From 8ee7af4f580bb62854a326009ed312759ae50b83 Mon Sep 17 00:00:00 2001
From: Jason Thomas <jmthomas@ball.com>
Date: Wed, 24 Jun 2020 23:30:30 -0600
Subject: [PATCH] Fix XADD maxlen 0 (#192)

* XADD maxlen 0 creates empty stream

* Rubocop

* Ignore emptry streams on cleanup
---
 lib/mock_redis/stream.rb          |  6 +++++-
 lib/mock_redis/utility_methods.rb |  2 +-
 spec/commands/del_spec.rb         | 15 +++++++++++++++
 spec/commands/xadd_spec.rb        |  7 +++++++
 4 files changed, 28 insertions(+), 2 deletions(-)

diff --git a/lib/mock_redis/stream.rb b/lib/mock_redis/stream.rb
index 05b3f269..5cce8298 100644
--- a/lib/mock_redis/stream.rb
+++ b/lib/mock_redis/stream.rb
@@ -37,7 +37,11 @@ def add(id, values)
     def trim(count)
       deleted = @members.size - count
       if deleted > 0
-        @members = @members.to_a[-count..-1].to_set
+        @members = if count == 0
+                     Set.new
+                   else
+                     @members.to_a[-count..-1].to_set
+                   end
         deleted
       else
         0
diff --git a/lib/mock_redis/utility_methods.rb b/lib/mock_redis/utility_methods.rb
index 4e7238b4..47f18493 100644
--- a/lib/mock_redis/utility_methods.rb
+++ b/lib/mock_redis/utility_methods.rb
@@ -18,7 +18,7 @@ def primitive?(value)
     end
 
     def clean_up_empties_at(key)
-      if data[key]&.empty? && data[key] != ''
+      if data[key]&.empty? && data[key] != '' && !data[key].is_a?(Stream)
         del(key)
       end
     end
diff --git a/spec/commands/del_spec.rb b/spec/commands/del_spec.rb
index 27b15daa..36816314 100644
--- a/spec/commands/del_spec.rb
+++ b/spec/commands/del_spec.rb
@@ -1,6 +1,14 @@
 require 'spec_helper'
 
 describe '#del(key [, key, ...])' do
+  before :all do
+    sleep 1 - (Time.now.to_f % 1)
+  end
+
+  before :each do
+    @redises._gsub(/\d{3}-\d/, '...-.')
+  end
+
   it 'returns the number of keys deleted' do
     @redises.set('mock-redis-test:1', 1)
     @redises.set('mock-redis-test:2', 1)
@@ -32,4 +40,11 @@
   it 'raises an error if an empty array is given' do
     expect { @redises.del [] }.to raise_error Redis::CommandError
   end
+
+  it 'removes a stream key' do
+    @redises.xadd('mock-redis-stream', { key: 'value' }, maxlen: 0)
+    expect(@redises.exists?('mock-redis-stream')).to eq true
+    @redises.del('mock-redis-stream')
+    expect(@redises.exists?('mock-redis-stream')).to eq false
+  end
 end
diff --git a/spec/commands/xadd_spec.rb b/spec/commands/xadd_spec.rb
index 14f2336e..5e204779 100644
--- a/spec/commands/xadd_spec.rb
+++ b/spec/commands/xadd_spec.rb
@@ -112,4 +112,11 @@
       ]
     )
   end
+
+  it 'creates an empty stream with maxlen of 0' do
+    @redises.xadd(@key, { key: 'value' }, maxlen: 0)
+    expect(@redises.xlen(@key)).to eq 0
+    expect(@redises.xrange(@key, '-', '+')).to eq([])
+    expect(@redises.exists?(@key)).to eq true
+  end
 end