diff --git a/package.json b/package.json
index d202787411..a3258edfc3 100644
--- a/package.json
+++ b/package.json
@@ -28,7 +28,7 @@
   ],
   "scripts": {
     "test": "yarn test:mocha && yarn test:tsc && yarn test:lint && yarn test:prettier",
-    "test:coverage": "npx c8 yarn test:mocha",
+    "test:coverage": "c8 yarn test:mocha",
     "test:mocha": "mkdir -p test/output && TZ=America/Los_Angeles mocha 'test/**/*-test.*' 'test/plot.js'",
     "test:lint": "eslint src test",
     "test:prettier": "prettier --check src test",
@@ -58,6 +58,7 @@
     "@types/node": "^20.5.0",
     "@typescript-eslint/eslint-plugin": "^6.0.0",
     "@typescript-eslint/parser": "^6.0.0",
+    "c8": "^8.0.1",
     "canvas": "^2.0.0",
     "d3-geo-projection": "^4.0.0",
     "eslint": "^8.16.0",
diff --git a/yarn.lock b/yarn.lock
index 7670376b3c..e92c7b7522 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -143,6 +143,11 @@
   resolved "https://registry.yarnpkg.com/@babel/parser/-/parser-7.22.16.tgz#180aead7f247305cce6551bea2720934e2fa2c95"
   integrity sha512-+gPfKv8UWeKKeJTUxe59+OobVcrYHETCsORl61EmSkmgymguYk/X5bp7GuUIXaFsc6y++v8ZxPsLSSuujqDphA==
 
+"@bcoe/v8-coverage@^0.2.3":
+  version "0.2.3"
+  resolved "https://registry.yarnpkg.com/@bcoe/v8-coverage/-/v8-coverage-0.2.3.tgz#75a2e8b51cb758a7553d6804a5932d7aace75c39"
+  integrity sha512-0hYQ8SB4Db5zvZB4axdMHGwEaQjkZzFjQiN9LVYvIFB2nSUHW9tYpxWriPrWDASIxiaXax83REcLxuSdnGPZtw==
+
 "@docsearch/css@3.5.2", "@docsearch/css@^3.5.2":
   version "3.5.2"
   resolved "https://registry.yarnpkg.com/@docsearch/css/-/css-3.5.2.tgz#610f47b48814ca94041df969d9fcc47b91fc5aac"
@@ -335,6 +340,11 @@
   resolved "https://registry.yarnpkg.com/@humanwhocodes/object-schema/-/object-schema-1.2.1.tgz#b520529ec21d8e5945a1851dfd1c32e94e39ff45"
   integrity sha512-ZnQMnLV4e7hDlUvw8H+U8ASL02SS2Gn6+9Ac3wGGLIe7+je2AeAOxPY+izIPJDfFDb7eDjev0Us8MO1iFRN8hA==
 
+"@istanbuljs/schema@^0.1.2", "@istanbuljs/schema@^0.1.3":
+  version "0.1.3"
+  resolved "https://registry.yarnpkg.com/@istanbuljs/schema/-/schema-0.1.3.tgz#e45e384e4b8ec16bce2fd903af78450f6bf7ec98"
+  integrity sha512-ZXRY4jNvVgSVQ8DL3LTcakaAtXwTVUxE81hslsyD2AtoXW/wVob10HkOJ1X/pAlcI7D+2YoZKg5do8G/w6RYgA==
+
 "@jridgewell/gen-mapping@^0.3.0":
   version "0.3.3"
   resolved "https://registry.yarnpkg.com/@jridgewell/gen-mapping/-/gen-mapping-0.3.3.tgz#7e02e6eb5df901aaedb08514203b096614024098"
@@ -367,6 +377,14 @@
   resolved "https://registry.yarnpkg.com/@jridgewell/sourcemap-codec/-/sourcemap-codec-1.4.15.tgz#d7c6e6755c78567a951e04ab52ef0fd26de59f32"
   integrity sha512-eF2rxCRulEKXHTRiDrDy6erMYWqNw4LPdQ8UQA4huuxaQsVeRPFl2oM8oDGxMFhJUWZf9McpLtJasDDZb/Bpeg==
 
