Add theme helper function errors

__tests__/themeFunction.test.js

@@ -110,6 +110,127 @@ test('an unquoted list is valid as a default value', () => {
   })
 })
 
+test('a missing root theme value throws', () => {
+  const input = `
+    .heading { color: theme('colours.gray.100'); }
+  `
+
+  return expect(
+    run(input, {
+      theme: {
+        colors: {
+          yellow: '#f7cc50',
+        },
+      },
+    })
+  ).rejects.toThrowError(
+    `'colours.gray.100' does not exist in your theme config. Your theme has the following top-level keys: 'colors'`
+  )
+})
+
+test('a missing nested theme property throws', () => {
+  const input = `
+    .heading { color: theme('colors.red'); }
+  `
+
+  return expect(
+    run(input, {
+      theme: {
+        colors: {
+          blue: 'blue',
+          yellow: '#f7cc50',
+        },
+      },
+    })
+  ).rejects.toThrowError(
+    `'colors.red' does not exist in your theme config. 'colors' has the following valid keys: 'blue', 'yellow'`
+  )
+})
+
+test('a missing nested theme property with a close alternative throws with a suggestion', () => {
+  const input = `
+    .heading { color: theme('colors.yellw'); }
+  `
+
+  return expect(
+    run(input, {
+      theme: {
+        colors: {
+          yellow: '#f7cc50',
+        },
+      },
+    })
+  ).rejects.toThrowError(
+    `'colors.yellw' does not exist in your theme config. Did you mean 'colors.yellow'?`
+  )
+})
+
+test('a path through a non-object throws', () => {
+  const input = `
+    .heading { color: theme('colors.yellow.100'); }
+  `
+
+  return expect(
+    run(input, {
+      theme: {
+        colors: {
+          yellow: '#f7cc50',
+        },
+      },
+    })
+  ).rejects.toThrowError(
+    `'colors.yellow.100' does not exist in your theme config. 'colors.yellow' is not an object.`
+  )
+})
+
+test('a path which exists but is not a string throws', () => {
+  const input = `
+    .heading { color: theme('colors.yellow'); }
+  `
+
+  return expect(
+    run(input, {
+      theme: {
+        colors: {
+          yellow: Symbol(),
+        },
+      },
+    })
+  ).rejects.toThrowError(`'colors.yellow' was found but does not resolve to a string.`)
+})
+
+test('a path which exists but is invalid throws', () => {
+  const input = `
+    .heading { color: theme('colors'); }
+  `
+
+  return expect(
+    run(input, {
+      theme: {
+        colors: {},
+      },
+    })
+  ).rejects.toThrowError(`'colors' was found but does not resolve to a string.`)
+})
+
+test('a path which is an object throws with a suggested key', () => {
+  const input = `
+    .heading { color: theme('colors'); }
+  `
+
+  return expect(
+    run(input, {
+      theme: {
+        colors: {
+          yellow: '#f7cc50',
+        },
+      },
+    })
+  ).rejects.toThrowError(
+    `'colors' was found but does not resolve to a string. Did you mean something like 'colors.yellow'?`
+  )
+})
+
 test('array values are joined by default', () => {
   const input = `
     .heading { font-family: theme('fontFamily.sans'); }

package.json

@@ -58,6 +58,7 @@
     "chalk": "^4.1.0",
     "color": "^3.1.3",
     "detective": "^5.2.0",
+    "didyoumean": "^1.2.1",
     "fs-extra": "^9.0.1",
     "html-tags": "^3.1.0",
     "lodash": "^4.17.20",

src/lib/evaluateTailwindFunctions.js

@@ -1,5 +1,6 @@
 import _ from 'lodash'
 import functions from 'postcss-functions'
+import didYouMean from 'didyoumean'
 
 const themeTransforms = {
   fontSize(value) {
@@ -11,17 +12,124 @@ function defaultTransform(value) {
   return Array.isArray(value) ? value.join(', ') : value
 }
 
