diff -r 513d68a90398 -r 3997edc4a86d tests/test-upgrade-repo.t
--- a/tests/test-upgrade-repo.t	Sun Dec 18 16:16:54 2016 -0800
+++ b/tests/test-upgrade-repo.t	Sun Dec 18 16:51:09 2016 -0800
@@ -49,3 +49,134 @@
   $ hg -R disallowaddedreq --config experimental.manifestv2=true --config experimental.treemanifest=true debugupgraderepo
   abort: cannot upgrade repository; do not support adding requirement: manifestv2, treemanifest
   [255]
+
+An upgrade of a repository created with recommended settings only suggests optimizations
+
+  $ hg init empty
+  $ cd empty
+  $ hg debugupgraderepo
+  (no feature deficiencies found in existing repository)
+  performing an upgrade with "--run" will make the following changes:
+  
+  requirements
+     preserved: dotencode, fncache, generaldelta, revlogv1, store
+  
+  additional optimizations are available by specifying "--optimize <name>":
+  
+  redeltaparent
+     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower
+  
+  redeltamultibase
+     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges
+  
+  redeltaall
+     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed
+  
+
+--optimize can be used to add optimizations
+
+  $ hg debugupgrade --optimize redeltaparent
+  (no feature deficiencies found in existing repository)
+  performing an upgrade with "--run" will make the following changes:
+  
+  requirements
+     preserved: dotencode, fncache, generaldelta, revlogv1, store
+  
+  redeltaparent
+     deltas within internal storage will choose a new base revision if needed
+  
+  additional optimizations are available by specifying "--optimize <name>":
+  
+  redeltamultibase
+     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges
+  
+  redeltaall
+     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed
+  
+
+Various sub-optimal detections work
+
+  $ cat > .hg/requires << EOF
+  > revlogv1
+  > store
+  > EOF
+
+  $ hg debugupgraderepo
+  repository lacks features recommended by current config options:
+  
+  fncache
+     long and reserved filenames may not work correctly; repository performance is sub-optimal
+  
+  dotencode
+     storage of filenames beginning with a period or space may not work correctly
+  
+  generaldelta
+     deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower
+  
+  
+  performing an upgrade with "--run" will make the following changes:
+  
+  requirements
+     preserved: revlogv1, store
+     added: dotencode, fncache, generaldelta
+  
+  fncache
+     repository will be more resilient to storing certain paths and performance of certain operations should be improved
+  
+  dotencode
+     repository will be better able to store files beginning with a space or period
+  
+  generaldelta
+     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster
+  
+  additional optimizations are available by specifying "--optimize <name>":
+  
+  redeltaparent
+     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower
+  
+  redeltamultibase
+     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges
+  
+  redeltaall
+     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed
+  
+
+  $ hg --config format.dotencode=false debugupgraderepo
+  repository lacks features recommended by current config options:
+  
+  fncache
+     long and reserved filenames may not work correctly; repository performance is sub-optimal
+  
+  generaldelta
+     deltas within internal storage are unable to choose optimal revisions; repository is larger and slower than it could be; interaction with other repositories may require extra network and CPU resources, making "hg push" and "hg pull" slower
+  
+  repository lacks features used by the default config options:
+  
+  dotencode
+     storage of filenames beginning with a period or space may not work correctly
+  
+  
+  performing an upgrade with "--run" will make the following changes:
+  
+  requirements
+     preserved: revlogv1, store
+     added: fncache, generaldelta
+  
+  fncache
+     repository will be more resilient to storing certain paths and performance of certain operations should be improved
+  
+  generaldelta
+     repository storage will be able to create optimal deltas; new repository data will be smaller and read times should decrease; interacting with other repositories using this storage model should require less network and CPU resources, making "hg push" and "hg pull" faster
+  
+  additional optimizations are available by specifying "--optimize <name>":
+  
+  redeltaparent
+     deltas within internal storage will be recalculated to choose an optimal base revision where this was not already done; the size of the repository may shrink and various operations may become faster; the first time this optimization is performed could slow down upgrade execution considerably; subsequent invocations should not run noticeably slower
+  
+  redeltamultibase
+     deltas within internal storage will be recalculated against multiple base revision and the smallest difference will be used; the size of the repository may shrink significantly when there are many merges; this optimization will slow down execution in proportion to the number of merges in the repository and the amount of files in the repository; this slow down should not be significant unless there are tens of thousands of files and thousands of merges
+  
+  redeltaall
+     deltas within internal storage will always be recalculated without reusing prior deltas; this will likely make execution run several times slower; this optimization is typically not needed
+  
+