+"@jridgewell/trace-mapping@^0.3.12":
+  version "0.3.20"
+  resolved "https://registry.yarnpkg.com/@jridgewell/trace-mapping/-/trace-mapping-0.3.20.tgz#72e45707cf240fa6b081d0366f8265b0cd10197f"
+  integrity sha512-R8LcPeWZol2zR8mmH3JeKQ6QRCFb7XgUhV9ZlGhHLGyg4wpPiPZNQOOWhFZhxKw8u//yTbNGI42Bx/3paXEQ+Q==
+  dependencies:
+    "@jridgewell/resolve-uri" "^3.1.0"
+    "@jridgewell/sourcemap-codec" "^1.4.14"
+
 "@jridgewell/trace-mapping@^0.3.9":
   version "0.3.19"
   resolved "https://registry.yarnpkg.com/@jridgewell/trace-mapping/-/trace-mapping-0.3.19.tgz#f8a3249862f91be48d3127c3cfe992f79b4b8811"
@@ -724,6 +742,11 @@
   resolved "https://registry.yarnpkg.com/@types/geojson/-/geojson-7946.0.11.tgz#012c17cb2256ad8de78560da851ab914a7b9b40e"
   integrity sha512-L7A0AINMXQpVwxHJ4jxD6/XjZ4NDufaRlUJHjNIFKYUFBH1SvOW+neaqb0VTRSLW5suSrSu19ObFEFnfNcr+qg==
 
+"@types/istanbul-lib-coverage@^2.0.1":
+  version "2.0.6"
+  resolved "https://registry.yarnpkg.com/@types/istanbul-lib-coverage/-/istanbul-lib-coverage-2.0.6.tgz#7739c232a1fee9b4d3ce8985f314c0c6d33549d7"
+  integrity sha512-2QF/t/auWm0lsy8XtKVPG19v3sSOQlJe/YHZgfjb/KBBHOGSV+J2q/S671rcq9uTBrLAXmZpqJiaQbMT+zNU1w==
+
 "@types/json-schema@^7.0.12":
   version "7.0.13"
   resolved "https://registry.yarnpkg.com/@types/json-schema/-/json-schema-7.0.13.tgz#02c24f4363176d2d18fc8b70b9f3c54aba178a85"
@@ -1132,6 +1155,24 @@ builtin-modules@^3.3.0:
   resolved "https://registry.yarnpkg.com/builtin-modules/-/builtin-modules-3.3.0.tgz#cae62812b89801e9656336e46223e030386be7b6"
   integrity sha512-zhaCDicdLuWN5UbN5IMnFqNMhNfo919sH85y2/ea+5Yg9TsTkeZxpL+JLbp6cgYFS4sRLp3YV4S6yDuqVWHYOw==
 
+c8@^8.0.1:
+  version "8.0.1"
+  resolved "https://registry.yarnpkg.com/c8/-/c8-8.0.1.tgz#bafd60be680e66c5530ee69f621e45b1364af9fd"
+  integrity sha512-EINpopxZNH1mETuI0DzRA4MZpAUH+IFiRhnmFD3vFr3vdrgxqi3VfE3KL0AIL+zDq8rC9bZqwM/VDmmoe04y7w==
+  dependencies:
+    "@bcoe/v8-coverage" "^0.2.3"
+    "@istanbuljs/schema" "^0.1.3"
+    find-up "^5.0.0"
+    foreground-child "^2.0.0"
+    istanbul-lib-coverage "^3.2.0"
+    istanbul-lib-report "^3.0.1"
+    istanbul-reports "^3.1.6"
+    rimraf "^3.0.2"
+    test-exclude "^6.0.0"
+    v8-to-istanbul "^9.0.0"
+    yargs "^17.7.2"
+    yargs-parser "^21.1.1"
+
 callsites@^3.0.0:
   version "3.1.0"
   resolved "https://registry.yarnpkg.com/callsites/-/callsites-3.1.0.tgz#b3630abd8943432f54b3f0519238e33cd7df2f73"
@@ -1188,6 +1229,15 @@ cliui@^7.0.2:
     strip-ansi "^6.0.0"
     wrap-ansi "^7.0.0"
 
