Fix minimum tick (and minimum tick value) precision (use decimals not floats)

Author: bryaningl3

docs/content/release_notes.md

@@ -1,5 +1,11 @@
 # Release Notes
 
+## 6.1.1
+**Bug Fixes**
+
+* Corrected precision issue exhibited by `UnitCode.getMinimumTick` function by switching internal calculations to use `Decimal` instances (instead of native floating point numbers).
+* Corrected precision issue exhibited by `UnitCode.getMinimumTickValue` function by switching internal calculations to use `Decimal` instances (instead of native floating point numbers).
+
 ## 6.1.0
 **New Features**
 

docs/content/releases/6.1.1.md

@@ -0,0 +1,4 @@
+**Bug Fixes**
+
+* Corrected precision issue exhibited by `UnitCode.getMinimumTick` function by switching internal calculations to use `Decimal` instances (instead of native floating point numbers).
+* Corrected precision issue exhibited by `UnitCode.getMinimumTickValue` function by switching internal calculations to use `Decimal` instances (instead of native floating point numbers).

docs/content/sdk/lib-utilities-data.md

@@ -166,7 +166,7 @@
         * [.getFractionFactor([special])](#UnitCodegetFractionFactor) ⇒ <code>Number</code> \| <code>undefined</code>
         * [.getFractionDigits([special])](#UnitCodegetFractionDigits) ⇒ <code>Number</code> \| <code>undefined</code>
         * [.getMinimumTick(tickIncrement)](#UnitCodegetMinimumTick) ⇒ <code>Number</code>
-        * [.getMinimumTickValue(tickIncrement, pointValue)](#UnitCodegetMinimumTickValue)
+        * [.getMinimumTickValue(tickIncrement, pointValue)](#UnitCodegetMinimumTickValue) ⇒ <code>Number</code>
     * _static_
         * [.parse(code)](#UnitCodeparse) ⇒ [<code>UnitCode</code>](#UnitCode) \| <code>null</code>
         * [.fromBaseCode(code)](#UnitCodefromBaseCode) ⇒ [<code>UnitCode</code>](#UnitCode) \| <code>null</code>
@@ -306,6 +306,7 @@
 > up by the minimum tick.
 
 **Kind**: instance method of [<code>UnitCode</code>](#UnitCode)  
+**Returns**: <code>Number</code>  
 **Access**: public  
 
 | Param | Type | Description |

lib/utilities/data/UnitCode.js

@@ -1,4 +1,5 @@
 const assert = require('@barchart/common-js/lang/assert'),
+	Decimal = require('@barchart/common-js/lang/Decimal'),
 	is = require('@barchart/common-js/lang/is');
 
 const Enum = require('@barchart/common-js/lang/Enum');
@@ -177,15 +178,20 @@ module.exports = (() => {
 		getMinimumTick(tickIncrement) {
 			assert.argumentIsValid(tickIncrement, 'tickIncrement', is.integer, 'must be an integer');
 
+			const one = new Decimal(1);
+			const ten = new Decimal(10);
+
 			let discretePrice;
 
 			if (this.supportsFractions) {
-				discretePrice = 1 / this._fractionFactor;
+				discretePrice = one.divide(this._fractionFactor);
 			} else {
-				discretePrice = 1 / (Math.pow(10, this._decimalDigits));
+				discretePrice = one.divide(ten.raise(this._decimalDigits));
 			}
 
-			return discretePrice * tickIncrement;
+			const minimumTick = discretePrice.multiply(tickIncrement);
+
+			return minimumTick.toFloat();
 		}
 
 		/**
@@ -201,7 +207,10 @@ module.exports = (() => {
 			assert.argumentIsValid(tickIncrement, 'tickIncrement', is.integer, 'must be an integer');
 			assert.argumentIsValid(pointValue, 'pointValue', is.number, 'must be a number');
 
-			return this.getMinimumTick(tickIncrement) * pointValue;
+			const minimumTick = new Decimal(this.getMinimumTick(tickIncrement));
+			const minimumTickValue = minimumTick.multiply(pointValue);
+
+			return minimumTickValue.toFloat();
 		}
 
 		toString() {

test/specs/utilities/data/UnitCodeSpec.js

@@ -985,7 +985,7 @@ describe('When calculating minimum ticks and minimum tick values', () => {
 		});
 	});
 
-	describe('For unit code "5" and with a tickIncrement of 1 and a pointValue of 1000 (e.g. t-notes)', () => {
+	describe('For unit code "5" and with a tickIncrement of 1 and a pointValue of 1,000 (e.g. t-notes)', () => {
 		let uc;
 
 		beforeEach(() => {
@@ -1000,5 +1000,21 @@ describe('When calculating minimum ticks and minimum tick values', () => {
 			expect(uc.getMinimumTickValue(1, 1000)).toEqual(15.625);
 		});
 	});
+
+	describe('For unit code "E" and with a tickIncrement of 10 and a pointValue of 500,000 (e.g. mexican pesos)', () => {
+		let uc;
+
+		beforeEach(() => {
+			uc = UnitCode.parse('E');
+		});
+
+		it('The minimum tick should be 0.015625', () => {
+			expect(uc.getMinimumTick(10)).toEqual(0.00001);
+		});
+
+		it('The minimum tick value should be 15.625', () => {
+			expect(uc.getMinimumTickValue(10, 500000)).toEqual(5);
+		});
+	});
 });