clearer testing of frame push/pop

lib/Global/Context.pm

@@ -2,6 +2,7 @@ use strict;
 use warnings;
 package Global::Context;
 
+use Carp ();
 use Global::Context::Env::Basic;
 use Global::Context::StackFrame::Trivial;
 
@@ -34,7 +35,7 @@ sub _export_context_glob {
 
 sub ctx_init {
   my ($arg) = @_;
-  confess("context has already been initialized") if $Object;
+  Carp::confess("context has already been initialized") if $Object;
 
   $Object = Global::Context::Env::Basic->new($arg)->with_pushed_frame(
     Global::Context::StackFrame::Trivial->new({

t/simple.t

@@ -7,6 +7,7 @@ use Global::Context::AuthToken::Basic;
 use Global::Context::Terminal::Basic;
 
 use Test::More;
+use Test::Fatal;
 
 ctx_init({
   terminal => Global::Context::Terminal::Basic->new({ uri => 'ip://1.2.3.4' }),
@@ -16,23 +17,37 @@ ctx_init({
   }),
 });
 
+like(
+  exception { ctx_init({}) },
+  qr/already/,
+  "we can't ctx_init twice",
+);
+
 {
   my @frames = map {; $_->as_string } $Context->stack->frames;
-  is(@frames, 1);
-  like($frames[0], qr/^context initialized/);
+  is(@frames, 1, "there's one frame, to start with");
+  like($frames[0], qr/^context initialized/, '...it is the ctx_init frame');
 }
 
 {
   local $Context = ctx_push("eat some pie");
   my @frames = map {; $_->as_string } $Context->stack->frames;
-  is(@frames, 1);
-  is($frames[0], 'eat some pie');
+  is(@frames, 1, 'after pushing a frame, the first is gone');
+  is($frames[0], 'eat some pie', '...only our new frame remains');
+
+  {
+    local $Context = ctx_push("drink some coffee");
+    my @frames = map {; $_->as_string } $Context->stack->frames;
+    is(@frames, 2, 'after pushing another frame, we have two frames');
+    is($frames[0], 'eat some pie',      '...0th frame is what we expect');
+    is($frames[1], 'drink some coffee', '...1st frame is what we expect');
+  }
 }
 
 {
   my @frames = map {; $_->as_string } $Context->stack->frames;
-  is(@frames, 1);
-  like($frames[0], qr/^context initialized/);
+  is(@frames, 1, 'when we leave the frame-pushed context, still 1 stack left');
+  like($frames[0], qr/^context initialized/, '...the ctx_init frame again');
 }
 
 done_testing;