test: Test compares against NaN

Make sure that floats compare correctly with NaN

Signed-off-by: Keith Packard <keithp@keithp.com>

test/Makefile

@@ -42,6 +42,7 @@ SUCCESS_TESTS = \
 	pass-if.py \
 	pass-int.py \
 	pass-math.py \
+	pass-nan.py \
 	pass-op.py \
 	pass-random.py \
 	pass-range.py \

test/pass-nan.py

@@ -0,0 +1,41 @@
+#!/usr/bin/python3
+#
+# Copyright © 2021 Keith Packard <keithp@keithp.com>
+#
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful, but
+# WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+# General Public License for more details.
+#
+
+#
+# Make sure that when nan is compared with any number
+# the result is false for any op other than !=
+#
+
+nan = float("nan")
+inf = float("inf")
+
+for x in (nan, -nan, -inf, inf, -1, 0, 1):
+    assert not (nan == x)
+    assert not (x == nan)
+
+    assert nan != x
+    assert x != nan
+
+    assert not (nan > x)
+    assert not (x > nan)
+
+    assert not (nan < x)
+    assert not (x < nan)
+
+    assert not (nan >= x)
+    assert not (x >= nan)
+
+    assert not (nan <= x)
+    assert not (x <= nan)