Add Use Specific Cache Store In A Single Test as an RSpec til

rspec/use-specific-cache-store-in-a-single-test.md

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+# Use Specific Cache Store In A Single Test
+
+It is generally recommended to use `:null_store` as the default cache store
+across your test suite. This is defined in `config/environments/test.rb`.
+
+```ruby
+  config.cache_store = :null_store
+```
+
+This generally simplifies tests by avoiding confusing stateful scenarios.
+
+If there is a test where you want to observe specific caching behavior, then
+you'll need to temporarily swap that for another store.
+
+One way to do that is by mocking the cache with `MemoryStore` in a before
+block.
+
+```ruby
+describe '#caching_feature' do
+  # use MemoryStore cache for these tests
+  before do
+    allow(Rails)
+      .to receive(:cache)
+      .and_return(ActiveSupport::Cache::MemoryStore.new)
+  end
+
+  it 'does caching' do
+    thing = Thing.caching_feature(1)
+
+    expect(thing.value).to eq true
+
+    thing.update(value: false)
+
+    thing = Thing.caching_feature(1)
+
+    expect(thing.value).to eq true
+  end
+end
+```
+
+[source](https://makandracards.com/makandra/46189-how-to-rails-cache-for-individual-rspec-tests)