Julia: Lack of type info when `isa` test fails

[nickrobinson251]

When @test x isa Thing fails it can show output that _looks_ like it should have passed, because it does not print the type of x.

Here's an example [using Julia 1.1.0]:

julia> using Distributions, LinearAlgebra, Test

julia> covt(x) = cov(x)'   # means we will get an `Adjoint` 
covt (generic function with 1 method)

julia> z = MvNormal(2, 1);

julia> @test covt(z) isa Matrix
Test Failed at REPL[12]:1
  Expression: covt(z) isa Matrix
   Evaluated: [1.0 0.0; 0.0 1.0] isa Array{T,2} where T
ERROR: There was an error during testing
````
This is confusing because if you copy and paste the "Evaluated: ..." code in to a test it will pass
```julia
julia> @test [1.0 0.0; 0.0 1.0] isa Array{T,2} where T
Test Passed

It may be more informative if the output of the failed test was more like

julia> @test covt(z) isa Matrix
Test Failed at REPL[12]:1
  Expression: covt(z) isa Matrix
   Evaluated: Adjoint{Float64,Array{Float64,2}} <: Array{T,2} where T
ERROR: There was an error during testing

(where Evaluiated: could show <: rather than isa, since (Array{Float64,2} isa Array{T,2} where T) == false).

[nickrobinson251]

Related https://github.com/JuliaLang/julia/pull/30721 -- but I don't think this exact issue was addressed? Not sure. I see this issue got closed https://github.com/JuliaLang/julia/issues/26882

[StefanKarpinski]

Yes, seems like it would be better to print the type gotten than the value gotten even.

[apieum]

Sorry, for my mistakes, messages and tests were false, if it's OK I can do this:
(1)

julia> @test covt(z) isa Matrix
Test Failed at REPL[12]:1
  Expression: covt(z) isa Matrix
   Evaluated: [1.0 0.0; 0.0 1.0]::Adjoint{Float64,Array{Float64,2}} isa Array{T,2} where T
ERROR: There was an error during testing

Or (2)

julia> @test covt(z) isa Matrix
Test Failed at REPL[12]:1
  Expression: covt(z) isa Matrix
   Evaluated: Adjoint{Float64,Array{Float64,2}}([1.0 0.0; 0.0 1.0]) isa Array{T,2} where T
ERROR: There was an error during testing

if it makes sense.

[omus]

We may just want to print the type as the values in this case are not providing useful and are most likely obfuscating the reason for the test failure.