feat: add LaTeX representation for fractions and corresponding tests (#3434)

Author: orelbn

src/utils/latex.js

@@ -124,6 +124,7 @@ export const latexFunctions = {
   expm1: `\\left(e${latexOperators.pow}{\${args[0]}}-1\\right)`,
   fix: { 1: '\\mathrm{${name}}\\left(${args[0]}\\right)' },
   floor: { 1: '\\left\\lfloor${args[0]}\\right\\rfloor' },
+  fraction: { 2: '\\frac{${args[0]}}{${args[1]}}' },
   gcd: '\\gcd\\left(${args}\\right)',
   hypot: '\\hypot\\left(${args}\\right)',
   log: {

test/unit-tests/type/fraction/function/fraction.test.js

@@ -1,6 +1,6 @@
 import assert from 'assert'
-import math from '../../../../../src/defaultInstance.js'
 import Fraction from 'fraction.js'
+import math from '../../../../../src/defaultInstance.js'
 
 describe('fraction', function () {
   it('should create a fraction', function () {
@@ -81,6 +81,13 @@ describe('fraction', function () {
     assert.throws(function () { math.fraction(-Infinity) }, /Error: -Infinity cannot be represented as a fraction/)
     assert.throws(function () { math.fraction(NaN) }, /Error: NaN cannot be represented as a fraction/)
   })
+
+  it('should show a Latex Fraction as one over another', function () {
+    const node1 = math.parse('fraction(1,2)')
+    assert.strictEqual(node1.toTex(), '\\frac{1}{2}')
+    const node2 = math.parse('fraction(a,b)')
+    assert.strictEqual(node2.toTex(), '\\frac{ a}{\\mathrm{b}}')
+  })
 })
 
 function equalFraction (a, b) {