Write API unit tests

[AKorpusenko]

:red_circle: Description

Write a script which allows to test all APIs of Golos node.

:red_circle: In progress

Here you can see the progress. Following API methods have to covered with the tests:

• [x] witness_api::get_current_median_history_price
• [x] witness_api::get_feed_history
• [x] witness_api::get_miner_queue
• [x] witness_api::get_witness_schedule
• [x] witness_api::get_witnesses
• [x] witness_api::get_witness_by_account
• [x] witness_api::get_witnesses_by_vote
• [x] witness_api::get_witness_count
• [x] witness_api::lookup_witness_accounts
• [x] witness_api::get_active_witnesses
• [x] account_history::get_account_history
• [x] operation_history::get_ops_in_block
• [x] operation_history::get_transaction
• [x] tags::get_trending_tags
• [x] tags::get_tags_used_by_author
• [ ] tags::get_discussions_by_payout
• [ ] tags::get_discussions_by_trending
• [x] tags::get_discussions_by_created
• [x] tags::get_discussions_by_active
• [x] tags::get_discussions_by_cashout
• [x] tags::get_discussions_by_votes
• [x] tags::get_discussions_by_children
• [x] tags::get_discussions_by_hot
• [x] tags::get_discussions_by_feed
• [x] tags::get_discussions_by_blog
• [x] tags::get_discussions_by_comments
• [x] tags::get_discussions_by_promoted
• [x] tags::get_discussions_by_author_before_date
• [x] tags::get_languages
• [x] social_network::get_replies_by_last_update
• [x] social_network::get_content
• [x] social_network::get_content_replies
• [x] social_network::get_all_content_replies
• [x] social_network::get_active_votes
• [x] social_network::get_account_votes
• [x] database_api::get_block_header
• [x] database_api::get_block
• [x] database_api::get_config
• [x] database_api::get_dynamic_global_properties
• [x] database_api::get_chain_properties
• [x] database_api::get_hardfork_version
• [x] database_api::get_next_scheduled_hardfork
• [x] database_api::get_account_count
• [x] database_api::get_owner_history
• [x] database_api::get_recovery_request
• [x] database_api::get_escrow
• [x] database_api::get_withdraw_routes
• [x] database_api::get_account_bandwidth
• [ ] database_api::get_savings_withdraw_from
• [ ] database_api::get_savings_withdraw_to
• [ ] database_api::get_conversion_requests
• [ ] database_api::get_transaction_hex
• [ ] database_api::get_required_signatures
• [ ] database_api::get_potential_signatures
• [ ] database_api::verify_authority
• [ ] database_api::verify_account_authority
• [ ] database_api::get_accounts
• [ ] database_api::lookup_account_names
• [ ] database_api::lookup_accounts
• [x] database_api::get_proposed_transaction
• [x] database_api::get_database_info
• [ ] database_api::get_vesting_delegations
• [ ] database_api::get_expiring_vesting_delegations
• [x] follow::get_followers
• [x] follow::get_following
• [x] follow::get_follow_count
• [x] follow::get_feed_entries
• [x] follow::get_feed
• [x] follow::get_blog_entries
• [x] follow::get_blog
• [x] follow::get_account_reputations
• [x] follow::get_reblogged_by
• [x] follow::get_blog_authors
• [x] account_by_key::get_key_references
• [ ] network_broadcast_api::broadcast_transaction
• [ ] network_broadcast_api::broadcast_transaction_with_callback
• [ ] network_broadcast_api::broadcast_transaction_synchronous
• [ ] network_broadcast_api::broadcast_block
• [x] market_history::get_ticker
• [x] market_history::get_volume
• [x] market_history::get_order_book
• [x] market_history::get_order_book_extended
• [x] market_history::get_trade_history
• [x] market_history::get_recent_trades
• [x] market_history::get_market_history
• [x] market_history::get_market_history_buckets
• [x] market_history::get_open_orders