[Distributed] add some unit tests for managers.jl (JuliaLang/julia#34963)

It finds a bug.

Author: ssikdar1

src/managers.jl

@@ -195,7 +195,7 @@ function parse_machine(machine::AbstractString)
     if machine[begin] == '['  # ipv6 bracket notation (RFC 2732)
         ipv6_end = findlast(']', machine)
         if ipv6_end === nothing
-            throw(ArgumentError("invalid machine definition format string: invalid port format \"$machine_def\""))
+            throw(ArgumentError("invalid machine definition format string: invalid port format \"$machine\""))
         end
         hoststr = machine[begin+1 : prevind(machine,ipv6_end)]
         machine_def = split(machine[ipv6_end : end] , ':')

test/managers.jl

@@ -13,9 +13,13 @@ using Distributed: parse_machine, SSHManager, LocalManager
 @test parse_machine("127.0.0.1:90") == ("127.0.0.1", 90)
 @test parse_machine("127.0.0.1:1") == ("127.0.0.1", 1)
 @test parse_machine("127.0.0.1:65535") == ("127.0.0.1", 65535)
+
 @test_throws ArgumentError parse_machine("127.0.0.1:-1")
 @test_throws ArgumentError parse_machine("127.0.0.1:0")
 @test_throws ArgumentError parse_machine("127.0.0.1:65536")
+@test_throws ArgumentError parse_machine("[2001:db8::1]:443:888")
+@test_throws ArgumentError parse_machine("[2001:db8::1")
+@test_throws ArgumentError parse_machine("[2001:db8::1]:aaa")
 
 @test occursin(r"^SSHManager\(machines=.*\)$",
                sprint((t,x) -> show(t, "text/plain", x), SSHManager("127.0.0.1")))