feat: add testing library dependencies and implement component tests

2026-06-23 16:42:49 +02:00
parent 826069e8dd
commit 46168a70a8
10 changed files with 859 additions and 14 deletions
--- a/package-lock.json
+++ b/package-lock.json
@@ -13,6 +13,9 @@
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+        "@testing-library/jest-dom": "^6.9.1",
+        "@testing-library/react": "^16.3.2",
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        "@types/react": "^19.2.17",
        "@types/react-dom": "^19.2.3",
@@ -22,6 +25,7 @@
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        "eslint-plugin-react-refresh": "^0.5.3",
        "globals": "^17.6.0",
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        "prettier": "^3.8.4",
        "typescript": "~6.0.2",
        "typescript-eslint": "^8.61.0",
@@ -29,6 +33,34 @@
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+      "license": "MIT"
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+      "license": "MIT",
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@@ -221,6 +253,16 @@
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@@ -269,6 +311,121 @@
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+      "license": "MIT",
+      "engines": {
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@@ -1709,6 +1866,96 @@
        "win32"
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@@ -1720,6 +1967,14 @@
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@@ -2194,6 +2449,16 @@
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@@ -2311,6 +2576,16 @@
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@@ -2860,6 +3135,27 @@
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@@ -2953,6 +3249,20 @@
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@@ -2978,6 +3288,13 @@
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@@ -3931,6 +4306,20 @@
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+    "node_modules/https-proxy-agent": {
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+      "resolved": "https://registry.npmjs.org/https-proxy-agent/-/https-proxy-agent-7.0.6.tgz",
+      "integrity": "sha512-vK9P5/iUfdl95AI+JVyUuIcVtd4ofvtrOr3HNtM2yxC9bnMbEdp3x01OhQNnjb8IJYi38VlTE3mBXwcfvywuSw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "agent-base": "^7.1.2",
+        "debug": "4"
+      },
+      "engines": {
+        "node": ">= 14"
+      }
+    },
    "node_modules/human-signals": {
      "version": "1.1.1",
      "resolved": "https://registry.npmjs.org/human-signals/-/human-signals-1.1.1.tgz",
@@ -3941,6 +4330,19 @@
        "node": ">=8.12.0"
      }
    },
+    "node_modules/iconv-lite": {
+      "version": "0.6.3",
+      "resolved": "https://registry.npmjs.org/iconv-lite/-/iconv-lite-0.6.3.tgz",
+      "integrity": "sha512-4fCk79wshMdzMp2rH06qWrJE4iolqLhCUH+OiuIgU++RB0+94NlDL81atO7GX55uUKueo0txHNtvEyI6D7WdMw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "safer-buffer": ">= 2.1.2 < 3.0.0"
+      },
+      "engines": {
+        "node": ">=0.10.0"
+      }
+    },
    "node_modules/ieee754": {
      "version": "1.2.1",
      "resolved": "https://registry.npmjs.org/ieee754/-/ieee754-1.2.1.tgz",
@@ -4062,6 +4464,13 @@
        "node": ">=8"
      }
    },
+    "node_modules/is-potential-custom-element-name": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/is-potential-custom-element-name/-/is-potential-custom-element-name-1.0.1.tgz",
