Test: make Error constructor more robust to broken objects (JuliaLang…

…#42850)

stdlib/Test/src/Test.jl

@@ -180,13 +180,32 @@ struct Error <: Result
  bt = scrub_exc_stack(bt)
  end
  if test_type === :test_error || test_type === :nontest_error
- bt_str = sprint(Base.show_exception_stack, bt; context=stdout)
+ bt_str = try # try the latest world for this, since we might have eval'd new code for show
+ Base.invokelatest(sprint, Base.show_exception_stack, bt; context=stdout)
+ catch ex
+ "#=ERROR showing exception stack=# " *
+ try
+ sprint(Base.showerror, ex, catch_backtrace(); context=stdout)
+ catch
+ "of type " * string(typeof(ex))
+ end
+ end
  else
  bt_str = ""
  end
+ value = try # try the latest world for this, since we might have eval'd new code for show
+ Base.invokelatest(sprint, show, value, context = :limit => true)
+ catch ex
+ "#=ERROR showing error of type " * string(typeof(value)) * "=# " *
+ try
+ sprint(Base.showerror, ex, catch_backtrace(); context=stdout)
+ catch
+ "of type " * string(typeof(ex))
+ end
+ end
  return new(test_type,
  string(orig_expr),
- sprint(show, value, context = :limit => true),
+ value,
  bt_str,
  source)
  end

stdlib/Test/test/runtests.jl

@@ -300,11 +300,17 @@ let fails = @testset NoThrowTestSet begin
 
 end
 
+struct BadError <: Exception end
+Base.show(io::IO, ::BadError) = throw("I am a bad error")
 let errors = @testset NoThrowTestSet begin
  # 1 - Error - unexpected pass
  @test_broken true
  # 2 - Error - converting a call into a comparison
  @test ==(1, 1:2...)
+ # 3 - Error - objects with broken show
+ @test throw(BadError())
+ @test BadError()
+ throw(BadError())
  end
 
  for err in errors
@@ -320,6 +326,18 @@ let errors = @testset NoThrowTestSet begin
  @test occursin("Expression: ==(1, 1:2...)", str)
  @test occursin("MethodError: no method matching ==(::$Int, ::$Int, ::$Int)", str)
  end
+
+ let str = sprint(show, errors[3])
+ @test occursin("Expression: throw(BadError())\n #=ERROR showing exception stack=# \"I am a bad error\"\n Stacktrace:\n", str)
+ end
+
+ let str = sprint(show, errors[4])
+ @test occursin("Expression: BadError()\n Value: #=ERROR showing error of type $BadError=# \"I am a bad error\"\nStacktrace:\n", str)
+ end
+
+ let str = sprint(show, errors[5])
+ @test occursin("Got exception outside of a @test\n #=ERROR showing exception stack=# \"I am a bad error\"\n Stacktrace:\n", str)
+ end
 end
 
 let retval_tests = @testset NoThrowTestSet begin