1 files changed, 28 insertions, 0 deletions
diff --git a/unit-tests/varmod-defined.mk b/unit-tests/varmod-defined.mk
new file mode 100644
index 000000000000..fa5bf5c2245c
--- /dev/null
+++ b/unit-tests/varmod-defined.mk
@@ -0,0 +1,28 @@
+# $NetBSD: varmod-defined.mk,v 1.3 2020/08/25 21:58:08 rillig Exp $
+#
+# Tests for the :D variable modifier, which returns the given string
+# if the variable is defined.  It is closely related to the :U modifier.
+
+DEF=	defined
+.undef UNDEF
+
+# Since DEF is defined, the value of the expression is "value", not
+# "defined".
+#
+.if ${DEF:Dvalue} != "value"
+.error
+.endif
+
+# Since UNDEF is not defined, the "value" is ignored.  Instead of leaving the
+# expression undefined, it is set to "", exactly to allow the expression to
+# be used in .if conditions.  In this place, other undefined expressions
+# would generate an error message.
+# XXX: Ideally the error message would be "undefined variable", but as of
+# 2020-08-25 it is "Malformed conditional".
+#
+.if ${UNDEF:Dvalue} != ""
+.error
+.endif
+
+all:
+	@:;