pre-commit-no-snapshots.sh: improve SNAPSHOT check

ctrueden · ctrueden · commit 9d2802457b4a · 2013-06-10T14:10:24.000-05:00
The check now examines only the staged diff rather than the entire
working copy. So if you add a SNAPSHOT reference locally for development
purposes, but are not actually committing it, the commit will not fail.

Thanks to Barry DeZonia for the suggestion.
diff --git a/hooks/pre-commit-no-snapshots.sh b/hooks/pre-commit-no-snapshots.sh
@@ -1,9 +1,8 @@
 #!/bin/sh
 
-# Fail if any pom.xml files have more than one SNAPSHOT reference.
-# One reference to the parent is expected, but that's it!
-# Otherwise, builds will not be repeatable.
-if git grep -c SNAPSHOT $(git ls-files | grep pom.xml) | grep -v ':1$';
+# Fail if any new SNAPSHOT references are introduced into pom.xml files.
+# In general, SNAPSHOT references result in unstable/nonrepeatable builds.
+if git diff --staged -U0 $(git ls-files | grep pom.xml) | grep '^\+.*SNAPSHOT';
 then
   echo 'Potential SNAPSHOT references!'
   exit 1
