Add a .gitignore file for the downloaded testdata.
diff --git a/.gitignore b/.gitignore
new file mode 100644
index 0000000..1b4ec93
--- /dev/null
+++ b/.gitignore
@@ -0,0 +1,11 @@
+testdata/alice29.txt
+testdata/asyoulik.txt
+testdata/fireworks.jpeg
+testdata/geo.protodata
+testdata/html
+testdata/html_x_4
+testdata/kppkn.gtb
+testdata/lcet10.txt
+testdata/paper-100k.pdf
+testdata/plrabn12.txt
+testdata/urls.10K
diff --git a/snappy_test.go b/snappy_test.go
index 99fa45f..6e1b847 100644
--- a/snappy_test.go
+++ b/snappy_test.go
@@ -465,6 +465,9 @@
// testFiles' values are copied directly from
// https://raw.githubusercontent.com/google/snappy/master/snappy_unittest.cc
// The label field is unused in snappy-go.
+//
+// If this list changes (due to the upstream C++ list changing), remember to
+// update the .gitignore file in this repository.
var testFiles = []struct {
label string
filename string
