Fix get exporter names condition (#1707)

Author: dtaniwaki

CHANGELOG.md

@@ -68,6 +68,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
   ([#1695](https://github.com/open-telemetry/opentelemetry-python/pull/1695))
 - Change Jaeger exporters to obtain service.name from span
   ([#1703](https://github.com/open-telemetry/opentelemetry-python/pull/1703))
+- Fixed an unset `OTEL_TRACES_EXPORTER` resulting in an error
+  ([#1707](https://github.com/open-telemetry/opentelemetry-python/pull/1707))
 
 ### Removed
 - Removed unused `get_hexadecimal_trace_id` and `get_hexadecimal_span_id` methods.

opentelemetry-distro/src/opentelemetry/distro/__init__.py

@@ -50,10 +50,7 @@ def _get_exporter_names() -> Sequence[str]:
 
     exporters = set()
 
-    if (
-        trace_exporters is not None
-        or trace_exporters.lower().strip() != "none"
-    ):
+    if trace_exporters and trace_exporters.lower().strip() != "none":
         exporters.update(
             {
                 trace_exporter.strip()

opentelemetry-distro/tests/test_configurator.py

@@ -167,3 +167,15 @@ def test_otlp_exporter_overwrite(self):
     @patch.dict(environ, {OTEL_TRACES_EXPORTER: "jaeger,zipkin"})
     def test_multiple_exporters(self):
         self.assertEqual(sorted(_get_exporter_names()), ["jaeger", "zipkin"])
+
+    @patch.dict(environ, {OTEL_TRACES_EXPORTER: "none"})
+    def test_none_exporters(self):
+        self.assertEqual(sorted(_get_exporter_names()), [])
+
+    @patch.dict(environ, {}, clear=True)
+    def test_no_exporters(self):
+        self.assertEqual(sorted(_get_exporter_names()), [])
+
+    @patch.dict(environ, {OTEL_TRACES_EXPORTER: ""})
+    def test_empty_exporters(self):
+        self.assertEqual(sorted(_get_exporter_names()), [])