+cliui@^8.0.1:
+  version "8.0.1"
+  resolved "https://registry.yarnpkg.com/cliui/-/cliui-8.0.1.tgz#0c04b075db02cbfe60dc8e6cf2f5486b1a3608aa"
+  integrity sha512-BSeNnyus75C4//NQ9gQt1/csTXyo/8Sb+afLAkzAptFuMsod9HFokGNudZpi/oQV73hnVK+sR+5PVRMd+Dr7YQ==
+  dependencies:
+    string-width "^4.2.0"
+    strip-ansi "^6.0.1"
+    wrap-ansi "^7.0.0"
+
 code-block-writer@^12.0.0:
   version "12.0.0"
   resolved "https://registry.yarnpkg.com/code-block-writer/-/code-block-writer-12.0.0.tgz#4dd58946eb4234105aff7f0035977b2afdc2a770"
@@ -1255,7 +1305,12 @@ console-control-strings@^1.0.0, console-control-strings@^1.1.0:
   resolved "https://registry.yarnpkg.com/console-control-strings/-/console-control-strings-1.1.0.tgz#3d7cf4464db6446ea644bf4b39507f9851008e8e"
   integrity sha512-ty/fTekppD2fIwRvnZAVdeOiGd1c7YXEixbgJTNzqcxJWKQnjJ/V1bNEEE6hygpM3WjwHFUVK6HTjWSzV4a8sQ==
 
-cross-spawn@^7.0.2:
+convert-source-map@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/convert-source-map/-/convert-source-map-2.0.0.tgz#4b560f649fc4e918dd0ab75cf4961e8bc882d82a"
+  integrity sha512-Kvp459HrV2FEJ1CAsi1Ku+MY3kasH19TFykTz2xWmMeq6bk2NU3XXvfJ+Q61m0xktWwt+1HSYf3JZsTms3aRJg==
+
+cross-spawn@^7.0.0, cross-spawn@^7.0.2:
   version "7.0.3"
   resolved "https://registry.yarnpkg.com/cross-spawn/-/cross-spawn-7.0.3.tgz#f73a85b9d5d41d045551c177e2882d4ac85728a6"
   integrity sha512-iRDPJKUPVEND7dHPO8rkbOnPpyDygcDFtWjpeWNCgy8WP2rXcxXL8TskReQl6OrB2G7+UJrags1q15Fudc7G6w==
@@ -1863,6 +1918,14 @@ focus-trap@^7.5.2:
   dependencies:
     tabbable "^6.2.0"
 
+foreground-child@^2.0.0:
+  version "2.0.0"
+  resolved "https://registry.yarnpkg.com/foreground-child/-/foreground-child-2.0.0.tgz#71b32800c9f15aa8f2f83f4a6bd9bff35d861a53"
+  integrity sha512-dCIq9FpEcyQyXKCkyzmlPTFNgrCzPudOe+mhvJU5zAtlBnGVy2yKxtfsxK2tQBThwq225jcvBjpw1Gr40uzZCA==
+  dependencies:
+    cross-spawn "^7.0.0"
+    signal-exit "^3.0.2"
+
 form-data@^4.0.0:
   version "4.0.0"
   resolved "https://registry.yarnpkg.com/form-data/-/form-data-4.0.0.tgz#93919daeaf361ee529584b9b31664dc12c9fa452"
@@ -1947,7 +2010,7 @@ glob@7.2.0:
     once "^1.3.0"
     path-is-absolute "^1.0.0"
 
-glob@^7.1.3:
+glob@^7.1.3, glob@^7.1.4:
   version "7.2.3"
   resolved "https://registry.yarnpkg.com/glob/-/glob-7.2.3.tgz#b8df0fb802bbfa8e89bd1d938b4e16578ed44f2b"
   integrity sha512-nFR0zLpU2YCaRxwoCJvL6UvCH2JFyFVIvwTLsIf21AuHlMskA1hhTdk+LlYJtOlYt9v6dvszD2BGRqBL+iQK9Q==
@@ -2028,6 +2091,11 @@ html-encoding-sniffer@^3.0.0:
   dependencies:
     whatwg-encoding "^2.0.0"
 
+html-escaper@^2.0.0:
+  version "2.0.2"
+  resolved "https://registry.yarnpkg.com/html-escaper/-/html-escaper-2.0.2.tgz#dfd60027da36a36dfcbe236262c00a5822681453"
+  integrity sha512-H2iMtd0I4Mt5eYiapRdIDjp+XzelXQ0tFE4JS7YFwFevXXMmOp9myNrUvCg0D6ws8iqkRPBfKHgbwig1SmlLfg==
+
 http-proxy-agent@^5.0.0:
   version "5.0.0"
   resolved "https://registry.yarnpkg.com/http-proxy-agent/-/http-proxy-agent-5.0.0.tgz#5129800203520d434f142bc78ff3c170800f2b43"
@@ -2185,6 +2253,28 @@ isoformat@^0.2.0:
   resolved "https://registry.yarnpkg.com/isoformat/-/isoformat-0.2.1.tgz#2526344a4276a101b2881848dc337d1d2ae74494"
   integrity sha512-tFLRAygk9NqrRPhJSnNGh7g7oaVWDwR0wKh/GM2LgmPa50Eg4UfyaCO4I8k6EqJHl1/uh2RAD6g06n5ygEnrjQ==
 
