Fix make test-Test (JuliaLang#38406)

This testset would fail unless `--depwarn=yes` was set
(as it is in process 1). Just run it in its own process
that has the commandline flag set appropriately.

stdlib/Test/test/nothrow_testset.jl

@@ -0,0 +1,6 @@
+mutable struct NoThrowTestSet <: Test.AbstractTestSet
+ results::Vector
+ NoThrowTestSet(desc) = new([])
+end
+Test.record(ts::NoThrowTestSet, t::Test.Result) = (push!(ts.results, t); t)
+Test.finish(ts::NoThrowTestSet) = ts.results

stdlib/Test/test/runtests.jl

@@ -79,12 +79,8 @@ end
  "Thrown: ErrorException")
 end
 # Test printing of Fail results
-mutable struct NoThrowTestSet <: Test.AbstractTestSet
- results::Vector
- NoThrowTestSet(desc) = new([])
-end
-Test.record(ts::NoThrowTestSet, t::Test.Result) = (push!(ts.results, t); t)
-Test.finish(ts::NoThrowTestSet) = ts.results
+include("nothrow_testset.jl")
+
 let fails = @testset NoThrowTestSet begin
  # 1 - Fail - wrong exception
  @test_throws OverflowError error()
@@ -797,29 +793,30 @@ end
  @test startswith(fails[4].value, "ErrorException")
 end
 
-function newfunc()
- 42
-end
-@deprecate oldfunc newfunc
+let code = quote
+ function newfunc()
+ 42
+ end
+ @deprecate oldfunc newfunc
 
-@testset "@test_deprecated" begin
- @test_deprecated oldfunc()
+ @testset "@test_deprecated" begin
+ @test_deprecated oldfunc()
+ @test Base.JLOptions().depwarn == 1
 
- # Expression passthrough
- if Base.JLOptions().depwarn != 2
- @test (@test_deprecated oldfunc()) == 42
+ @test (@test_deprecated oldfunc()) == 42
 
- fails = @testset NoThrowTestSet "check that @test_deprecated detects bad input" begin
- @test_deprecated newfunc()
- @test_deprecated r"Not found in message" oldfunc()
+ fails = @testset NoThrowTestSet "check that @test_deprecated detects bad input" begin
+ @test_deprecated newfunc()
+ @test_deprecated r"Not found in message" oldfunc()
+ end
+ @test length(fails) == 2
+ @test fails[1] isa Test.LogTestFailure
+ @test fails[2] isa Test.LogTestFailure
  end
- @test length(fails) == 2
- @test fails[1] isa Test.LogTestFailure
- @test fails[2] isa Test.LogTestFailure
- else
- @warn """Omitting `@test_deprecated` tests which can't yet
- be tested in --depwarn=error mode"""
  end
+ incl = "include($(repr(joinpath(@__DIR__, "nothrow_testset.jl"))))"
+ cmd = `$(Base.julia_cmd()) --startup-file=no --depwarn=yes -e 'using Test' -e $incl -e $code`
+ @test success(pipeline(cmd))
 end
 
 @testset "@testset preserves GLOBAL_RNG's state, and re-seeds it" begin