add unit tests for sampling functions

src/sentry_core.h

@@ -88,4 +88,12 @@ void sentry__options_unlock(void);
     for (sentry_options_t *Options = sentry__options_lock(); Options;          \
          sentry__options_unlock(), Options = NULL)
 
+// these for now are only needed for tests
+#ifdef SENTRY_UNITTEST
+bool sentry__is_unsampled(double sample_rate);
+bool sentry__should_skip_transaction(sentry_value_t tx_cxt);
+bool sentry__should_skip_event(
+    const sentry_options_t *options, sentry_value_t event);
+#endif
+
 #endif

tests/unit/CMakeLists.txt

@@ -29,6 +29,7 @@ add_executable(sentry_test_unit
 	test_mpack.c
 	test_path.c
 	test_ratelimiter.c
+	test_sampling.c
 	test_session.c
 	test_slice.c
 	test_symbolizer.c

tests/unit/test_sampling.c

@@ -0,0 +1,67 @@
+#include "sentry_core.h"
+#include "sentry_testsupport.h"
+
+SENTRY_TEST(sampling_decision)
+{
+    TEST_CHECK(sentry__is_unsampled(0.0));
+    TEST_CHECK(sentry__is_unsampled(1.0) == false);
+    TEST_CHECK(sentry__is_unsampled(2.0) == false);
+}
+
+SENTRY_TEST(sampling_transaction)
+{
+    sentry_options_t *options = sentry_options_new();
+    TEST_CHECK(sentry_init(options) == 0);
+
+    // TODO: replace with proper construction of a transaction, e.g.
+    // new_transaction_context -> transaction_context_set_sampled ->
+    // start_transaction
+    // using transaction context in place of a full transaction for now.
+    sentry_value_t tx_cxt = sentry_value_new_transaction_context("honk");
+
+    sentry_transaction_context_set_sampled(tx_cxt, 0);
+    TEST_CHECK(sentry__should_skip_transaction(tx_cxt));
+
+    sentry_transaction_context_set_sampled(tx_cxt, 1);
+    TEST_CHECK(sentry__should_skip_transaction(tx_cxt) == false);
+
+    // fall back to default in sentry options (0.0) if sampled isn't there
+    sentry_transaction_context_remove_sampled(tx_cxt);
+    TEST_CHECK(sentry__should_skip_transaction(tx_cxt));
+
+    options = sentry_options_new();
+    sentry_options_set_traces_sample_rate(options, 1.0);
+    TEST_CHECK(sentry_init(options) == 0);
+
+    TEST_CHECK(sentry__should_skip_transaction(tx_cxt) == false);
+
+    sentry_value_decref(tx_cxt);
+}
+
+SENTRY_TEST(sampling_event)
+{
+    // default is to sample all (error) events, and to not sample any
+    // transactions
+    sentry_options_t *options = sentry_options_new();
+
+    sentry_value_t event = sentry_value_new_object();
+    sentry_value_set_by_key(event, "sampled", sentry_value_new_bool(0));
+
+    // events ignore sampled field if they're not transactions
+    TEST_CHECK(sentry__should_skip_event(options, event) == false);
+
+    // respect sampled field if it is a transaction
+    sentry_value_set_by_key(
+        event, "type", sentry_value_new_string("transaction"));
+    TEST_CHECK(sentry__should_skip_event(options, event));
+
+    // if the sampled field isn't set on a transaction, don't ever send
+    // transactions even if the option says to do so
+    sentry_value_remove_by_key(event, "sampled");
+    TEST_CHECK(sentry__should_skip_event(options, event));
+    sentry_options_set_traces_sample_rate(options, 1.0);
+    TEST_CHECK(sentry__should_skip_event(options, event));
+
+    sentry_value_decref(event);
+    sentry_options_free(options);
+}

tests/unit/tests.inc

@@ -39,6 +39,9 @@ XX(procmaps_parser)
 XX(rate_limit_parsing)
 XX(recursive_paths)
 XX(sampling_before_send)
+XX(sampling_decision)
+XX(sampling_event)
+XX(sampling_transaction)
 XX(serialize_envelope)
 XX(session_basics)
 XX(slice)