+istanbul-lib-coverage@^3.0.0, istanbul-lib-coverage@^3.2.0:
+  version "3.2.2"
+  resolved "https://registry.yarnpkg.com/istanbul-lib-coverage/-/istanbul-lib-coverage-3.2.2.tgz#2d166c4b0644d43a39f04bf6c2edd1e585f31756"
+  integrity sha512-O8dpsF+r0WV/8MNRKfnmrtCWhuKjxrq2w+jpzBL5UZKTi2LeVWnWOmWRxFlesJONmc+wLAGvKQZEOanko0LFTg==
+
+istanbul-lib-report@^3.0.0, istanbul-lib-report@^3.0.1:
+  version "3.0.1"
+  resolved "https://registry.yarnpkg.com/istanbul-lib-report/-/istanbul-lib-report-3.0.1.tgz#908305bac9a5bd175ac6a74489eafd0fc2445a7d"
+  integrity sha512-GCfE1mtsHGOELCU8e/Z7YWzpmybrx/+dSTfLrvY8qRmaY6zXTKWn6WQIjaAFw069icm6GVMNkgu0NzI4iPZUNw==
+  dependencies:
+    istanbul-lib-coverage "^3.0.0"
+    make-dir "^4.0.0"
+    supports-color "^7.1.0"
+
+istanbul-reports@^3.1.6:
+  version "3.1.6"
+  resolved "https://registry.yarnpkg.com/istanbul-reports/-/istanbul-reports-3.1.6.tgz#2544bcab4768154281a2f0870471902704ccaa1a"
+  integrity sha512-TLgnMkKg3iTDsQ9PbPTdpfAK2DzjF9mqUG7RMgcQl8oFjad8ob4laGxv5XV5U9MAfx8D6tSJiUyuAwzLicaxlg==
+  dependencies:
+    html-escaper "^2.0.0"
+    istanbul-lib-report "^3.0.0"
+
 js-beautify@1:
   version "1.14.9"
   resolved "https://registry.yarnpkg.com/js-beautify/-/js-beautify-1.14.9.tgz#a5db728bc5a0d84d3b1a597c376b29bd4d39c8e5"
@@ -2314,6 +2404,13 @@ make-dir@^3.1.0:
   dependencies:
     semver "^6.0.0"
 
+make-dir@^4.0.0:
+  version "4.0.0"
+  resolved "https://registry.yarnpkg.com/make-dir/-/make-dir-4.0.0.tgz#c3c2307a771277cd9638305f915c29ae741b614e"
+  integrity sha512-hXdUTZYIVOt1Ex//jAQi+wTZZpUpwBj/0QsOzqegb3rGMMeJiSEu5xLHnYfBrRV4RH2+OCSOO95Is/7x1WJ4bw==
+  dependencies:
+    semver "^7.5.3"
+
 mark.js@8.11.1:
   version "8.11.1"
   resolved "https://registry.yarnpkg.com/mark.js/-/mark.js-8.11.1.tgz#180f1f9ebef8b0e638e4166ad52db879beb2ffc5"
@@ -2831,7 +2928,7 @@ shiki@^0.14.4:
     vscode-oniguruma "^1.7.0"
     vscode-textmate "^8.0.0"
 
-signal-exit@^3.0.0:
+signal-exit@^3.0.0, signal-exit@^3.0.2:
   version "3.0.7"
   resolved "https://registry.yarnpkg.com/signal-exit/-/signal-exit-3.0.7.tgz#a9a1767f8af84155114eaabd73f99273c8f59ad9"
   integrity sha512-wnD2ZE+l+SPC/uoS0vXeE9L1+0wuaMqKlfz9AMUo38JsyLSBWSFcHR1Rri62LZc12vLr1gb3jl7iwQhgwpAbGQ==
@@ -2957,6 +3054,15 @@ terser@^5.17.4:
     commander "^2.20.0"
     source-map-support "~0.5.20"
 