+function findClosestExistingPath(theme, path) {
+  const parts = _.toPath(path)
+  do {
+    parts.pop()
+
+    if (_.hasIn(theme, parts)) break
+  } while (parts.length)
+
+  return parts.length ? parts : undefined
+}
+
+function pathToString(path) {
+  if (typeof path === 'string') return path
+  return path.reduce((acc, cur, i) => {
+    if (cur.includes('.')) return `${acc}[${cur}]`
+    return i === 0 ? cur : `${acc}.${cur}`
+  }, '')
+}
+
+function list(items) {
+  return items.map((key) => `'${key}'`).join(', ')
+}
+
+function listKeys(obj) {
+  return list(Object.keys(obj))
+}
+
+function validatePath(config, path, defaultValue) {
+  const pathString = Array.isArray(path) ? pathToString(path) : _.trim(path, `'"`)
+  const pathSegments = Array.isArray(path) ? path : _.toPath(pathString)
+  const value = _.get(config.theme, pathString, defaultValue)
+
+  if (typeof value === 'undefined') {
+    let error = `'${pathString}' does not exist in your theme config.`
+    const parentSegments = pathSegments.slice(0, -1)
+    const parentValue = _.get(config.theme, parentSegments)
+
+    if (_.isObject(parentValue)) {
+      const validKeys = Object.keys(parentValue).filter(
+        (key) => validatePath(config, [...parentSegments, key]).isValid
+      )
+      const suggestion = didYouMean(_.last(pathSegments), validKeys)
+      if (suggestion) {
+        error += ` Did you mean '${pathToString([...parentSegments, suggestion])}'?`
+      } else if (validKeys.length > 0) {
+        error += ` '${pathToString(parentSegments)}' has the following valid keys: ${list(
+          validKeys
+        )}`
+      }
+    } else {
+      const closestPath = findClosestExistingPath(config.theme, pathString)
+      if (closestPath) {
+        const closestValue = _.get(config.theme, closestPath)
+        if (_.isObject(closestValue)) {
+          error += ` '${pathToString(closestPath)}' has the following keys: ${listKeys(
+            closestValue
+          )}`
+        } else {
+          error += ` '${pathToString(closestPath)}' is not an object.`
+        }
+      } else {
+        error += ` Your theme has the following top-level keys: ${listKeys(config.theme)}`
+      }
+    }
+
+    return {
+      isValid: false,
+      error,
+    }
+  }
+
+  if (
+    !(
+      typeof value === 'string' ||
+      typeof value === 'number' ||
+      value instanceof String ||
+      value instanceof Number ||
+      Array.isArray(value)
+    )
+  ) {
+    let error = `'${pathString}' was found but does not resolve to a string.`
+
+    if (_.isObject(value)) {
+      let validKeys = Object.keys(value).filter(
+        (key) => validatePath(config, [...pathSegments, key]).isValid
+      )
+      if (validKeys.length) {
+        error += ` Did you mean something like '${pathToString([...pathSegments, validKeys[0]])}'?`
+      }
+    }
+
+    return {
+      isValid: false,
+      error,
+    }
+  }
+
+  const [themeSection] = pathSegments
+
+  return {
+    isValid: true,
+    value: _.get(themeTransforms, themeSection, defaultTransform)(value),
+  }
+}
+
 export default function (config) {
-  return functions({
-    functions: {
-      theme: (path, ...defaultValue) => {
-        const trimmedPath = _.trim(path, `'"`)
-        return _.thru(_.get(config.theme, trimmedPath, defaultValue), (value) => {
-          const [themeSection] = trimmedPath.split('.')
-
-          return _.get(themeTransforms, themeSection, defaultTransform)(value)
-        })
+  return (root) =>
+    functions({
+      functions: {
+        theme: (path, ...defaultValue) => {
+          return _.thru(
+            validatePath(config, path, defaultValue.length ? defaultValue : undefined),
+            ({ isValid, value, error }) => {
+              if (isValid) return value
+              throw root.error(error)
+            }
+          )
+        },
       },
-    },
-  })
+    })(root)
 }

yarn.lock

@@ -2158,6 +2158,11 @@ detective@^5.2.0:
     defined "^1.0.0"
     minimist "^1.1.1"
 
+didyoumean@^1.2.1:
+  version "1.2.1"
+  resolved "https://registry.yarnpkg.com/didyoumean/-/didyoumean-1.2.1.tgz#e92edfdada6537d484d73c0172fd1eba0c4976ff"
+  integrity sha1-6S7f2tplN9SE1zwBcv0eugxJdv8=
+
 diff-sequences@^26.5.0:
   version "26.5.0"
   resolved "https://registry.yarnpkg.com/diff-sequences/-/diff-sequences-26.5.0.tgz#ef766cf09d43ed40406611f11c6d8d9dd8b2fefd"