diff tests/test-fix.t @ 42194:0da689a60163

fix: allow fixer tools to return metadata in addition to the file content

With this change, fixer tools can be configured to output a JSON object that
will be parsed and passed to hooks that can be used to print summaries of what
code was formatted or perform other post-fixing work.

The motivation for this change is to allow parallel executions of a
"meta-formatter" tool to report back statistics, which are then aggregated and
processed after all formatting has completed. Providing an extensible mechanism
inside fix.py is far simpler, and more portable, than trying to make a tool
like this communicate through some other channel.

Differential Revision: https://phab.mercurial-scm.org/D6167

--- a/tests/test-fix.t	Tue Apr 23 15:49:17 2019 -0400
+++ b/tests/test-fix.t	Thu Mar 21 18:32:45 2019 -0700
@@ -185,6 +185,36 @@
   tool may see different values for the arguments added by the :linerange
   suboption.
   
+  Each fixer tool is allowed to return some metadata in addition to the fixed
+  file content. The metadata must be placed before the file content on stdout,
+  separated from the file content by a zero byte. The metadata is parsed as a
+  JSON value (so, it should be UTF-8 encoded and contain no zero bytes). A fixer
+  tool is expected to produce this metadata encoding if and only if the
+  :metadata suboption is true:
+  
+    [fix]
+    tool:command = tool --prepend-json-metadata
+    tool:metadata = true
+  
+  The metadata values are passed to hooks, which can be used to print summaries
+  or perform other post-fixing work. The supported hooks are:
+  
+    "postfixfile"
+      Run once for each file in each revision where any fixer tools made changes
+      to the file content. Provides "$HG_REV" and "$HG_PATH" to identify the file,
+      and "$HG_METADATA" with a map of fixer names to metadata values from fixer
+      tools that affected the file. Fixer tools that didn't affect the file have a
+      valueof None. Only fixer tools that executed are present in the metadata.
+  
+    "postfix"
+      Run once after all files and revisions have been handled. Provides
+      "$HG_REPLACEMENTS" with information about what revisions were created and
+      made obsolete. Provides a boolean "$HG_WDIRWRITTEN" to indicate whether any
+      files in the working copy were updated. Provides a list "$HG_METADATA"
+      mapping fixer tool names to lists of metadata values returned from
+      executions that modified a file. This aggregates the same metadata
+      previously passed to the "postfixfile" hook.
+  
   list of commands:
   
    fix           rewrite file content in changesets or working directory