SL-18837: When llrand_test.cpp fails, display the failing value.

It's frustrating and unactionable to have a failing test report merely that
the random value was greater than the specified high end. Okay, so what was
the value? If it's supposed to be less than the high end, did it happen to be
equal? Or was it garbage? We can't reproduce the failure by rerunning!

The new ensure_in_exc_range(), ensure_in_inc_range() mechanism is somewhat
complex because exactly one test allows equality with the high end of the
expected range, where the rest mandate that the function return less than the
high end. If that's a bug in the test -- if every llrand function is supposed
to return less than the high end -- then we could simplify the test logic.

1 files changed, 32 insertions, 28 deletions

diff --git a/indra/llcommon/tests/llrand_test.cpp b/indra/llcommon/tests/llrand_test.cpp
index 383e6f9e0a..c8e2d19372 100644
--- a/indra/llcommon/tests/llrand_test.cpp
+++ b/indra/llcommon/tests/llrand_test.cpp
@@ -29,7 +29,30 @@
 #include "../test/lltut.h"
 
 #include "../llrand.h"
+#include "stringize.h"
 
+template <typename NUMBER, typename HIGHCOMP>
+void ensure_in_range_using(const std::string_view& name,
+                           NUMBER value, NUMBER low, NUMBER high,
+                           const std::string_view& compdesc, HIGHCOMP&& highcomp)
+{
+    auto failmsg{ stringize(name, " >= ", low, " (", value, ')') };
+    tut::ensure(failmsg, (value >= low));
+    failmsg = stringize(name, ' ', compdesc, ' ', high, " (", value, ')');
+    tut::ensure(failmsg, std::forward<HIGHCOMP>(highcomp)(value, high));
+}
+
+template <typename NUMBER>
+void ensure_in_exc_range(const std::string_view& name, NUMBER value, NUMBER low, NUMBER high)
+{
+    ensure_in_range_using(name, value, low, high, "<", std::less());
+}
+
+template <typename NUMBER>
+void ensure_in_inc_range(const std::string_view& name, NUMBER value, NUMBER low, NUMBER high)
+{
+    ensure_in_range_using(name, value, low, high, "<=", std::less_equal());
+}
 
 namespace tut
 {
@@ -44,84 +67,65 @@ namespace tut
 	template<> template<>
 	void random_object_t::test<1>()
 	{
-		F32 number = 0.0f;
 		for(S32 ii = 0; ii < 100000; ++ii)
 		{
-			number = ll_frand();
-			ensure("frand >= 0", (number >= 0.0f));
-			ensure("frand < 1", (number < 1.0f));
+			ensure_in_exc_range("frand", ll_frand(), 0.0f, 1.0f);
 		}
 	}
 
 	template<> template<>
 	void random_object_t::test<2>()
 	{
-		F64 number = 0.0f;
 		for(S32 ii = 0; ii < 100000; ++ii)
 		{
-			number = ll_drand();
-			ensure("drand >= 0", (number >= 0.0));
-			ensure("drand < 1", (number < 1.0));
+			ensure_in_exc_range("drand", ll_drand(), 0.0, 1.0);
 		}
 	}
 
 	template<> template<>
 	void random_object_t::test<3>()
 	{
-		F32 number = 0.0f;
 		for(S32 ii = 0; ii < 100000; ++ii)
 		{
-			number = ll_frand(2.0f) - 1.0f;
-			ensure("frand >= 0", (number >= -1.0f));
-			ensure("frand < 1", (number <= 1.0f));
+			ensure_in_inc_range("frand(2.0f)", ll_frand(2.0f) - 1.0f, -1.0f, 1.0f);
 		}
 	}
 
 	template<> template<>
 	void random_object_t::test<4>()
 	{
-		F32 number = 0.0f;
 		for(S32 ii = 0; ii < 100000; ++ii)
 		{
-			number = ll_frand(-7.0);
-			ensure("drand <= 0", (number <= 0.0));
-			ensure("drand > -7", (number > -7.0));
+			// Negate the result so we don't have to allow a templated low-end
+			// comparison as well.
+			ensure_in_exc_range("-frand(-7.0)", -ll_frand(-7.0), 0.0f, 7.0f);
 		}
 	}
 
 	template<> template<>
 	void random_object_t::test<5>()
 	{
-		F64 number = 0.0f;
 		for(S32 ii = 0; ii < 100000; ++ii)
 		{
-			number = ll_drand(-2.0);
-			ensure("drand <= 0", (number <= 0.0));
-			ensure("drand > -2", (number > -2.0));
+			ensure_in_exc_range("-drand(-2.0)", -ll_drand(-2.0), 0.0, 2.0);
 		}
 	}
 
 	template<> template<>
 	void random_object_t::test<6>()
 	{
-		S32 number = 0;
 		for(S32 ii = 0; ii < 100000; ++ii)
 		{
-			number = ll_rand(100);
-			ensure("rand >= 0", (number >= 0));
-			ensure("rand < 100", (number < 100));
+			ensure_in_exc_range("rand(100)", ll_rand(100), 0, 100);
 		}
 	}
 
 	template<> template<>
 	void random_object_t::test<7>()
 	{
-		S32 number = 0;
 		for(S32 ii = 0; ii < 100000; ++ii)
 		{
-			number = ll_rand(-127);
-			ensure("rand <= 0", (number <= 0));
-			ensure("rand > -127", (number > -127));
+			ensure_in_exc_range("-rand(-127)", -ll_rand(-127), 0, 127);
 		}
 	}
 }