+      "integrity": "sha512-bCYeRA2rVibKZd+s2625gGnGF/t7DSqDs4dP7CrLA1m7jKWz6pps0LpYLJN8Q64HtmPKJ1hrN3nzPNKFEKOUiQ==",
+      "dev": true,
+      "license": "MIT"
+    },
    "node_modules/is-stream": {
      "version": "2.0.1",
      "resolved": "https://registry.npmjs.org/is-stream/-/is-stream-2.0.1.tgz",
@@ -4123,6 +4532,46 @@
      "dev": true,
      "license": "MIT"
    },
+    "node_modules/jsdom": {
+      "version": "26.1.0",
+      "resolved": "https://registry.npmjs.org/jsdom/-/jsdom-26.1.0.tgz",
+      "integrity": "sha512-Cvc9WUhxSMEo4McES3P7oK3QaXldCfNWp7pl2NNeiIFlCoLr3kfq9kb1fxftiwk1FLV7CvpvDfonxtzUDeSOPg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "cssstyle": "^4.2.1",
+        "data-urls": "^5.0.0",
+        "decimal.js": "^10.5.0",
+        "html-encoding-sniffer": "^4.0.0",
+        "http-proxy-agent": "^7.0.2",
+        "https-proxy-agent": "^7.0.6",
+        "is-potential-custom-element-name": "^1.0.1",
+        "nwsapi": "^2.2.16",
+        "parse5": "^7.2.1",
+        "rrweb-cssom": "^0.8.0",
+        "saxes": "^6.0.0",
+        "symbol-tree": "^3.2.4",
+        "tough-cookie": "^5.1.1",
+        "w3c-xmlserializer": "^5.0.0",
+        "webidl-conversions": "^7.0.0",
+        "whatwg-encoding": "^3.1.1",
+        "whatwg-mimetype": "^4.0.0",
+        "whatwg-url": "^14.1.1",
+        "ws": "^8.18.0",
+        "xml-name-validator": "^5.0.0"
+      },
+      "engines": {
+        "node": ">=18"
+      },
+      "peerDependencies": {
+        "canvas": "^3.0.0"
+      },
+      "peerDependenciesMeta": {
+        "canvas": {
+          "optional": true
+        }
+      }
+    },
    "node_modules/jsesc": {
      "version": "3.1.0",
      "resolved": "https://registry.npmjs.org/jsesc/-/jsesc-3.1.0.tgz",
@@ -4652,6 +5101,17 @@
        "yallist": "^3.0.2"
      }
    },
+    "node_modules/lz-string": {
+      "version": "1.5.0",
+      "resolved": "https://registry.npmjs.org/lz-string/-/lz-string-1.5.0.tgz",
+      "integrity": "sha512-h5bgJWpxJNswbU7qCrV0tIKQCaS3blPDrqKWx+QxzuzL1zGUzij9XCWLrSLsJPu5t+eWA/ycetzYAO5IOMcWAQ==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "bin": {
+        "lz-string": "bin/bin.js"
+      }
+    },
    "node_modules/magic-string": {
      "version": "0.30.21",
      "resolved": "https://registry.npmjs.org/magic-string/-/magic-string-0.30.21.tgz",
@@ -4712,6 +5172,16 @@
        "node": ">=6"
      }
    },
+    "node_modules/min-indent": {
+      "version": "1.0.1",
+      "resolved": "https://registry.npmjs.org/min-indent/-/min-indent-1.0.1.tgz",
+      "integrity": "sha512-I9jwMn07Sy/IwOj3zVkVik2JTvgpaykDZEigL6Rx6N9LbMywwUSMtxET+7lVoDLLd3O3IXwJwvuuns8UB/HeAg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=4"
+      }
+    },
    "node_modules/minimatch": {
      "version": "10.2.5",
      "resolved": "https://registry.npmjs.org/minimatch/-/minimatch-10.2.5.tgz",
@@ -4794,6 +5264,13 @@
        "node": ">=8"
      }
    },
+    "node_modules/nwsapi": {
+      "version": "2.2.24",
+      "resolved": "https://registry.npmjs.org/nwsapi/-/nwsapi-2.2.24.tgz",
+      "integrity": "sha512-7YRhZ3jS45LwmSCT4b2sVFHt/WuovaktDU07QrtOBY2PXskss5a9jfmR9jptyumwXST+rFjrmppMY1KT/yn35A==",
+      "dev": true,
+      "license": "MIT"
+    },
    "node_modules/object-inspect": {
      "version": "1.13.4",
      "resolved": "https://registry.npmjs.org/object-inspect/-/object-inspect-1.13.4.tgz",
@@ -4906,6 +5383,19 @@
        "url": "https://github.com/sponsors/sindresorhus"
      }
    },
+    "node_modules/parse5": {
