Implement bonusAdd

2 files changed, 71 insertions, 1 deletions

diff --git a/__tests__/dice.test.js b/__tests__/dice.test.js
index 1be0744..6fb48a2 100644
--- a/__tests__/dice.test.js
+++ b/__tests__/dice.test.js
@@ -6,7 +6,8 @@ const {
   subtract,
   negative,
   explode,
-  keepHigh
+  keepHigh,
+  bonusAdd
 } = require('../src/dice.js')
 
 const defaultNumberRolls = 500
@@ -406,3 +407,63 @@ describe('keep', () => {
     testDie(die, basicDieTestSpecs(1, 20))
   })
 })
+
+describe('bonusAdd', () => {
+  describe('1d20+3', () => {
+    const die = bonusAdd(d(constant(1), constant(20)), constant(3))
+    testDie(die, {
+      diceCount: 1,
+      average: {
+        average: 13.5
+      },
+      variance: {
+        variance: 33.25
+      },
+      bounds: {
+        low: 4,
+        high: 23,
+        expectLow: true,
+        expectHigh: true
+      }
+    })
+  })
+
+  describe('3d4+1', () => {
+    const die = bonusAdd(d(constant(3), constant(4)), constant(1))
+    testDie(die, {
+      diceCount: 3,
+      average: {
+        average: 10.5
+      },
+      variance: {
+        variance: 3.75
+      },
+      bounds: {
+        low: 6,
+        high: 15,
+        expectLow: true,
+        expectHigh: true
+      }
+    })
+  })
+
+  describe('2d6+1d6', () => {
+    const die = bonusAdd(d(constant(2), constant(6)),
+      d(constant(1), constant(6)))
+    testDie(die, {
+      diceCount: 2,
+      average: {
+        average: 14
+      },
+      variance: {
+        variance: 11.67
+      },
+      bounds: {
+        low: 4,
+        high: 24,
+        expectLow: false,
+        expectHigh: false
+      }
+    })
+  })
+})
diff --git a/src/dice.js b/src/dice.js
index 5e3b975..14addd4 100644
--- a/src/dice.js
+++ b/src/dice.js
@@ -75,6 +75,14 @@ const keepHigh = (die1, die2) => {
   }
 }
 
+const bonusAdd = (die1, die2) => {
+  return () => {
+    return die1().map(die => {
+      return () => die() + roll(die2)
+    })
+  }
+}
+
 exports.pool = pool
 exports.roll = roll
 exports.constant = constant
@@ -84,3 +92,4 @@ exports.subtract = subtract
 exports.negative = negative
 exports.explode = explode
 exports.keepHigh = keepHigh
+exports.bonusAdd = bonusAdd