LinePerPolicyFileProviderTest.java

/*
 * Copyright The OpenTelemetry Authors
 * SPDX-License-Identifier: Apache-2.0
 */

package io.opentelemetry.contrib.dynamic.policy;

import static org.assertj.core.api.Assertions.assertThat;

import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.util.Arrays;
import java.util.Collections;
import java.util.List;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.io.TempDir;

class LinePerPolicyFileProviderTest {

  private static final String TRACE_SAMPLING_TYPE = "trace-sampling";
  private static final String TRACE_SAMPLING_ALIAS = "trace-sampling.probability";

  @TempDir Path tempDir;

  @Test
  void fetchPoliciesReturnsEmptyWhenFileMissing() throws Exception {
    Path missingFile = tempDir.resolve("missing-policies.txt");
    LinePerPolicyFileProvider provider =
        new LinePerPolicyFileProvider(missingFile, Collections.singletonList(acceptingValidator()));

    List<TelemetryPolicy> policies = provider.fetchPolicies();

    assertThat(policies).isEmpty();
  }

  @Test
  void fetchPoliciesParsesJsonLines() throws Exception {
    Path file = writeLines("{\"trace-sampling\": {\"probability\": 0.5}}");
    LinePerPolicyFileProvider provider =
        new LinePerPolicyFileProvider(file, Collections.singletonList(acceptingValidator()));

    List<TelemetryPolicy> policies = provider.fetchPolicies();

    assertThat(policies).hasSize(1);
    assertThat(policies.get(0).getType()).isEqualTo(TRACE_SAMPLING_TYPE);
  }

  @Test
  void fetchPoliciesParsesAliasLines() throws Exception {
    Path file = writeLines("trace-sampling.probability=0.5");
    LinePerPolicyFileProvider provider =
        new LinePerPolicyFileProvider(file, Collections.singletonList(acceptingValidator()));

    List<TelemetryPolicy> policies = provider.fetchPolicies();

    assertThat(policies).hasSize(1);
    assertThat(policies.get(0).getType()).isEqualTo(TRACE_SAMPLING_TYPE);
  }

  @Test
  void fetchPoliciesSkipsBlankLinesAndComments() throws Exception {
    Path file = writeLines("", "   ", "# comment line", "trace-sampling.probability=0.25");
    LinePerPolicyFileProvider provider =
        new LinePerPolicyFileProvider(file, Collections.singletonList(acceptingValidator()));

    List<TelemetryPolicy> policies = provider.fetchPolicies();

    assertThat(policies).hasSize(1);
    assertThat(policies.get(0).getType()).isEqualTo(TRACE_SAMPLING_TYPE);
  }

  @Test
  void fetchPoliciesSkipsUnknownOrRejectedPolicies() throws Exception {
    PolicyValidator rejectingValidator =
        new TestPolicyValidator(/* acceptJson= */ false, /* acceptAlias= */ false);
    Path file =
        writeLines(
            "{\"trace-sampling\": {\"probability\": 0.5}}",
            "{\"other-policy\": {\"probability\": 0.5}}",
            "other.key=1");
    LinePerPolicyFileProvider provider =
        new LinePerPolicyFileProvider(file, Collections.singletonList(rejectingValidator));

    List<TelemetryPolicy> policies = provider.fetchPolicies();

    assertThat(policies).isEmpty();
  }

  private Path writeLines(String... lines) throws IOException {
    Path file = tempDir.resolve("policies.txt");
    Files.write(file, Arrays.asList(lines));
    return file;
  }

  private static PolicyValidator acceptingValidator() {
    return new TestPolicyValidator(/* acceptJson= */ true, /* acceptAlias= */ true);
  }

  private static class TestPolicyValidator implements PolicyValidator {
    private final boolean acceptJson;
    private final boolean acceptAlias;

    private TestPolicyValidator(boolean acceptJson, boolean acceptAlias) {
      this.acceptJson = acceptJson;
      this.acceptAlias = acceptAlias;
    }

    @Override
    public TelemetryPolicy validate(String json) {
      if (!acceptJson) {
        return null;
      }
      return new TelemetryPolicy(TRACE_SAMPLING_TYPE, null);
    }

    @Override
    public String getPolicyType() {
      return TRACE_SAMPLING_TYPE;
    }

    @Override
    public TelemetryPolicy validateAlias(String key, String value) {
      if (!acceptAlias) {
        return null;
      }
      return new TelemetryPolicy(TRACE_SAMPLING_TYPE, null);
    }

    @Override
    public String getAlias() {
      return TRACE_SAMPLING_ALIAS;
    }
  }
}