Add better support to obfuscate statistics.

1 files changed, 53 insertions, 0 deletions

diff --git a/src/test/test_util.c b/src/test/test_util.c
index b952bb2596..6e73ccf51e 100644
--- a/src/test/test_util.c
+++ b/src/test/test_util.c
@@ -4619,6 +4619,58 @@ test_util_round_to_next_multiple_of(void *arg)
   tt_assert(round_uint64_to_next_multiple_of(99,7) == 105);
   tt_assert(round_uint64_to_next_multiple_of(99,9) == 99);
 
+  tt_assert(round_int64_to_next_multiple_of(0,1) == 0);
+  tt_assert(round_int64_to_next_multiple_of(0,7) == 0);
+
+  tt_assert(round_int64_to_next_multiple_of(99,1) == 99);
+  tt_assert(round_int64_to_next_multiple_of(99,7) == 105);
+  tt_assert(round_int64_to_next_multiple_of(99,9) == 99);
+
+  tt_assert(round_int64_to_next_multiple_of(-99,1) == -99);
+  tt_assert(round_int64_to_next_multiple_of(-99,7) == -98);
+  tt_assert(round_int64_to_next_multiple_of(-99,9) == -99);
+
+  tt_assert(round_int64_to_next_multiple_of(INT64_MIN,2) == INT64_MIN);
+  tt_assert(round_int64_to_next_multiple_of(INT64_MAX,2) ==
+                                            INT64_MAX-INT64_MAX%2);
+ done:
+  ;
+}
+
+static void
+test_util_laplace(void *arg)
+{
+  /* Sample values produced using Python's SciPy:
+   *
+   * >>> from scipy.stats import laplace
+   * >>> laplace.ppf([-0.01, 0.0, 0.01, 0.5, 0.51, 0.99, 1.0, 1.01],
+     ...             loc = 24, scale = 24)
+   * array([          nan,          -inf,  -69.88855213,   24.        ,
+   *          24.48486498,  117.88855213,           inf,           nan])
+   */
+  const double mu = 24.0, b = 24.0;
+  const double delta_f = 15.0, epsilon = 0.3; /* b = 15.0 / 0.3 = 50.0 */
+  (void)arg;
+
+  tt_assert(isinf(sample_laplace_distribution(mu, b, 0.0)));
+  test_feq(-69.88855213, sample_laplace_distribution(mu, b, 0.01));
+  test_feq(24.0, sample_laplace_distribution(mu, b, 0.5));
+  test_feq(24.48486498, sample_laplace_distribution(mu, b, 0.51));
+  test_feq(117.88855213, sample_laplace_distribution(mu, b, 0.99));
+
+  /* >>> laplace.ppf([0.0, 0.1, 0.25, 0.5, 0.75, 0.9, 0.99],
+   * ...             loc = 0, scale = 50)
+   * array([         -inf,  -80.47189562,  -34.65735903,    0.        ,
+   *          34.65735903,   80.47189562,  195.60115027])
+   */
+  tt_assert(LONG_MIN + 20 ==
+            add_laplace_noise(20, 0.0, delta_f, epsilon));
+  tt_assert(-60 == add_laplace_noise(20, 0.1, delta_f, epsilon));
+  tt_assert(-14 == add_laplace_noise(20, 0.25, delta_f, epsilon));
+  tt_assert(20 == add_laplace_noise(20, 0.5, delta_f, epsilon));
+  tt_assert(54 == add_laplace_noise(20, 0.75, delta_f, epsilon));
+  tt_assert(100 == add_laplace_noise(20, 0.9, delta_f, epsilon));
+  tt_assert(215 == add_laplace_noise(20, 0.99, delta_f, epsilon));
  done:
   ;
 }
@@ -4880,6 +4932,7 @@ struct testcase_t util_tests[] = {
   UTIL_LEGACY(strtok),
   UTIL_LEGACY(di_ops),
   UTIL_TEST(round_to_next_multiple_of, 0),
+  UTIL_TEST(laplace, 0),
   UTIL_TEST(strclear, 0),
   UTIL_TEST(find_str_at_start_of_line, 0),
   UTIL_TEST(string_is_C_identifier, 0),