Add regtest for \once \unset

diff --git a/input/regression/unset-once.ly b/input/regression/unset-once.ly
new file mode 100644 (file)
index 0000000..32fad55
--- /dev/null
+++ b/input/regression/unset-once.ly
@@ -0,0 +1,37 @@
+\version "2.17.15"
+
+\header {
+
+  texidoc = "@code{\\once \\unset} should change a context property
+value for just one timestep and then return to the previous value."
+
+}
+\relative c' {
+  \set fingeringOrientations = #'(left)
+  <e-1>1 |
+  \once \unset fingeringOrientations
+  <e-1>-"default" |
+  <e-1>-"left" |
+
+  \unset fingeringOrientations
+  <e-1>-"default" |
+  \once\unset fingeringOrientations
+  <e-1>-"default" |
+  <e-1>-"default" |
+  \set Score.fingeringOrientations = #'(right)
+  <e-1>-"right"
+  \once\unset fingeringOrientations
+  <e-1>-"right"
+  <e-1>-"right"
+  \once\set fingeringOrientations = #'(left)
+  <e-1>-"left"
+  <e-1>-"right"
+  \set fingeringOrientations = #'(left)
+  <e-1>-"left"
+  \once \unset fingeringOrientations
+  <e-1>-"right"
+  <e-1>-"left"
+  \unset fingeringOrientations
+  \set Score.fingeringOrientations = #'(up down)
+  <e-1>-"default"
+}