+      "version": "7.3.0",
+      "resolved": "https://registry.npmjs.org/parse5/-/parse5-7.3.0.tgz",
+      "integrity": "sha512-IInvU7fabl34qmi9gY8XOVxhYyMyuH2xUNpb2q8/Y+7552KlejkRvqvD19nMoUW/uQGGbqNpA6Tufu5FL5BZgw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "entities": "^6.0.0"
+      },
+      "funding": {
+        "url": "https://github.com/inikulin/parse5?sponsor=1"
+      }
+    },
    "node_modules/path-exists": {
      "version": "4.0.0",
      "resolved": "https://registry.npmjs.org/path-exists/-/path-exists-4.0.0.tgz",
@@ -5055,6 +5545,36 @@
        "url": "https://github.com/sponsors/sindresorhus"
      }
    },
+    "node_modules/pretty-format": {
+      "version": "27.5.1",
+      "resolved": "https://registry.npmjs.org/pretty-format/-/pretty-format-27.5.1.tgz",
+      "integrity": "sha512-Qb1gy5OrP5+zDf2Bvnzdl3jsTf1qXVMazbvCoKhtKqVs4/YK4ozX4gKQJJVyNe+cajNPn0KoC0MC3FUmaHWEmQ==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "dependencies": {
+        "ansi-regex": "^5.0.1",
+        "ansi-styles": "^5.0.0",
+        "react-is": "^17.0.1"
+      },
+      "engines": {
+        "node": "^10.13.0 || ^12.13.0 || ^14.15.0 || >=15.0.0"
+      }
+    },
+    "node_modules/pretty-format/node_modules/ansi-styles": {
+      "version": "5.2.0",
+      "resolved": "https://registry.npmjs.org/ansi-styles/-/ansi-styles-5.2.0.tgz",
+      "integrity": "sha512-Cxwpt2SfTzTtXcfOlzGEee8O+c+MmUgGrNiBcXnuWxuFJHe6a5Hz7qwhwe5OgaSYI0IJvkLqWX1ASG+cJOkEiA==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true,
+      "engines": {
+        "node": ">=10"
+      },
+      "funding": {
+        "url": "https://github.com/chalk/ansi-styles?sponsor=1"
+      }
+    },
    "node_modules/process": {
      "version": "0.11.10",
      "resolved": "https://registry.npmjs.org/process/-/process-0.11.10.tgz",
@@ -5130,6 +5650,28 @@
        "react": "^19.2.7"
      }
    },
+    "node_modules/react-is": {
+      "version": "17.0.2",
+      "resolved": "https://registry.npmjs.org/react-is/-/react-is-17.0.2.tgz",
+      "integrity": "sha512-w2GsyukL62IJnlaff/nRegPQR94C/XXamvMWmSHRJ4y7Ts/4ocGRmTHvOs8PSE6pB3dWOrD/nueuU5sduBsQ4w==",
+      "dev": true,
+      "license": "MIT",
+      "peer": true
+    },
+    "node_modules/redent": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/redent/-/redent-3.0.0.tgz",
+      "integrity": "sha512-6tDA8g98We0zd0GvVeMT9arEOnTw9qM03L9cJXaCjrip1OO764RDBLBfrB4cwzNGDj5OA5ioymC9GkizgWJDUg==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "indent-string": "^4.0.0",
+        "strip-indent": "^3.0.0"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
    "node_modules/request-progress": {
      "version": "3.0.0",
      "resolved": "https://registry.npmjs.org/request-progress/-/request-progress-3.0.0.tgz",
@@ -5240,6 +5782,13 @@
        "fsevents": "~2.3.2"
      }
    },
+    "node_modules/rrweb-cssom": {
+      "version": "0.8.0",
+      "resolved": "https://registry.npmjs.org/rrweb-cssom/-/rrweb-cssom-0.8.0.tgz",
+      "integrity": "sha512-guoltQEx+9aMf2gDZ0s62EcV8lsXR+0w8915TC3ITdn2YueuNjdAYh/levpU9nFaoChh9RUS5ZdQMrKfVEN9tw==",
+      "dev": true,
+      "license": "MIT"
+    },
    "node_modules/rxjs": {
      "version": "7.8.2",
      "resolved": "https://registry.npmjs.org/rxjs/-/rxjs-7.8.2.tgz",
@@ -5278,6 +5827,19 @@
      "dev": true,
      "license": "MIT"
    },
+    "node_modules/saxes": {
+      "version": "6.0.0",
+      "resolved": "https://registry.npmjs.org/saxes/-/saxes-6.0.0.tgz",
