feat: lorem null response fix (#1407)

src/modules/lorem/index.ts

@@ -1,4 +1,5 @@
 import type { Faker } from '../..';
+import { filterWordListByLength } from '../word/filterWordListByLength';
 
 /**
  * Module to generate random texts and words.
@@ -17,24 +18,43 @@ export class LoremModule {
   /**
    * Generates a word of a specified length.
    *
-   * @param length length of the word that should be returned. Defaults to a random length.
+   * @param options The expected length of the word or the options to use.
+   * @param options.length The expected length of the word.
+   * @param options.strategy The strategy to apply when no words with a matching length are found.
+   *
+   * Available error handling strategies:
+   *
+   * - `fail`: Throws an error if no words with the given length are found.
+   * - `shortest`: Returns any of the shortest words.
+   * - `closest`: Returns any of the words closest to the given length.
+   * - `longest`: Returns any of the longest words.
+   * - `any-length`: Returns a word with any length.
+   *
+   * Defaults to `'any-length'`.
    *
    * @example
    * faker.lorem.word() // 'temporibus'
    * faker.lorem.word(5) // 'velit'
+   * faker.lorem.word({ strategy: 'shortest' }) // 'a'
+   * faker.lorem.word({ length: { min: 5, max: 7 }, strategy: "fail" }) // 'quaerat'
    *
    * @since 3.1.0
    */
-  word(length?: number): string {
-    const hasRightLength = (word: string) => word.length === length;
-    let properLengthWords: readonly string[];
-    if (length == null) {
-      properLengthWords = this.faker.definitions.lorem.words;
-    } else {
-      properLengthWords =
-        this.faker.definitions.lorem.words.filter(hasRightLength);
-    }
-    return this.faker.helpers.arrayElement(properLengthWords);
+  word(
+    options:
+      | number
+      | {
+          length?: number | { min: number; max: number };
+          strategy?: 'fail' | 'closest' | 'shortest' | 'longest' | 'any-length';
+        } = {}
+  ): string {
+    const opts = typeof options === 'number' ? { length: options } : options;
+    return this.faker.helpers.arrayElement(
+      filterWordListByLength({
+        ...opts,
+        wordList: this.faker.definitions.lorem.words,
+      })
+    );
   }
 
   /**

src/modules/word/filterWordListByLength.ts

@@ -0,0 +1,98 @@
+import { FakerError } from '../../errors/faker-error';
+
+/**
+ * The error handling strategies for the `filterWordListByLength` function.
+ *
+ * Always returns a new array.
+ */
+const STRATEGIES = {
+  fail: () => {
+    throw new FakerError('No words found that match the given length.');
+  },
+  closest: (
+    wordList: string[],
+    length: { min: number; max: number }
+  ): string[] => {
+    const wordsByLength = wordList.reduce((data, word) => {
+      (data[word.length] = data[word.length] ?? []).push(word);
+      return data;
+    }, {} as Record<number, string[]>);
+
+    const lengths = Object.keys(wordsByLength).map(Number);
+    const min = Math.min(...lengths);
+    const max = Math.max(...lengths);
+
+    const closestOffset = Math.min(length.min - min, max - length.max);
+
+    return wordList.filter(
+      (word) =>
+        word.length === length.min - closestOffset ||
+        word.length === length.max + closestOffset
+    );
+  },
+  shortest: (wordList: string[]): string[] => {
+    const minLength = Math.min(...wordList.map((word) => word.length));
+    return wordList.filter((word) => word.length === minLength);
+  },
+  longest: (wordList: string[]): string[] => {
+    const maxLength = Math.max(...wordList.map((word) => word.length));
+    return wordList.filter((word) => word.length === maxLength);
+  },
+  'any-length': (wordList: string[]): string[] => {
+    return [...wordList];
+  },
+} as const; /*
+satisfies Record<
+string, // Parameters<filterWordListByLength>[0]['strategy']
+(wordList: string[], length: { min: number; max: number }) => string[]
+>;
+*/
+
+/**
+ * Filters a string array for values with a matching length.
+ * If length is not provided or no values with a matching length are found,
+ * then the result will be determined using the given error handling strategy.
+ *
+ * @param options The options to provide.
+ * @param options.wordList A list of words to filter.
+ * @param options.length The exact or the range of lengths the words should have.
+ * @param options.strategy The strategy to apply when no words with a matching length are found. Defaults to 'any-length'.
+ *
+ * Available error handling strategies:
+ *
+ * - `fail`: Throws an error if no words with the given length are found.
+ * - `shortest`: Returns any of the shortest words.
+ * - `closest`: Returns any of the words closest to the given length.
+ * - `longest`: Returns any of the longest words.
+ * - `any-length`: Returns a copy of the original word list.
+ */
+export function filterWordListByLength(options: {
+  wordList: string[];
+  length?: number | { min: number; max: number };
+  strategy?: 'fail' | 'closest' | 'shortest' | 'longest' | 'any-length';
+}): string[] {
+  const { wordList, length, strategy = 'any-length' } = options;
+
+  if (length) {
+    const filter: (word: string) => boolean =
+      typeof length === 'number'
+        ? (word) => word.length === length
+        : (word) => word.length >= length.min && word.length <= length.max;
+
+    const wordListWithLengthFilter = wordList.filter(filter);
+
+    if (wordListWithLengthFilter.length > 0) {
+      return wordListWithLengthFilter;
+    }
+
+    if (typeof length === 'number') {
+      return STRATEGIES[strategy](wordList, { min: length, max: length });
+    } else {
+      return STRATEGIES[strategy](wordList, length);
+    }
+  } else if (strategy === 'shortest' || strategy === 'longest') {
+    return STRATEGIES[strategy](wordList);
+  } else {
+    return [...wordList];
+  }
+}