docs: add missing tests for getting started examples

Add test_metrics.py and test_otlpcollector.py to validate the
metrics_example.py and otlpcollector_example.py scripts.

- test_metrics.py: Validates all 7 metric types with specific expected values
- test_otlpcollector.py: Tests OTLP collector example with graceful timeout handling

Fixes #4001

Author: sginji

docs/getting_started/tests/test_metrics.py

@@ -0,0 +1,81 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+import json
+import os
+import subprocess
+import sys
+import unittest
+
+class TestMetrics(unittest.TestCase):
+    def test_metrics(self):
+        """Test that metrics example produces expected values"""
+        # Run the metrics example
+        dirpath = os.path.dirname(os.path.realpath(__file__))
+        test_script = f"{dirpath}/../metrics_example.py"
+        
+        result = subprocess.run(
+            [sys.executable, test_script],
+            capture_output=True,
+            text=True,
+            timeout=10
+        )
+        
+        # Script should run successfully
+        self.assertEqual(result.returncode, 0)
+        
+        # Parse the JSON output
+        output_data = json.loads(result.stdout)
+        
+        # Get the metrics from the JSON structure
+        metrics = output_data["resource_metrics"][0]["scope_metrics"][0]["metrics"]
+        
+        # Create a lookup dict for easier testing
+        metrics_by_name = {metric["name"]: metric for metric in metrics}
+        
+        # Test Counter: should be 1 (called counter.add(1))
+        counter_metric = metrics_by_name["counter"]
+        counter_value = counter_metric["data"]["data_points"][0]["value"]
+        self.assertEqual(counter_value, 1, "Counter should have value 1")
+        
+        # Test UpDownCounter: should be -4 (1 + (-5) = -4)
+        updown_metric = metrics_by_name["updown_counter"]
+        updown_value = updown_metric["data"]["data_points"][0]["value"]
+        self.assertEqual(updown_value, -4, "UpDownCounter should have value -4")
+        
+        # Test Histogram: should have count=1, sum=99.9
+        histogram_metric = metrics_by_name["histogram"]
+        histogram_data = histogram_metric["data"]["data_points"][0]
+        self.assertEqual(histogram_data["count"], 1, "Histogram should have count 1")
+        self.assertEqual(histogram_data["sum"], 99.9, "Histogram should have sum 99.9")
+        
+        # Test Gauge: should be 1 (last value set)
+        gauge_metric = metrics_by_name["gauge"]
+        gauge_value = gauge_metric["data"]["data_points"][0]["value"]
+        self.assertEqual(gauge_value, 1, "Gauge should have value 1")
+        
+        # Test Observable Counter: should be 1 (from callback)
+        obs_counter_metric = metrics_by_name["observable_counter"]
+        obs_counter_value = obs_counter_metric["data"]["data_points"][0]["value"]
+        self.assertEqual(obs_counter_value, 1, "Observable counter should have value 1")
+        
+        # Test Observable UpDownCounter: should be -10 (from callback)
+        obs_updown_metric = metrics_by_name["observable_updown_counter"]
+        obs_updown_value = obs_updown_metric["data"]["data_points"][0]["value"]
+        self.assertEqual(obs_updown_value, -10, "Observable updown counter should have value -10")
+        
+        # Test Observable Gauge: should be 9 (from callback)
+        obs_gauge_metric = metrics_by_name["observable_gauge"]
+        obs_gauge_value = obs_gauge_metric["data"]["data_points"][0]["value"]
+        self.assertEqual(obs_gauge_value, 9, "Observable gauge should have value 9")

docs/getting_started/tests/test_otlpcollector.py

@@ -0,0 +1,43 @@
+# Copyright The OpenTelemetry Authors
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+# oltpcollector_example.py
+import os
+import subprocess
+import sys
+import unittest
+
+class TestOTLPCollector(unittest.TestCase):
+    def test_otlpcollector(self):
+        """Test that OTLP collector example outputs 'Hello world!'"""
+        dirpath = os.path.dirname(os.path.realpath(__file__))
+        test_script = f"{dirpath}/../otlpcollector_example.py"
+        
+        # Run the script with a short timeout since it will retry forever
+        process = subprocess.Popen(
+            [sys.executable, test_script],
+            stdout=subprocess.PIPE,
+            stderr=subprocess.PIPE,
+            text=True
+        )
+        
+        # Wait 2 seconds then kill it (enough time to print "Hello world!")
+        try:
+            stdout, stderr = process.communicate(timeout=2)
+        except subprocess.TimeoutExpired:
+            process.kill()
+            stdout, stderr = process.communicate()
+        
+        # Check that it printed the expected message
+        self.assertIn("Hello world!", stdout)