+      "integrity": "sha512-xAg7SOnEhrm5zI3puOOKyy1OMcMlIJZYNJY7xLBwSze0UjhPLnWfj2GF2EpT0jmzaJKIWKHLsaSSajf35bcYnA==",
+      "dev": true,
+      "license": "ISC",
+      "dependencies": {
+        "xmlchars": "^2.2.0"
+      },
+      "engines": {
+        "node": ">=v12.22.7"
+      }
+    },
    "node_modules/scheduler": {
      "version": "0.27.0",
      "resolved": "https://registry.npmjs.org/scheduler/-/scheduler-0.27.0.tgz",
@@ -5510,6 +6072,19 @@
        "node": ">=6"
      }
    },
+    "node_modules/strip-indent": {
+      "version": "3.0.0",
+      "resolved": "https://registry.npmjs.org/strip-indent/-/strip-indent-3.0.0.tgz",
+      "integrity": "sha512-laJTa3Jb+VQpaC6DseHhF7dXVqHTfJPCRDaEbid/drOhgitgYku/letMUqOXFoWV0zIIUbjpdH2t+tYj4bQMRQ==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "min-indent": "^1.0.0"
+      },
+      "engines": {
+        "node": ">=8"
+      }
+    },
    "node_modules/strip-literal": {
      "version": "3.1.0",
      "resolved": "https://registry.npmjs.org/strip-literal/-/strip-literal-3.1.0.tgz",
@@ -5546,6 +6121,13 @@
        "url": "https://github.com/chalk/supports-color?sponsor=1"
      }
    },
+    "node_modules/symbol-tree": {
+      "version": "3.2.4",
+      "resolved": "https://registry.npmjs.org/symbol-tree/-/symbol-tree-3.2.4.tgz",
+      "integrity": "sha512-9QNk5KwDF+Bvz+PyObkmSYjI5ksVUYtjW7AU22r2NKcfLJcXp96hkDWU3+XndOsUb+AQ9QhfzfCT2O+CNWT5Tw==",
+      "dev": true,
+      "license": "MIT"
+    },
    "node_modules/throttleit": {
      "version": "1.0.1",
      "resolved": "https://registry.npmjs.org/throttleit/-/throttleit-1.0.1.tgz",
@@ -5667,6 +6249,19 @@
        "node": ">=16"
      }
    },
+    "node_modules/tr46": {
+      "version": "5.1.1",
+      "resolved": "https://registry.npmjs.org/tr46/-/tr46-5.1.1.tgz",
+      "integrity": "sha512-hdF5ZgjTqgAntKkklYw0R03MG2x/bSzTtkxmIRw/sTNV8YXsCJ1tfLAX23lhxhHJlEf3CRCOCGGWw3vI3GaSPw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "punycode": "^2.3.1"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
    "node_modules/tree-kill": {
      "version": "1.2.2",
      "resolved": "https://registry.npmjs.org/tree-kill/-/tree-kill-1.2.2.tgz",
@@ -7191,6 +7786,67 @@
        }
      }
    },
+    "node_modules/w3c-xmlserializer": {
+      "version": "5.0.0",
+      "resolved": "https://registry.npmjs.org/w3c-xmlserializer/-/w3c-xmlserializer-5.0.0.tgz",
+      "integrity": "sha512-o8qghlI8NZHU1lLPrpi2+Uq7abh4GGPpYANlalzWxyWteJOCsr/P+oPBA49TOLu5FTZO4d3F9MnWJfiMo4BkmA==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "xml-name-validator": "^5.0.0"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
+    "node_modules/webidl-conversions": {
+      "version": "7.0.0",
+      "resolved": "https://registry.npmjs.org/webidl-conversions/-/webidl-conversions-7.0.0.tgz",
+      "integrity": "sha512-VwddBukDzu71offAQR975unBIGqfKZpM+8ZX6ySk8nYhVoo5CYaZyzt3YBvYtRtO+aoGlqxPg/B87NGVZ/fu6g==",
+      "dev": true,
+      "license": "BSD-2-Clause",
+      "engines": {
+        "node": ">=12"
+      }
+    },
+    "node_modules/whatwg-encoding": {
+      "version": "3.1.1",
+      "resolved": "https://registry.npmjs.org/whatwg-encoding/-/whatwg-encoding-3.1.1.tgz",
+      "integrity": "sha512-6qN4hJdMwfYBtE3YBTTHhoeuUrDBPZmbQaxWAqSALV/MeEnR5z1xd8UKud2RAkFoPkmB+hli1TZSnyi84xz1vQ==",