+test-exclude@^6.0.0:
+  version "6.0.0"
+  resolved "https://registry.yarnpkg.com/test-exclude/-/test-exclude-6.0.0.tgz#04a8698661d805ea6fa293b6cb9e63ac044ef15e"
+  integrity sha512-cAGWPIyOHU6zlmg88jwm7VRyXnMN7iV68OGAbYDk/Mh/xC/pzVPlQtY6ngoIH/5/tciuhGfvESU8GrHrcxD56w==
+  dependencies:
+    "@istanbuljs/schema" "^0.1.2"
+    glob "^7.1.4"
+    minimatch "^3.0.4"
+
 text-table@^0.2.0:
   version "0.2.0"
   resolved "https://registry.yarnpkg.com/text-table/-/text-table-0.2.0.tgz#7f5ee823ae805207c00af2df4a84ec3fcfa570b4"
@@ -3053,6 +3159,15 @@ util-deprecate@^1.0.1:
   resolved "https://registry.yarnpkg.com/util-deprecate/-/util-deprecate-1.0.2.tgz#450d4dc9fa70de732762fbd2d4a28981419a0ccf"
   integrity sha512-EPD5q1uXyFxJpCrLnCc1nHnq3gOa6DZBocAIiI2TaSCA7VCJ1UJDMagCzIkXNsUYfD1daK//LTEQ8xiIbrHtcw==
 
+v8-to-istanbul@^9.0.0:
+  version "9.1.3"
+  resolved "https://registry.yarnpkg.com/v8-to-istanbul/-/v8-to-istanbul-9.1.3.tgz#ea456604101cd18005ac2cae3cdd1aa058a6306b"
+  integrity sha512-9lDD+EVI2fjFsMWXc6dy5JJzBsVTcQ2fVkfBvncZ6xJWG9wtBhOldG+mHkSL0+V1K/xgZz0JDO5UT5hFwHUghg==
+  dependencies:
+    "@jridgewell/trace-mapping" "^0.3.12"
+    "@types/istanbul-lib-coverage" "^2.0.1"
+    convert-source-map "^2.0.0"
+
 vite@^4.4.9:
   version "4.4.9"
   resolved "https://registry.yarnpkg.com/vite/-/vite-4.4.9.tgz#1402423f1a2f8d66fd8d15e351127c7236d29d3d"
@@ -3220,6 +3335,11 @@ yargs-parser@^20.2.2:
   resolved "https://registry.yarnpkg.com/yargs-parser/-/yargs-parser-20.2.9.tgz#2eb7dc3b0289718fc295f362753845c41a0c94ee"
   integrity sha512-y11nGElTIV+CT3Zv9t7VKl+Q3hTQoT9a1Qzezhhl6Rp21gJ/IVTW7Z3y9EWXhuUBC2Shnf+DX0antecpAwSP8w==
 
+yargs-parser@^21.1.1:
+  version "21.1.1"
+  resolved "https://registry.yarnpkg.com/yargs-parser/-/yargs-parser-21.1.1.tgz#9096bceebf990d21bb31fa9516e0ede294a77d35"
+  integrity sha512-tVpsJW7DdjecAiFpbIB1e3qxIQsE6NoPc5/eTdrbbIC4h0LVsWhnoa3g+m2HclBIujHzsxZ4VJVA+GUuc2/LBw==
+
 yargs-unparser@2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/yargs-unparser/-/yargs-unparser-2.0.0.tgz#f131f9226911ae5d9ad38c432fe809366c2325eb"
@@ -3243,6 +3363,19 @@ yargs@16.2.0:
     y18n "^5.0.5"
     yargs-parser "^20.2.2"
 
+yargs@^17.7.2:
+  version "17.7.2"
+  resolved "https://registry.yarnpkg.com/yargs/-/yargs-17.7.2.tgz#991df39aca675a192b816e1e0363f9d75d2aa269"
+  integrity sha512-7dSzzRQ++CKnNI/krKnYRV7JKKPUXMEh61soaHKg9mrWEhzFWhFnxPxGl+69cD1Ou63C13NUPCnmIcrvqCuM6w==
+  dependencies:
+    cliui "^8.0.1"
+    escalade "^3.1.1"
+    get-caller-file "^2.0.5"
+    require-directory "^2.1.1"
+    string-width "^4.2.3"
+    y18n "^5.0.5"
+    yargs-parser "^21.1.1"
+
 yocto-queue@^0.1.0:
   version "0.1.0"
   resolved "https://registry.yarnpkg.com/yocto-queue/-/yocto-queue-0.1.0.tgz#0294eb3dee05028d31ee1a5fa2c556a6aaf10a1b"