1 files changed, 31 insertions, 13 deletions
diff --git a/unit-tests/directive-ifdef.mk b/unit-tests/directive-ifdef.mk
index 12f3648e8b2c..8a60fb4a2669 100644
--- a/unit-tests/directive-ifdef.mk
+++ b/unit-tests/directive-ifdef.mk
@@ -1,33 +1,51 @@
-# $NetBSD: directive-ifdef.mk,v 1.4 2021/01/21 23:03:41 rillig Exp $
+# $NetBSD: directive-ifdef.mk,v 1.5 2022/01/23 21:48:59 rillig Exp $
 #
-# Tests for the .ifdef directive.
-
-# TODO: Implementation
+# Tests for the .ifdef directive, which evaluates bare words by calling
+# 'defined(word)'.
 
 DEFINED=	defined
 
+# There is no variable named 'UNDEF', therefore the condition evaluates to
+# false.
+.ifdef UNDEF
+.  error
+.endif
+
+# There is a variable named 'DEFINED', so the condition evaluates to true.
+.ifdef DEFINED
+.else
+.  error
+.endif
+
+# Since a bare word is an abbreviation for 'defined(word)', these can be
+# used to construct complex conditions.
+.ifdef UNDEF && DEFINED
+.  error
+.endif
+.ifdef UNDEF || DEFINED
+.else
+.  error
+.endif
+
 # It looks redundant to have a call to defined() in an .ifdef, but it's
-# possible.  The .ifdef only affects plain symbols, not function calls.
+# possible.  The '.ifdef' only affects bare words, not function calls.
 .ifdef defined(DEFINED)
-.  info Function calls in .ifdef are possible.
 .else
 .  error
 .endif
 
-# String literals are handled the same in all variants of the .if directive.
-# They evaluate to true if they are not empty.  Whitespace counts as non-empty
-# as well.
+# String literals are handled the same in all variants of the '.if' directive,
+# they evaluate to true if they are not empty, therefore this particular
+# example looks confusing and is thus not found in practice.
 .ifdef ""
 .  error
 .else
-.  info String literals are tested for emptiness.
 .endif
 
+# Whitespace counts as non-empty as well.
 .ifdef " "
-.  info String literals are tested for emptiness.  Whitespace is non-empty.
 .else
 .  error
 .endif
 
-all:
-	@:;
+all: .PHONY