TST more combinatorics tests

test/combinatorics.jl

@@ -1,20 +1,37 @@
-@test factorial(7) == 5040
-@test factorial(7,3) == 7*6*5*4
 @test binomial(5,-1) == 0
 @test binomial(5,10) == 0
 @test binomial(5,3) == 10
+@test binomial(2,1) == 2
+@test binomial(1,2) == 0
+@test binomial(-2,1) == -2
+@test binomial(2,-1) == 0
+
+#Issue 6154
+@test binomial(int32(34), int32(15)) == binomial(BigInt(34), BigInt(15)) == 1855967520
+@test binomial(int64(67), int64(29)) == binomial(BigInt(67), BigInt(29)) == 7886597962249166160
+@test binomial(int128(131), int128(62)) == binomial(BigInt(131), BigInt(62)) == 157311720980559117816198361912717812000
+@test_throws InexactError binomial(int64(67), int64(30))
+
 p = shuffle([1:1000])
 @test isperm(p)
 @test all(invperm(invperm(p)) .== p)
+
 push!(p, 1)
 @test !isperm(p)
+
 a = randcycle(10)
 @test ipermute!(permute!([1:10], a),a) == [1:10]
+
+@test collect(combinations("abc",3)) == ["abc"]
 @test collect(combinations("abc",2)) == ["ab","ac","bc"]
+@test collect(combinations("abc",1)) == ["a","b","c"]
+@test collect(combinations("abc",0)) == [""]
 @test collect(permutations("abc")) == ["abc","acb","bac","bca","cab","cba"]
+
 @test collect(filter(x->(iseven(x[1])),permutations([1,2,3]))) == Any[[2,1,3],[2,3,1]]
 @test collect(filter(x->(iseven(x[3])),permutations([1,2,3]))) == Any[[1,3,2],[3,1,2]]
 @test collect(filter(x->(iseven(x[1])),combinations([1,2,3],2))) == Any[[2,3]]
+
 @test collect(partitions(4)) ==  Any[[4], [3,1], [2,2], [2,1,1], [1,1,1,1]]
 @test collect(partitions(8,3)) == Any[[6,1,1], [5,2,1], [4,3,1], [4,2,2], [3,3,2]]
 @test collect(partitions(8, 1)) == Any[[8]]
@@ -36,18 +53,16 @@ for n = 0:7, k = 1:factorial(n)
     @test nthperm(p) == k
 end
 
-#Issue 6154
-@test binomial(int32(34), int32(15)) == binomial(BigInt(34), BigInt(15)) == 1855967520
-@test binomial(int64(67), int64(29)) == binomial(BigInt(67), BigInt(29)) == 7886597962249166160
-@test binomial(int128(131), int128(62)) == binomial(BigInt(131), BigInt(62)) == 157311720980559117816198361912717812000
-
-# issue #6579
+@test factorial(7) == 5040
+@test factorial(7,3) == 7*6*5*4
 @test factorial(0) == 1
+@test_throws DomainError factorial(-1)
+
 @test factorial(int64(20)) == 2432902008176640000
+# issue #6579
 @test_throws OverflowError factorial(int64(21))
-@test_throws DomainError factorial(-1)
 @test typeof(factorial(int8(2))) == typeof(factorial(int8(1)))
 if Int === Int32
-@test factorial(int32(12)) === int32(479001600)
-@test_throws OverflowError factorial(int32(13))
+    @test factorial(int32(12)) === int32(479001600)
+    @test_throws OverflowError factorial(int32(13))
 end