diff -r d83e51654c8a -r fbc4eb8e2433 tests/test-hgrc.t
--- a/tests/test-hgrc.t	Sun Mar 26 21:33:37 2017 -0700
+++ b/tests/test-hgrc.t	Sun Mar 26 21:40:22 2017 -0700
@@ -176,6 +176,20 @@
   --debug: ui.debug=True
   --quiet: ui.quiet=False
 
+with environment variables
+
+  $ PAGER=p1 EDITOR=e1 VISUAL=e2 hg showconfig --debug
+  set config by: $EDITOR
+  set config by: $VISUAL
+  set config by: $PAGER
+  read config from: $TESTTMP/hgrc
+  repo: bundle.mainreporoot=$TESTTMP
+  $PAGER: pager.pager=p1
+  $VISUAL: ui.editor=e2
+  --verbose: ui.verbose=False
+  --debug: ui.debug=True
+  --quiet: ui.quiet=False
+
 plain mode with exceptions
 
   $ cat > plain.py <<EOF