From: Craig Small <csmall@dropbear.xyz>
Date: Wed, 1 Mar 2023 06:20:42 +0000 (+1100)
Subject: tests: Dont compare floats with ==
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=9b2f49166b73cef360cff0682459a0aa3e6ec8d8;p=procps-ng

tests: Dont compare floats with ==

Comparing floats with == is bad and I should feel bad I did this.
The problem is if something is close to, but not quite the exact
same fails tests.

I have used an epsilon of 1 because we don't care about accuracy,
just that the function works well enough.

References:
 issue procps-ng/procps#271
 https://how-to.fandom.com/wiki/Howto_compare_floating_point_numbers_in_the_C_programming_language

Signed-off-by: Craig Small <csmall@dropbear.xyz>
---

diff --git a/NEWS b/NEWS
index 4f11334a..bc293a3f 100644
--- a/NEWS
+++ b/NEWS
@@ -1,3 +1,7 @@
+procps-ng-NEXT
+---------------
+  * tests: dont compare floats with ==                     issue #271
+
 procps-ng-4.0.3
 ---------------
   * library
diff --git a/src/tests/test_strtod_nol.c b/src/tests/test_strtod_nol.c
index 0be798c2..8e5c5245 100644
--- a/src/tests/test_strtod_nol.c
+++ b/src/tests/test_strtod_nol.c
@@ -1,6 +1,7 @@
 
 #include <stdio.h>
 #include <stdlib.h>
+#include <math.h>
 #include "strutils.h"
 
 struct strtod_tests {
@@ -25,6 +26,11 @@ struct strtod_tests tests[] = {
     {NULL, 0.0}
 };
 
+#define EPSILON 1.0  // Really not trying for precision here
+int dequal(const double d1, const double d2)
+{
+    return fabs(d1-d2) < EPSILON;
+}
 
 
 int main(int argc, char *argv[])