New sampler tests

CHANGELOG.md

@@ -8,7 +8,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 ## [Unreleased](https://github.com/open-telemetry/opentelemetry-python/compare/v1.13.0...HEAD)
 
 - Enabled custom samplers via entry points
-  ([#XXX](https://github.com/open-telemetry/opentelemetry-python/pull/XXX))
+  ([#2972](https://github.com/open-telemetry/opentelemetry-python/pull/2972))
 - Update explicit histogram bucket boundaries
   ([#2947](https://github.com/open-telemetry/opentelemetry-python/pull/2947))
 

opentelemetry-sdk/src/opentelemetry/sdk/trace/sampling.py

@@ -93,7 +93,7 @@ class CustomSampler(TraceIdRatioBased):
 Sampling probability can be set with ``OTEL_TRACES_SAMPLER_ARG`` if the sampler is a ``TraceIdRatioBased`` Sampler, such as ``traceidratio`` and ``parentbased_traceidratio``. When not provided rate will be set to 1.0 (maximum rate possible).
 
 
-Prev example but with environment vairables. Please make sure to set the env ``OTEL_TRACES_SAMPLER=traceidratio`` and ``OTEL_TRACES_SAMPLER_ARG=0.001``.
+Prev example but with environment variables. Please make sure to set the env ``OTEL_TRACES_SAMPLER=traceidratio`` and ``OTEL_TRACES_SAMPLER_ARG=0.001``.
 
 .. code:: python
 
@@ -404,15 +404,17 @@ def _get_from_env_or_default() -> Sampler:
 
     if trace_sampler_name in _KNOWN_INITIALIZED_SAMPLERS:
         return _KNOWN_INITIALIZED_SAMPLERS[trace_sampler_name]
-    
+
     trace_sampler_impl = None
     if trace_sampler_name in _KNOWN_SAMPLER_CLASSES:
         trace_sampler_impl = _KNOWN_SAMPLER_CLASSES[trace_sampler_name]
     else:
         try:
             trace_sampler_impl = _import_sampler(trace_sampler_name)
         except RuntimeError as err:
-            _logger.warning("Couldn't recognize sampler %s: %s", trace_sampler_name, err)
+            _logger.warning(
+                "Unable to recognize sampler %s: %s", trace_sampler_name, err
+            )
             return _KNOWN_INITIALIZED_SAMPLERS["parentbased_always_on"]
 
     if issubclass(trace_sampler_impl, TraceIdRatioBased):

opentelemetry-sdk/tests/trace/test_trace.py

@@ -139,6 +139,16 @@ def test_tracer_provider_accepts_concurrent_multi_span_processor(self):
         )
 
 
+class CustomSampler(sampling.Sampler):
+    def __init__():
+        super()
+
+
+class CustomRatioSampler(sampling.TraceIdRatioBased):
+    def __init__(ratio):
+        super(ratio)
+
+
 class TestTracerSampling(unittest.TestCase):
     def tearDown(self):
         reload(trace)
@@ -219,7 +229,9 @@ def test_ratio_sampler_with_env(self):
         self.assertIsInstance(tracer_provider.sampler, sampling.ParentBased)
         self.assertEqual(tracer_provider.sampler._root.rate, 0.25)
 
-    @mock.patch.dict("os.environ", {OTEL_TRACES_SAMPLER: "non_existent_entry_point"})
+    @mock.patch.dict(
+        "os.environ", {OTEL_TRACES_SAMPLER: "non_existent_entry_point"}
+    )
     def test_sampler_with_env_non_existent_entry_point(self):
         # pylint: disable=protected-access
         reload(trace)
@@ -228,6 +240,30 @@ def test_sampler_with_env_non_existent_entry_point(self):
         # pylint: disable=protected-access
         self.assertEqual(tracer_provider.sampler._root, sampling.ALWAYS_ON)
 
+    @mock.patch("opentelemetry.sdk.util._import_config_components")
+    @mock.patch.dict("os.environ", {OTEL_TRACES_SAMPLER: "custom_sampler"})
+    def test_custom_sampler_with_env(self, mock_import_config_components):
+        # pylint: disable=protected-access
+        reload(trace)
+        mock_import_config_components.return_value =  [("custom_sampler", CustomSampler)]
+        tracer_provider = trace.TracerProvider()
+        self.assertIsInstance(tracer_provider.sampler, CustomSampler)
+
+    @mock.patch("opentelemetry.sdk.util._import_config_components")
+    @mock.patch.dict(
+        "os.environ",
+        {
+            OTEL_TRACES_SAMPLER: "custom_ratio_sampler",
+            OTEL_TRACES_SAMPLER_ARG: "0.5",
+        },
+    )
+    def test_custom_ratio_sampler_with_env(self, mock_import_config_components):
+        # pylint: disable=protected-access
+        reload(trace)
+        mock_import_config_components.return_value =  [("custom_ratio_sampler", CustomRatioSampler)]
+        tracer_provider = trace.TracerProvider()
+        self.assertIsInstance(tracer_provider.sampler, CustomRatioSampler)
+        self.assertEqual(tracer_provider.sampler._root.rate, 0.5)
 
 class TestSpanCreation(unittest.TestCase):
     def test_start_span_invalid_spancontext(self):