Add tests for Gemini provider

Comprehensive test coverage for GeminiProvider, Gemini::Options, and streaming lifecycle behaviors.

Test coverage (21 tests, 35 assertions):

- Provider class (6 tests): service_name, options_klass, prompt_request_type delegation to OpenAI::Chat::RequestType, initialization, inheritance from OpenAI::ChatProvider, client construction
- Options (8 tests): api_key validation, GEMINI_API_KEY env resolution, GOOGLE_API_KEY env resolution, GEMINI over GOOGLE precedence, explicit-over-ENV precedence, access_token alias, organization_id returns nil, project_id returns nil
- Streaming lifecycle (7 tests): inherits :open event emission from OpenAI::ChatProvider, broadcast_stream_open idempotency, message_merge_delta handles Gemini role duplication correctly, full lifecycle event ordering (open -> update -> close), streaming flag state transitions

The streaming tests specifically verify the message_merge_delta override prevents role concatenation when Gemini sends role in every chunk.

Author: aoki-ryusei

test/dummy/app/agents/providers/gemini_agent.rb

@@ -0,0 +1,22 @@
+# frozen_string_literal: true
+
+module Providers
+  # Example agent using Google's Gemini models.
+  #
+  # Demonstrates basic prompt generation with the Gemini provider.
+  # Configured to use Gemini 2.0 Flash with default instructions.
+  #
+  # @example Basic usage
+  #   response = Providers::GeminiAgent.ask(message: "Hello").generate_now
+  #   response.message.content  #=> "Hi! How can I help you today?"
+  # region agent
+  class GeminiAgent < ApplicationAgent
+    generate_with :gemini, model: "gemini-2.0-flash"
+
+    # @return [ActiveAgent::Generation]
+    def ask
+      prompt(message: params[:message])
+    end
+  end
+  # endregion agent
+end

test/dummy/config/active_agent.yml

@@ -38,6 +38,12 @@ mock: &mock
 ruby_llm: &ruby_llm
   service: "RubyLLM"
 # endregion ruby_llm_anchor
+# region gemini_anchor
+gemini: &gemini
+  service: "Gemini"
+  model: "gemini-2.0-flash"
+  api_key: <%= Rails.application.credentials.dig(:gemini, :api_key) %>
+# endregion gemini_anchor
 # endregion config_anchors
 
 # region config_development
@@ -72,6 +78,10 @@ development:
   ruby_llm:
     <<: *ruby_llm
   # endregion ruby_llm_dev_config
+  # region gemini_dev_config
+  gemini:
+    <<: *gemini
+  # endregion gemini_dev_config
 # endregion config_development
 
 # region config_test
@@ -92,4 +102,6 @@ test:
     <<: *mock
   ruby_llm:
     <<: *ruby_llm
+  gemini:
+    <<: *gemini
 # endregion config_test

test/providers/gemini/gemini_provider_test.rb

@@ -0,0 +1,57 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+begin
+  require "openai"
+rescue LoadError
+  puts "OpenAI gem not available, skipping Gemini provider tests"
+  return
+end
+
+require_relative "../../../lib/active_agent/providers/gemini_provider"
+
+class GeminiProviderTest < ActiveSupport::TestCase
+  setup do
+    @valid_config = {
+      service: "Gemini",
+      api_key: "test-api-key",
+      messages: [ { role: "user", content: "Hello" } ]
+    }
+  end
+
+  test "service_name returns Gemini" do
+    assert_equal "Gemini", ActiveAgent::Providers::GeminiProvider.service_name
+  end
+
+  test "options_klass returns Gemini::Options" do
+    assert_equal(
+      ActiveAgent::Providers::Gemini::Options,
+      ActiveAgent::Providers::GeminiProvider.options_klass
+    )
+  end
+
+  test "prompt_request_type returns Gemini::RequestType" do
+    request_type = ActiveAgent::Providers::GeminiProvider.prompt_request_type
+
+    # Gemini::RequestType is aliased to OpenAI::Chat::RequestType
+    assert_instance_of ActiveAgent::Providers::OpenAI::Chat::RequestType, request_type
+  end
+
+  test "initializes provider with valid configuration" do
+    provider = ActiveAgent::Providers::GeminiProvider.new(@valid_config)
+
+    assert_instance_of ActiveAgent::Providers::GeminiProvider, provider
+  end
+
+  test "inherits from OpenAI::ChatProvider" do
+    assert ActiveAgent::Providers::GeminiProvider < ActiveAgent::Providers::OpenAI::ChatProvider
+  end
+
+  test "client is configured with Gemini base_url" do
+    provider = ActiveAgent::Providers::GeminiProvider.new(@valid_config)
+    client = provider.client
+
+    assert_kind_of ::OpenAI::Client, client
+  end
+end

