aGIALViWjDg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=10.0.0"
+      },
+      "peerDependencies": {
+        "bufferutil": "^4.0.1",
+        "utf-8-validate": ">=5.0.2"
+      },
+      "peerDependenciesMeta": {
+        "bufferutil": {
+          "optional": true
+        },
+        "utf-8-validate": {
+          "optional": true
+        }
+      }
     }
   }
 }
diff --git a/package.json b/package.json
index 7a17e01b..1c802071 100644
--- a/package.json
+++ b/package.json
@@ -16,14 +16,20 @@
   "scripts": {
     "dev": "vite",
     "build": "tsc && vite build",
-    "preview": "vite preview"
+    "preview": "vite preview",
+    "test": "vitest",
+    "test:browser": "vitest --config=vitest.browser.config.ts"
   },
   "devDependencies": {
     "@types/d3": "^7.4.3",
     "@types/delaunator": "^5.0.3",
     "@types/polylabel": "^1.1.3",
+    "@vitest/browser": "^4.0.18",
+    "@vitest/browser-playwright": "^4.0.18",
+    "playwright": "^1.57.0",
     "typescript": "^5.9.3",
-    "vite": "^7.3.1"
+    "vite": "^7.3.1",
+    "vitest": "^4.0.18"
   },
   "dependencies": {
     "alea": "^1.0.1",
diff --git a/src/utils/stringUtils.test.ts b/src/utils/stringUtils.test.ts
new file mode 100644
index 00000000..10da484f
--- /dev/null
+++ b/src/utils/stringUtils.test.ts
@@ -0,0 +1,8 @@
+import { expect, describe, it } from 'vitest'
+import { round } from './stringUtils'
+
+describe('round', () => {
+  it('should be able to handle undefined input', () => {
+    expect(round(undefined)).toBe("");
+  });
+})
\ No newline at end of file
diff --git a/vitest.browser.config.ts b/vitest.browser.config.ts
new file mode 100644
index 00000000..cf8528b8
--- /dev/null
+++ b/vitest.browser.config.ts
@@ -0,0 +1,18 @@
+import { defineConfig } from 'vitest/config'
+import { playwright } from '@vitest/browser-playwright'
+
+export default defineConfig({
+  test: {
+    browser: {
+      enabled: true,
+      provider: playwright(),
+      // https://vitest.dev/config/browser/playwright
+      instances: [
+        { name: 'chromium', browser: 'chromium' },
+      ],
+      locators: {
+        testIdAttribute: 'id',
+      },
+    },
+  },
+})