Add snapshot tests for prometheus text format

exporter/opentelemetry-exporter-prometheus/test-requirements.txt

@@ -11,6 +11,7 @@ py==1.11.0
 py-cpuinfo==9.0.0
 pytest==7.1.3
 pytest-benchmark==4.0.0
+syrupy==4.6.1
 tomli==2.0.1
 typing_extensions==4.10.0
 wrapt==1.16.0

exporter/opentelemetry-exporter-prometheus/tests/__snapshots__/test_prometheus_text_format.ambr

@@ -0,0 +1,22 @@
+# serializer version: 1
+# name: test_counter2
+  '''
+  # HELP test_with_collision_total My description
+  # TYPE test_with_collision_total counter
+  test_with_collision_total{hello_world="hello_world"} 1.0
+  '''
+# ---
+# name: test_counter[my.counter.name-s]
+  '''
+  # HELP my_counter_name_seconds_total My description
+  # TYPE my_counter_name_seconds_total counter
+  my_counter_name_seconds_total{foo1_bar_baz="hello world"} 10.0
+  '''
+# ---
+# name: test_counter[request.count-{requests}]
+  '''
+  # HELP request_count_total My description
+  # TYPE request_count_total counter
+  request_count_total{foo1_bar_baz="hello world"} 10.0
+  '''
+# ---

exporter/opentelemetry-exporter-prometheus/tests/test_prometheus_text_format.py

@@ -0,0 +1,79 @@
+# 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.
+
+from typing import Callable, Iterable
+from syrupy import SnapshotAssertion
+
+import pytest
+from prometheus_client import generate_latest
+
+from opentelemetry.exporter.prometheus import PrometheusMetricReader
+from opentelemetry.sdk.metrics import MeterProvider
+
+
+@pytest.fixture
+def prometheus_metric_reader() -> PrometheusMetricReader:
+    return PrometheusMetricReader(disable_target_info=True)
+
+
+@pytest.fixture
+def meter_provider(
+    prometheus_metric_reader: PrometheusMetricReader,
+) -> Iterable[MeterProvider]:
+    mp = MeterProvider(metric_readers=[prometheus_metric_reader])
+    yield mp
+    mp.shutdown(timeout_millis=100)
+
+
+@pytest.fixture
+def get_prometheus_text(
+    prometheus_metric_reader: PrometheusMetricReader,
+) -> Callable[[], str]:
+    def result() -> str:
+        result_bytes = generate_latest(prometheus_metric_reader._collector)
+        return result_bytes.decode("utf-8").strip()
+
+    return result
+
+
+@pytest.mark.parametrize(
+    "counter_name,unit",
+    [("my.counter.name", "s"), ("request.count", "{requests}")],
+)
+def test_counter(
+    counter_name: str,
+    unit: str,
+    meter_provider: MeterProvider,
+    get_prometheus_text: Callable[[], str],
+    snapshot: SnapshotAssertion,
+) -> None:
+    counter = meter_provider.get_meter("scope").create_counter(
+        counter_name, unit=unit, description="My description"
+    )
+    counter.add(10, {"foo1.bar:baz": "hello world"})
+    assert get_prometheus_text() == snapshot
+
+
+def test_counter2(
+    meter_provider: MeterProvider,
+    get_prometheus_text: Callable[[], str],
+    snapshot: SnapshotAssertion,
+) -> None:
+    counter = meter_provider.get_meter("scope").create_counter(
+        "test.with.collision", unit="1", description="My description"
+    )
+    counter.add(
+        1, {"hello_world": "hello_world", "hello.world": "hello.world"}
+    )
+    assert get_prometheus_text() == snapshot