Test cases which may occasionally fail say so in the error message.

platforms/cuda/tests/TestCudaBrownianIntegrator.cpp

@@ -121,7 +121,7 @@ void testTemperature() {
     }
     pe /= steps;
     double expected = 0.5*numBonds*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, pe, 0.1*expected);
+    ASSERT_USUALLY_EQUAL_TOL(expected, pe, 0.1*expected);
 }
 
 void testConstraints() {

platforms/cuda/tests/TestCudaLangevinIntegrator.cpp

@@ -126,7 +126,7 @@ void testTemperature() {
     }
     ke /= 10000;
     double expected = 0.5*numParticles*3*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, ke, 6/std::sqrt(10000.0));
+    ASSERT_USUALLY_EQUAL_TOL(expected, ke, 6/std::sqrt(10000.0));
 }
 
 void testConstraints() {

platforms/cuda/tests/TestCudaVariableLangevinIntegrator.cpp

@@ -126,7 +126,7 @@ void testTemperature() {
     }
     ke /= 1000;
     double expected = 0.5*numParticles*3*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, ke, 3*expected/std::sqrt(1000.0));
+    ASSERT_USUALLY_EQUAL_TOL(expected, ke, 3*expected/std::sqrt(1000.0));
 }
 
 void testConstraints() {

platforms/opencl/tests/TestOpenCLBrownianIntegrator.cpp

@@ -121,7 +121,7 @@ void testTemperature() {
     }
     pe /= steps;
     double expected = 0.5*numBonds*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, pe, 0.1*expected);
+    ASSERT_USUALLY_EQUAL_TOL(expected, pe, 0.1*expected);
 }
 
 void testConstraints() {

platforms/opencl/tests/TestOpenCLLangevinIntegrator.cpp

@@ -126,7 +126,7 @@ void testTemperature() {
     }
     ke /= 10000;
     double expected = 0.5*numParticles*3*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, ke, 6/std::sqrt(10000.0));
+    ASSERT_USUALLY_EQUAL_TOL(expected, ke, 6/std::sqrt(10000.0));
 }
 
 void testConstraints() {

platforms/opencl/tests/TestOpenCLVariableLangevinIntegrator.cpp

@@ -126,7 +126,7 @@ void testTemperature() {
     }
     ke /= 1000;
     double expected = 0.5*numParticles*3*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, ke, 3*expected/std::sqrt(1000.0));
+    ASSERT_USUALLY_EQUAL_TOL(expected, ke, 3*expected/std::sqrt(1000.0));
 }
 
 void testConstraints() {

platforms/reference/tests/TestReferenceBrownianIntegrator.cpp

@@ -119,7 +119,7 @@ void testTemperature() {
     }
     pe /= steps;
     double expected = 0.5*numBonds*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, pe, 0.1*expected);
+    ASSERT_USUALLY_EQUAL_TOL(expected, pe, 0.1*expected);
 }
 
 void testConstraints() {

platforms/reference/tests/TestReferenceLangevinIntegrator.cpp

@@ -126,7 +126,7 @@ void testTemperature() {
     }
     ke /= 10000;
     double expected = 0.5*numParticles*3*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, ke, 6/std::sqrt(10000.0));
+    ASSERT_USUALLY_EQUAL_TOL(expected, ke, 6/std::sqrt(10000.0));
 }
 
 void testConstraints() {

platforms/reference/tests/TestReferenceVariableLangevinIntegrator.cpp

@@ -126,7 +126,7 @@ void testTemperature() {
     }
     ke /= 1000;
     double expected = 0.5*numParticles*3*BOLTZ*temp;
-    ASSERT_EQUAL_TOL(expected, ke, 3*expected/std::sqrt(1000.0));
+    ASSERT_USUALLY_EQUAL_TOL(expected, ke, 3*expected/std::sqrt(1000.0));
 }
 
 void testConstraints() {

tests/AssertionUtilities.h

@@ -62,4 +62,6 @@ void throwException(const char* file, int line, const std::string& details) {
 
 #define ASSERT_EQUAL_VEC(expected, found, tol) {ASSERT_EQUAL_TOL((expected)[0], (found)[0], (tol)); ASSERT_EQUAL_TOL((expected)[1], (found)[1], (tol)); ASSERT_EQUAL_TOL((expected)[2], (found)[2], (tol));};
 
+#define ASSERT_USUALLY_EQUAL_TOL(expected, found, tol) {double _scale_ = std::fabs(expected) > 1.0 ? std::fabs(expected) : 1.0; if (!(std::fabs((expected)-(found))/_scale_ <= (tol))) {std::stringstream details; details << "Expected "<<(expected)<<", found "<<(found)<<" (This test is stochastic and may occasionally fail)"; throwException(__FILE__, __LINE__, details.str());}};
+
 #endif /*OPENMM_ASSERTIONUTILITIES_H_*/