test quick_cancel

Author: shashi

src/types.jl

@@ -858,6 +858,7 @@ function (::Type{Div{T}})(n, d, simplified=false; metadata=nothing) where {T}
     _iszero(n) && return zero(typeof(n))
     _isone(d) && return n
     d isa Number && _isone(-d) && return -1 * n
+    n isa Rat && d isa Rat && return n // d # maybe called by oblivious code in simplify
 
     # GCD coefficient upon construction
     rat, nc = ratcoeff(n)

test/polyform.jl

@@ -1,6 +1,8 @@
 using SymbolicUtils: PolyForm, Term, symtype
 using Test, SymbolicUtils
 
+include("utils.jl")
+
 @testset "div and polyform" begin
     @syms x y z
     @test repr(PolyForm(x-y)) == "x - y"
@@ -31,3 +33,14 @@ end
    #@test expand(identity(a * b) - b * a) == 0
     @test expand(a * b - b * a) == 0
 end
+
+@testset "simplify_fractions with quick-cancel" begin
+    @syms x y
+    @test simplify_fractions(x/2x) == 1//2
+    @test simplify_fractions(2x//x) == 2
+    @eqtest simplify_fractions((x+y) * (x-y) / (x+y)) == (x-y)
+    @eqtest simplify_fractions(x^3 * y / x) == y*x^2
+    @eqtest simplify_fractions(2x^3 * y / x) == 2y*x^2
+    @eqtest simplify_fractions(x / (3(x^3)*y)) == simplify_fractions(1/(3*(y*x^2)))
+    @eqtest simplify_fractions(2x / (3(x^3)*y)) == simplify_fractions(2/(3*(y*x^2)))
+end

test/runtests.jl

@@ -17,18 +17,10 @@ if v"1.6" ≤ VERSION < v"1.7-beta3.0"
 else
     @warn "Skipping doctests"
 end
-
-# == / != syntax is nice, let's use it in tests
-macro eqtest(expr)
-    @assert expr.head == :call && expr.args[1] in [:(==), :(!=)]
-    if expr.args[1] == :(==)
-        :(@test isequal($(expr.args[2]), $(expr.args[3])))
-    else
-        :(@test !isequal($(expr.args[2]), $(expr.args[3])))
-    end |> esc
-end
 SymbolicUtils.show_simplified[] = false
 
+include("utils.jl")
+
 if haskey(ENV, "SU_BENCHMARK_ONLY")
     include("benchmark.jl")
 else

test/utils.jl

@@ -0,0 +1,10 @@
+
+# == / != syntax is nice, let's use it in tests
+macro eqtest(expr)
+    @assert expr.head == :call && expr.args[1] in [:(==), :(!=)]
+    if expr.args[1] == :(==)
+        :(@test isequal($(expr.args[2]), $(expr.args[3])))
+    else
+        :(@test !isequal($(expr.args[2]), $(expr.args[3])))
+    end |> esc
+end