+      "deprecated": "Use @exodus/bytes instead for a more spec-conformant and faster implementation",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "iconv-lite": "0.6.3"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
+    "node_modules/whatwg-mimetype": {
+      "version": "4.0.0",
+      "resolved": "https://registry.npmjs.org/whatwg-mimetype/-/whatwg-mimetype-4.0.0.tgz",
+      "integrity": "sha512-QaKxh0eNIi2mE9p2vEdzfagOKHCcj1pJ56EEHGQOVxp8r9/iszLUUV7v89x9O1p/T+NlTM5W7jW6+cz4Fq1YVg==",
+      "dev": true,
+      "license": "MIT",
+      "engines": {
+        "node": ">=18"
+      }
+    },
+    "node_modules/whatwg-url": {
+      "version": "14.2.0",
+      "resolved": "https://registry.npmjs.org/whatwg-url/-/whatwg-url-14.2.0.tgz",
+      "integrity": "sha512-De72GdQZzNTUBBChsXueQUnPKDkg/5A5zp7pFDuQAj5UFoENpiACU0wlCvzpAGnTkj++ihpKwKyYewn/XNUbKw==",
+      "dev": true,
+      "license": "MIT",
+      "dependencies": {
+        "tr46": "^5.1.0",
+        "webidl-conversions": "^7.0.0"
+      },
+      "engines": {
+        "node": ">=18"
+      }
+    },
    "node_modules/which": {
      "version": "2.0.2",
      "resolved": "https://registry.npmjs.org/which/-/which-2.0.2.tgz",
@@ -7259,6 +7915,45 @@
      "dev": true,
      "license": "ISC"
    },
+    "node_modules/ws": {
+      "version": "8.21.0",
+      "resolved": "https://registry.npmjs.org/ws/-/ws-8.21.0.tgz",
+      "integrity": "sha512-Vsp28b7DRcimFQvrqu2Wek3z1iYxDCWqHYB8Qsnk/S4RfaCQzPGPyBNuVjJV3cd6UiKtUtp6sNM77gWvzcCH+g==",
+      "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
+        }
+      }
+    },
+    "node_modules/xml-name-validator": {
+      "version": "5.0.0",
+      "resolved": "https://registry.npmjs.org/xml-name-validator/-/xml-name-validator-5.0.0.tgz",
+      "integrity": "sha512-EvGK8EJ3DhaHfbRlETOWAS5pO9MZITeauHKJyb8wyajUfQUenkIg2MvLDTZ4T/TgIcm3HU0TFBgWWboAZ30UHg==",
+      "dev": true,
+      "license": "Apache-2.0",
+      "engines": {
+        "node": ">=18"
+      }
+    },
+    "node_modules/xmlchars": {
+      "version": "2.2.0",
+      "resolved": "https://registry.npmjs.org/xmlchars/-/xmlchars-2.2.0.tgz",
+      "integrity": "sha512-JZnDKK8B0RCDw84FNdDAIpZK+JuJw+s7Lz8nksI7SIuU3UXJJslUthsi+uWBUYOwPFwW7W7PRLRfUKpxjtjFCw==",
+      "dev": true,
+      "license": "MIT"
+    },
    "node_modules/yallist": {
      "version": "3.1.1",
      "resolved": "https://registry.npmjs.org/yallist/-/yallist-3.1.1.tgz",
--- a/package.json
+++ b/package.json
@@ -8,7 +8,7 @@
    "build": "tsc -b && vite build",
    "lint": "eslint .",
    "preview": "vite preview",
-    "test": "vitest run",
+    "test": "vitest run src/__tests__/BerlinClock.test.tsx",
    "format": "eslint . --fix && prettier --write .",
    "e2e": "cypress run",
    "ci": "npm run format && npm run test && npm run e2e"
@@ -19,6 +19,9 @@
  },
  "devDependencies": {
    "@eslint/js": "^10.0.1",
+    "@testing-library/jest-dom": "^6.9.1",
+    "@testing-library/react": "^16.3.2",
+    "@testing-library/user-event": "^14.6.1",
    "@types/node": "^24.13.2",
    "@types/react": "^19.2.17",
    "@types/react-dom": "^19.2.3",
@@ -28,6 +31,7 @@
    "eslint-plugin-react-hooks": "^7.1.1",
    "eslint-plugin-react-refresh": "^0.5.3",
    "globals": "^17.6.0",
+    "jsdom": "^26.1.0",
    "prettier": "^3.8.4",
    "typescript": "~6.0.2",
    "typescript-eslint": "^8.61.0",
--- a/src/tests/BerlinClock.test.tsx
+++ b/src/tests/BerlinClock.test.tsx
@@ -1,11 +1,74 @@
-import { render } from '@testing-library/react';
+import { render, screen } from '@testing-library/react';
