test: cover CacheStoreTest, test_write_then_read_round_trips

test/test_cache_store.rb

@@ -0,0 +1,116 @@
+require 'minitest/autorun'
+require 'prism'
+
+class CacheStoreTest < Minitest::Test
+  def setup
+    @store = Prism::Cache::MemoryStore.new
+  end
+
+  def test_write_then_read_round_trips
+    @store.write('key', 'value')
+    assert_equal 'value', @store.read('key')
+  end
+
+  def test_read_of_missing_key_is_nil
+    assert_nil @store.read('missing')
+  end
+
+  def test_keys_are_coerced_to_string
+    @store.write(:sym_key, 'value')
+    assert_equal 'value', @store.read('sym_key')
+  end
+
+  def test_fetch_computes_and_stores_on_miss
+    calls = 0
+    3.times { @store.fetch('k') { calls += 1; 'computed' } }
+    assert_equal 1, calls
+  end
+
+  def test_fetch_returns_existing_value_without_yielding_on_hit
+    @store.write('k', 'preset')
+    result = @store.fetch('k') { raise 'must not be called' }
+    assert_equal 'preset', result
+  end
+
+  def test_delete_removes_the_entry
+    @store.write('k', 'v')
+    assert @store.delete('k')
+    assert_nil @store.read('k')
+  end
+
+  def test_delete_of_missing_key_returns_falsey
+    refute @store.delete('missing')
+  end
+
+  def test_exist_reflects_presence
+    refute @store.exist?('k')
+    @store.write('k', 'v')
+    assert @store.exist?('k')
+  end
+
+  def test_clear_empties_the_store
+    @store.write('a', 1)
+    @store.write('b', 2)
+    @store.clear
+    assert_equal 0, @store.size
+  end
+
+  def test_expires_in_makes_the_entry_unreadable_afterwards
+    @store.write('k', 'v', expires_in: 0)
+    sleep 0.01
+    assert_nil @store.read('k')
+  end
+
+  def test_delete_matched_removes_keys_matching_a_regexp
+    @store.write('posts/1', 'a')
+    @store.write('posts/2', 'b')
+    @store.write('users/1', 'c')
+    @store.delete_matched(/\Aposts\//)
+    assert_nil @store.read('posts/1')
+    assert_nil @store.read('posts/2')
+    assert_equal 'c', @store.read('users/1')
+  end
+
+  def test_default_store_is_a_memory_store_singleton
+    assert_same Prism::Cache.store, Prism::Cache.store
+    assert_instance_of Prism::Cache::MemoryStore, Prism::Cache.store
+  end
+
+  def test_unbounded_store_never_evicts
+    store = Prism::Cache::MemoryStore.new
+    50.times { |i| store.write("k#{i}", i) }
+    assert_equal 50, store.size
+  end
+
+  def test_max_size_evicts_the_least_recently_used_entry_on_write
+    store = Prism::Cache::MemoryStore.new(max_size: 2)
+    store.write('a', 1)
+    store.write('b', 2)
+    store.write('c', 3)
+    assert_equal 2, store.size
+    assert_nil store.read('a')
+    assert_equal 2, store.read('b')
+    assert_equal 3, store.read('c')
+  end
+
+  def test_reading_a_key_protects_it_from_eviction
+    store = Prism::Cache::MemoryStore.new(max_size: 2)
+    store.write('a', 1)
+    store.write('b', 2)
+    store.read('a') # bump 'a' to most-recently-used, 'b' is now the LRU one
+    store.write('c', 3)
+    assert_equal 1, store.read('a')
+    assert_nil store.read('b')
+    assert_equal 3, store.read('c')
+  end
+
+  def test_rewriting_an_existing_key_does_not_grow_the_store
+    store = Prism::Cache::MemoryStore.new(max_size: 2)
+    store.write('a', 1)
+    store.write('b', 2)
+    store.write('a', 'updated')
+    assert_equal 2, store.size
+    assert_equal 'updated', store.read('a')
+    assert_equal 2, store.read('b')
+  end
+end