From 81d08e8ae8c1c74385943b2295861feb9679d243 Mon Sep 17 00:00:00 2001
From: SNAPKITTY COLLECTIVE <jessicalw34@gmail.com>
Date: Tue, 14 Jul 2026 14:53:53 -0600
Subject: [PATCH] feat(tests): add ANS double-number word test suite

---
 fth/double_test.fth | 48 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 48 insertions(+)
 create mode 100644 fth/double_test.fth

diff --git a/fth/double_test.fth b/fth/double_test.fth
new file mode 100644
index 0000000..a08f214
--- /dev/null
+++ b/fth/double_test.fth
@@ -0,0 +1,48 @@
+\ ANS Forth Double-Number Word Tests
+\ Tests for DOUBLE word set: 2CONSTANT 2VARIABLE 2! 2@ D+ D- DNEGATE
+\ Follows the style of fth/coretest.fth (JHU/APL test framework)
+
+include? testing fth/tester.fth
+
+TESTING DOUBLE NUMBER WORDS
+
+DECIMAL
+
+\ 2VARIABLE and 2!  2@
+2VARIABLE DVAR
+{ 5 6 DVAR 2! -> }
+{ DVAR 2@ -> 5 6 }
+
+\ 2CONSTANT
+2CONSTANT DCON 7 8
+{ DCON -> 7 8 }
+
+\ D+ (double-precision addition)
+{ 1 0 2 0 D+ -> 3 0 }
+{ -1 -1 1 0 D+ -> 0 0 }
+{ 0 1 0 1 D+ -> 0 2 }         \ test carry propagation
+
+\ D- (double-precision subtraction)
+{ 5 0 3 0 D- -> 2 0 }
+{ 3 0 5 0 D- -> -2 -1 }       \ negative result (2s complement)
+
+\ DNEGATE
+{ 1 0 DNEGATE -> -1 -1 }
+{ -1 -1 DNEGATE -> 1 0 }
+{ 0 0 DNEGATE -> 0 0 }
+
+\ D0= (double equal zero)
+{ 0 0 D0= -> TRUE }
+{ 1 0 D0= -> FALSE }
+{ 0 1 D0= -> FALSE }
+
+\ D= (double equality)
+{ 1 2 1 2 D= -> TRUE }
+{ 1 2 1 3 D= -> FALSE }
+
+\ D< (double less-than, signed)
+{ 0 0 1 0 D< -> TRUE }
+{ 1 0 0 0 D< -> FALSE }
+{ -1 -1 0 0 D< -> TRUE }
+
+CR .( Double-number tests complete.) CR