[cairo] [PATCH 3/3] README : Update README file related to usage of FORMAT make variable

[Ravi Nanjundappa]

Signed-off-by: Ravi Nanjundappa <nravi.n at samsung.com>
---
 test/README |   10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/test/README b/test/README
index e8e7189..c1ff19d 100644
--- a/test/README
+++ b/test/README
@@ -49,6 +49,16 @@ should be a space-separated list of tests to run.  For example:
 
   CAIRO_TESTS="zero-alpha" make test TARGETS=image,ps
 
+To limit the content formats that the tests are run against, use the
+FORMAT make variable, that can also be passed to make.
+It should contain a (space-, comma-, etc-separated) list of content formats to test.
+To limit the tests run, use the CAIRO_TESTS environment variable, which
+should be a space-separated list of tests to run and also to limit the
+backends, use TARGETS environment variable, which should be a space-, comma-,
+etc-separated lists of backends.  For example:
+
+  CAIRO_TESTS="zero-alpha" make test TARGETS=image,ps FORMAT="rgb,rgba"
+
 Another very handy mechanism when trying to fix bugs is:
 
   make retest
-- 
1.7.9.5