diff tests/test-extension.t @ 23150:aff73c777b0b

extdiff: allow a preconfigured merge-tool to be invoked

There are three ways to configure an extdiff tool:

    1) cmd.tool = (/path/to/exe optional)
    2) tool = (path/to/exe optional)
    3) tool = sometool someargs

Previously, if no executable is specified in the first two forms, the named tool
must be in $PATH, or the invocation fails.  Since the [merge-tools] section
already has the path to the diff executable, and/or the registry keys to find
the executable on Windows, reuse that configuration for forms 1 and 2 instead of
failing.  We already fallback to [diff-tools] and then [merge-tools] for program
arguments if they aren't specified in the [extdiff] section.

Since this additional lookup only occurs if an executable is not on the $PATH
for the named tool, this is backwards compatible.  For now, we assume the user
knows what he is doing if a path is provided.

This change allows a configuration file like this (assuming beyondcompare3 is
configured in merge-tools), instead of hardcoding system specific a path:

    [extdiff]
    beyondcompare3 =

--- a/tests/test-extension.t	Mon Nov 03 16:30:21 2014 -0600
+++ b/tests/test-extension.t	Fri Oct 31 21:34:55 2014 -0400
@@ -427,7 +427,9 @@
     # add new command called vdiff, runs kdiff3
     vdiff = kdiff3
   
-    # add new command called meld, runs meld (no need to name twice)
+    # add new command called meld, runs meld (no need to name twice).  If
+    # the meld executable is not available, the meld tool in [merge-tools]
+    # will be used, if available
     meld =
   
     # add new command called vimdiff, runs gvimdiff with DirDiff plugin