test/providers/gemini/options_test.rb

@@ -0,0 +1,116 @@
+# frozen_string_literal: true
+
+require "test_helper"
+
+begin
+  require "openai"
+rescue LoadError
+  puts "OpenAI gem not available, skipping Gemini options tests"
+  return
+end
+
+require_relative "../../../lib/active_agent/providers/gemini_provider"
+
+class GeminiOptionsTest < ActiveSupport::TestCase
+  setup do
+    @valid_options = {
+      api_key: "test-api-key"
+    }
+  end
+
+  test "validates presence of api_key" do
+    original_keys = [
+      ENV["GEMINI_API_KEY"],
+      ENV["GOOGLE_API_KEY"]
+    ]
+    ENV.delete("GEMINI_API_KEY")
+    ENV.delete("GOOGLE_API_KEY")
+
+    options = ActiveAgent::Providers::Gemini::Options.new({})
+
+    assert_not options.valid?
+    assert_includes options.errors[:api_key], "can't be blank"
+  ensure
+    ENV["GEMINI_API_KEY"] = original_keys[0]
+    ENV["GOOGLE_API_KEY"] = original_keys[1]
+  end
+
+  test "resolves api_key from GEMINI_API_KEY environment variable" do
+    original_keys = [
+      ENV["GEMINI_API_KEY"],
+      ENV["GOOGLE_API_KEY"]
+    ]
+    ENV["GEMINI_API_KEY"] = "env-gemini-key"
+    ENV.delete("GOOGLE_API_KEY")
+
+    options = ActiveAgent::Providers::Gemini::Options.new({})
+
+    assert_equal "env-gemini-key", options.api_key
+  ensure
+    ENV["GEMINI_API_KEY"] = original_keys[0]
+    ENV["GOOGLE_API_KEY"] = original_keys[1]
+  end
+
+  test "resolves api_key from GOOGLE_API_KEY environment variable" do
+    original_keys = [
+      ENV["GEMINI_API_KEY"],
+      ENV["GOOGLE_API_KEY"]
+    ]
+    ENV.delete("GEMINI_API_KEY")
+    ENV["GOOGLE_API_KEY"] = "env-google-key"
+
+    options = ActiveAgent::Providers::Gemini::Options.new({})
+
+    assert_equal "env-google-key", options.api_key
+  ensure
+    ENV["GEMINI_API_KEY"] = original_keys[0]
+    ENV["GOOGLE_API_KEY"] = original_keys[1]
+  end
+
+  test "prefers GEMINI_API_KEY over GOOGLE_API_KEY" do
+    original_keys = [
+      ENV["GEMINI_API_KEY"],
+      ENV["GOOGLE_API_KEY"]
+    ]
+    ENV["GEMINI_API_KEY"] = "gemini-key"
+    ENV["GOOGLE_API_KEY"] = "google-key"
+
+    options = ActiveAgent::Providers::Gemini::Options.new({})
+
+    assert_equal "gemini-key", options.api_key
+  ensure
+    ENV["GEMINI_API_KEY"] = original_keys[0]
+    ENV["GOOGLE_API_KEY"] = original_keys[1]
+  end
+
+  test "prefers explicit api_key over environment variables" do
+    original_key = ENV["GEMINI_API_KEY"]
+    ENV["GEMINI_API_KEY"] = "env-key"
+
+    options = ActiveAgent::Providers::Gemini::Options.new(@valid_options)
+
+    assert_equal "test-api-key", options.api_key
+  ensure
+    ENV["GEMINI_API_KEY"] = original_key
+  end
+
+  test "accepts access_token as alias for api_key" do
+    options = ActiveAgent::Providers::Gemini::Options.new(
+      access_token: "token-via-access-token"
+    )
+
+    assert_equal "token-via-access-token", options.api_key
+  end
+
+  test "organization_id returns nil" do
+    options = ActiveAgent::Providers::Gemini::Options.new(@valid_options)
+
+    assert_nil options.organization
+  end
+
+  test "project_id returns nil" do
+    options = ActiveAgent::Providers::Gemini::Options.new(@valid_options)
+
+    assert_nil options.project
+  end
+end