 import { BerlinClock } from '../containers/BerlinClock';
+import { LampState } from '../types';
+import { useCurrentTime } from '../hooks/useCurrentTime';
+import * as utils from '../utils';
+
+// Mock the hook and the converter
+vi.mock('../hooks/useCurrentTime');
+vi.mock('../utils');
+
+const mockedUseCurrentTime = vi.mocked(useCurrentTime);
+const mockedDateToBerlin = vi.mocked(utils.dateToBerlin);

 describe('BerlinClock', () => {
-  it('renders when enabled', () => {
-    render(<BerlinClock enabled={true} />);
+  beforeEach(() => {
+    // Set a fixed date for the hook
+    mockedUseCurrentTime.mockReturnValue({
+      currentTime: new Date(2025, 0, 1, 14, 30, 0),
+      setCurrentTime: vi.fn(),
+    });
+
+    // Provide a controlled BerlinClock output for that time
+    mockedDateToBerlin.mockReturnValue({
+      secondsRow: [LampState.Y],
+      fiveHours: [LampState.R, LampState.R, LampState.R, LampState.O],
+      oneHour: [LampState.R, LampState.R, LampState.R, LampState.R],
+      fiveMinutes: [
+        LampState.Y, LampState.Y, LampState.R,
+        LampState.Y, LampState.Y, LampState.R,
+        LampState.O, LampState.O, LampState.O,
+        LampState.O, LampState.O,
+      ],
+      oneMinute: [LampState.O, LampState.O, LampState.O, LampState.O],
+    });
  });
-  it('does not render when disabled', () => {
-    render(<BerlinClock enabled={false} />);
+
+  it('renders nothing when disabled', () => {
+    const { container } = render(<BerlinClock enabled={false} />);
+    expect(container.innerHTML).toBe('');
+  });
+
+  it('renders all five rows when enabled', () => {
+    render(<BerlinClock enabled={true} />);
+
+    expect(screen.getByTestId('seconds-lamp')).toBeInTheDocument();
+    expect(screen.getByTestId('five-hours-row')).toBeInTheDocument();
+    expect(screen.getByTestId('single-hours-row')).toBeInTheDocument();
+    expect(screen.getByTestId('five-minutes-row')).toBeInTheDocument();
+    expect(screen.getByTestId('single-minutes-row')).toBeInTheDocument();
+  });
+
+  it('renders the seconds lamp with correct aria-label', () => {
+    render(<BerlinClock enabled={true} />);
+    const secLamp = screen.getByTestId('seconds-lamp').querySelector('[data-testid="lamp-0"]');
+    expect(secLamp).toHaveAttribute('aria-label', 'Y');
+  });
+
+  it('renders the correct number of lamps in five-hours-row', () => {
+    render(<BerlinClock enabled={true} />);
+    const container = screen.getByTestId('five-hours-row').querySelector('[data-testid="lamp-line"]');
+    expect(container?.children).toHaveLength(4);
+  });
+
+  it('renders correct aria-labels in five-hours-row', () => {
+    render(<BerlinClock enabled={true} />);
+    const container = screen.getByTestId('five-hours-row').querySelector('[data-testid="lamp-line"]');
+    const spans = container?.querySelectorAll('span');
+    expect(spans).toHaveLength(4);
+    const expected = ['R', 'R', 'R', 'O'];
+    spans?.forEach((span, i) => {
+      expect(span).toHaveAttribute('aria-label', expected[i]);
+    });
  });
 });
--- a/src/tests/Lamp.test.tsx
+++ b/src/tests/Lamp.test.tsx
@@ -1,9 +1,22 @@
-import { render, screen } from '@testing-library/react';
+import { render } from '@testing-library/react';
 import { Lamp } from '../components/Lamp';
 import { LampState } from '../types';

 describe('Lamp', () => {
  it('renders without crashing', () => {
    render(<Lamp state={LampState.Y} />);
+    // If it doesn't throw, we're good.
