test: add tests redis disabling

Signed-off-by: Arjun Rajappa <Arjun.Rajappa@ibm.com>

Author: arjun-rajappa

test/instrumentation/redis_disable_test.rb

@@ -0,0 +1,155 @@
+# (c) Copyright IBM Corp. 2025
+
+require 'test_helper'
+
+class RedisDisableTest < Minitest::Test
+  def setup
+    @redis_url = if ENV.key?('REDIS_URL')
+                   ENV['REDIS_URL']
+                 else
+                   "redis://localhost:6379"
+                 end
+    @redis_client = Redis.new(url: @redis_url)
+
+    # Reset span filtering configuration before each test
+    ::Instana::SpanFiltering.reset
+    ::Instana::SpanFiltering.initialize
+
+    # Reset Redis configuration
+    ::Instana.config[:redis] = { :enabled => true }
+
+    clear_all!
+  end
+
+  def teardown
+    # Reset span filtering configuration after each test
+    ::Instana::SpanFiltering.reset
+    ::Instana::SpanFiltering.initialize
+
+    # Reset Redis configuration
+    ::Instana.config[:redis] = { :enabled => true }
+  end
+
+  def test_redis_disabled_by_configuration
+    # Set Redis to be disabled via configuration
+    ::Instana.config[:redis][:enabled] = false
+
+    # Execute Redis operation
+    Instana.tracer.in_span(:redis_test) do
+      @redis_client.set('hello', 'world')
+    end
+
+    # Verify that only the parent span is reported (Redis span is disabled)
+    spans = ::Instana.processor.queued_spans
+    assert_equal 1, spans.length
+    assert_equal :sdk, spans[0][:n]
+  end
+
+  def test_redis_disabled_via_databases_category
+    # Create a mock configuration that disables the databases category
+    config = ::Instana::SpanFiltering::Configuration.new
+
+    # Simulate disabling databases category
+    config.send(:update_instana_config_for_disabled_technology, 'databases')
+
+    # Execute Redis operation
+    Instana.tracer.in_span(:redis_test) do
+      @redis_client.set('hello', 'world')
+    end
+
+    # Verify that only the parent span is reported (Redis span is disabled)
+    spans = ::Instana.processor.queued_spans
+    assert_equal 1, spans.length
+    assert_equal :sdk, spans[0][:n]
+  end
+
+  def test_redis_disabled_via_yaml_config
+    # Create a test YAML configuration file
+    yaml_content = <<~YAML
+      tracing:
+        disable:
+          - redis
+    YAML
+
+    File.write('test_redis_config.yaml', yaml_content)
+    ENV['INSTANA_CONFIG_PATH'] = 'test_redis_config.yaml'
+
+    # Create a new configuration that should load from our YAML file
+    ::Instana::SpanFiltering::Configuration.new
+
+    # Execute Redis operation
+    Instana.tracer.in_span(:redis_test) do
+      @redis_client.set('hello', 'world')
+    end
+
+    # Verify that only the parent span is reported (Redis span is disabled)
+    spans = ::Instana.processor.queued_spans
+    assert_equal 1, spans.length
+    assert_equal :sdk, spans[0][:n]
+  ensure
+    # Remove test config file
+    File.unlink('test_redis_config.yaml') if File.exist?('test_redis_config.yaml')
+    ENV.delete('INSTANA_CONFIG_PATH')
+  end
+
+  def test_redis_disabled_via_env_var
+    # Set environment variable to disable Redis
+    ENV['INSTANA_TRACING_DISABLE'] = 'redis'
+
+    # Create a new configuration that should load from our environment variable
+    ::Instana::SpanFiltering::Configuration.new
+
+    # Execute Redis operation
+    Instana.tracer.in_span(:redis_test) do
+      @redis_client.set('hello', 'world')
+    end
+
+    # Verify that only the parent span is reported (Redis span is disabled)
+    spans = ::Instana.processor.queued_spans
+    assert_equal 1, spans.length
+    assert_equal :sdk, spans[0][:n]
+  ensure
+    ENV.delete('INSTANA_TRACING_DISABLE')
+  end
+
+  def test_redis_disabled_via_databases_env_var
+    # Set environment variable to disable databases category
+    ENV['INSTANA_TRACING_DISABLE'] = 'databases'
+
+    # Create a new configuration that should load from our environment variable
+    ::Instana::SpanFiltering::Configuration.new
+
+    # Execute Redis operation
+    Instana.tracer.in_span(:redis_test) do
+      @redis_client.set('hello', 'world')
+    end
+
+    # Verify that only the parent span is reported (Redis span is disabled)
+    spans = ::Instana.processor.queued_spans
+    assert_equal 1, spans.length
+    assert_equal :sdk, spans[0][:n]
+  ensure
+    ENV.delete('INSTANA_TRACING_DISABLE')
+  end
+
+  def test_redis_not_disabled_by_default
+    # Execute Redis operation
+    Instana.tracer.in_span(:redis_test) do
+      @redis_client.set('hello', 'world')
+    end
+
+    # Verify that both spans are reported (Redis span is not disabled)
+    spans = ::Instana.processor.queued_spans
+    assert_equal 2, spans.length
+    first_span, second_span = spans.to_a.reverse
+    assert_equal :sdk, first_span[:n]
+    assert_equal :redis, second_span[:n]
+  end
+
+  private
+
+  def clear_all!
+    ::Instana.processor.clear!
+    ::Instana.tracer.clear!
+  end
+end

test/instrumentation/redis_test.rb

@@ -5,6 +5,7 @@
 
 class RedisTest < Minitest::Test
   def setup
+    ::Instana.config[:redis] = { :enabled => true }
     if ENV.key?('REDIS_URL')
       @redis_url = ENV['REDIS_URL']
     else