feat(datatype): introduce probability option to boolean (#1476)

3 files changed, 29 insertions, 6 deletions

diff --git a/src/modules/datatype/index.ts b/src/modules/datatype/index.ts
index d4fcbbd6..b40f2f43 100644
--- a/src/modules/datatype/index.ts
+++ b/src/modules/datatype/index.ts
@@ -192,13 +192,37 @@ export class DatatypeModule {
   /**
    * Returns the boolean value true or false.
    *
+   * **Note:**
+   * A probability of `0.75` results in `true` being returned `75%` of the calls; likewise `0.3` => `30%`.
+   * If the probability is `<= 0.0`, it will always return `false`.
+   * If the probability is `>= 1.0`, it will always return `true`.
+   * The probability is limited to two decimal places.
+   *
+   * @param options The optional options object or the probability (`[0.00, 1.00]`) of returning `true`. Defaults to `0.5`.
+   * @param options.probability The probability (`[0.00, 1.00]`) of returning `true`. Defaults to `0.5`.
+   *
    * @example
    * faker.datatype.boolean() // false
+   * faker.datatype.boolean(0.9) // true
+   * faker.datatype.boolean({ probability: 0.1 }) // false
    *
    * @since 5.5.0
    */
-  boolean(): boolean {
-    return !!this.number(1);
+  boolean(options: number | { probability?: number } = {}): boolean {
+    if (typeof options === 'number') {
+      options = {
+        probability: options,
+      };
+    }
+    const { probability = 0.5 } = options;
+    if (probability <= 0) {
+      return false;
+    }
+    if (probability >= 1) {
+      // This check is required to avoid returning false when float() returns 1
+      return true;
+    }
+    return this.float({ min: 0, max: 1 }) < probability;
   }
 
   /**
diff --git a/src/modules/finance/index.ts b/src/modules/finance/index.ts
index 3c60ec41..89b655bd 100644
--- a/src/modules/finance/index.ts
+++ b/src/modules/finance/index.ts
@@ -393,13 +393,13 @@ export class FinanceModule {
         if (bban.type === 'a') {
           s += this.faker.helpers.arrayElement(iban.alpha);
         } else if (bban.type === 'c') {
-          if (this.faker.datatype.number(100) < 80) {
+          if (this.faker.datatype.boolean(0.8)) {
             s += this.faker.datatype.number(9);
           } else {
             s += this.faker.helpers.arrayElement(iban.alpha);
           }
         } else {
-          if (c >= 3 && this.faker.datatype.number(100) < 30) {
+          if (c >= 3 && this.faker.datatype.boolean(0.3)) {
             if (this.faker.datatype.boolean()) {
               s += this.faker.helpers.arrayElement(iban.pattern100);
               c -= 2;
diff --git a/src/modules/helpers/index.ts b/src/modules/helpers/index.ts
index f3ad5a48..b8bbb725 100644
--- a/src/modules/helpers/index.ts
+++ b/src/modules/helpers/index.ts
@@ -354,8 +354,7 @@ export class HelpersModule {
     callback: () => T,
     options: { probability?: number } = {}
   ): T | undefined {
-    const { probability = 0.5 } = options;
-    if (this.faker.datatype.float({ min: 0, max: 1 }) < probability) {
+    if (this.faker.datatype.boolean(options)) {
       return callback();
     }
     return undefined;