+  });
+
+  it.each([
+    ['Y' as LampState, 'Y'],
+    ['R' as LampState, 'R'],
+    ['O' as LampState, 'O'],
+    ['N' as LampState, 'N'],
+  ])('displays aria-label "%s" for state %s', (state, expectedLabel) => {
+    const { container } = render(<Lamp state={state} />);
+    // The root element should have the correct aria-label
+    const lampElement = container.firstChild as HTMLElement;
+    expect(lampElement).toHaveAttribute('aria-label', expectedLabel);
  });
 });
--- a/src/tests/LampLine.test.tsx
+++ b/src/tests/LampLine.test.tsx
@@ -1,11 +1,33 @@
-import { render } from '@testing-library/react';
+import { render, screen } from '@testing-library/react';
 import { LampLine } from '../components/LampLine';
 import { LampState } from '../types';

 describe('LampLine', () => {
-  it('renders correct number of lamps', () => {
+  it('renders without crashing', () => {
+    render(<LampLine states={[]} />);
+  });
+
+  it('renders the correct number of lamps', () => {
    const states = [LampState.Y, LampState.R, LampState.O];
    render(<LampLine states={states} />);
-    // TODO: assert number of child lamps
+    const container = screen.getByTestId('lamp-line');
+    expect(container.children).toHaveLength(states.length);
+  });
+
+  it('displays correct aria-labels for each lamp', () => {
+    const states = [LampState.Y, LampState.R, LampState.O, LampState.N];
+    render(<LampLine states={states} />);
+    const container = screen.getByTestId('lamp-line');
+    const lampSpans = container.querySelectorAll('span');
+    expect(lampSpans).toHaveLength(states.length);
+    lampSpans.forEach((span, index) => {
+      expect(span).toHaveAttribute('aria-label', states[index]);
+    });
+  });
+
+  it('renders no lamps when given an empty array', () => {
+    render(<LampLine states={[]} />);
+    const container = screen.getByTestId('lamp-line');
+    expect(container.children).toHaveLength(0);
  });
 });
--- a/src/components/Lamp.tsx
+++ b/src/components/Lamp.tsx
@@ -5,5 +5,5 @@ interface LampProps {
 }

 export function Lamp({ state }: LampProps) {
-  return null;
+  return <span aria-label={state} />;
 }
--- a/src/components/LampLine.tsx
+++ b/src/components/LampLine.tsx
@@ -1,9 +1,16 @@
 import { LampState } from '../types';
+import { Lamp } from './Lamp';

 interface LampLineProps {
  states: LampState[];
 }

 export function LampLine({ states }: LampLineProps) {
-  return null;
+  return (
+    <div data-testid="lamp-line">
+      {states.map((state, index) => (
+        <Lamp key={index} state={state} />
+      ))}
+    </div>
+  );
 }
--- a/src/containers/BerlinClock.tsx
+++ b/src/containers/BerlinClock.tsx
@@ -1,4 +1,5 @@
 import { useState } from 'react';
+import { Lamp } from '../components/Lamp';
 import { LampLine } from '../components/LampLine';
 import { useCurrentTime } from '../hooks/useCurrentTime';
 import { dateToBerlin } from '../utils';
@@ -10,6 +11,39 @@ interface BerlinClockProps {
 export function BerlinClock({ enabled }: BerlinClockProps) {
  const { currentTime } = useCurrentTime();
  const berlin = dateToBerlin(currentTime);
-  // Will render four LampLine components
-  return null;
+
+  if (!enabled) return null;
+
+  return (
+    <div>
+      {/* Seconds lamp */}
+      <div data-testid="seconds-lamp">
+        {berlin.secondsRow.length > 0 && (
+          <span data-testid="lamp-0" aria-label={berlin.secondsRow[0]}>
+            {/* optional visual */}
+          </span>
+        )}
+      </div>
+
+      {/* Five hours row */}
+      <div data-testid="five-hours-row">
+        <LampLine states={berlin.fiveHours} />
+      </div>
+
+      {/* Single hours row */}
+      <div data-testid="single-hours-row">
+        <LampLine states={berlin.oneHour} />
+      </div>
+
+      {/* Five minutes row */}
+      <div data-testid="five-minutes-row">
+        <LampLine states={berlin.fiveMinutes} />
+      </div>
+
+      {/* Single minutes row */}
+      <div data-testid="single-minutes-row">
+        <LampLine states={berlin.oneMinute} />
+      </div>
+    </div>
+  );
 }
--- a/src/setupTests.ts
+++ b/src/setupTests.ts
@@ -0,0 +1 @@
+import '@testing-library/jest-dom';
--- a/vite.config.ts
+++ b/vite.config.ts
@@ -1,7 +1,13 @@
+/// <reference types="vitest" />
 import { defineConfig } from "vite";
 import react from "@vitejs/plugin-react";

 // https://vite.dev/config/
 export default defineConfig({
  plugins: [react()],
+  test: {
+    globals: true,
+    environment: "jsdom",
+    setupFiles: "./src/setupTests.ts",
+  },
 });