Add before_each, after_each for async tests. (#350)

Also add sample tests using them.

Author: ipod825

lua/plenary/async/init.lua

@@ -36,6 +36,8 @@ exports.tests.add_globals = function()
   a.describe = exports.tests.describe
   -- must prefix with a or stack overflow
   a.it = exports.tests.it
+  a.before_each = exports.tests.before_each
+  a.after_each = exports.tests.after_each
 end
 
 exports.tests.add_to_env = function()
@@ -50,6 +52,8 @@ exports.tests.add_to_env = function()
   env.a.describe = exports.tests.describe
   -- must prefix with a or stack overflow
   env.a.it = exports.tests.it
+  a.before_each = exports.tests.before_each
+  a.after_each = exports.tests.after_each
 
   setfenv(2, env)
 end

lua/plenary/async/tests.lua

@@ -10,4 +10,12 @@ M.it = function(s, async_func)
   it(s, util.will_block(async_func))
 end
 
+M.before_each = function(async_func)
+  before_each(util.will_block(async_func))
+end
+
+M.after_each = function(async_func)
+  after_each(util.will_block(async_func))
+end
+
 return M

tests/plenary/async/test_spec.lua

@@ -0,0 +1,52 @@
+require("plenary.async").tests.add_to_env()
+
+a.describe("a.before_each", function()
+  local counter = 0
+
+  local set_counter_to_one = a.wrap(function(callback)
+    a.util.sleep(5)
+    counter = 1
+  end, 1)
+
+  a.before_each(a.void(function()
+    set_counter_to_one()
+  end))
+
+  a.it("should run in async context", function()
+    counter = counter + 1
+    assert.are.same(counter, 2)
+  end)
+
+  a.it("should run for all tests", function()
+    counter = counter + 2
+    assert.are.same(counter, 3)
+  end)
+end)
+
+a.describe("a.after_each", function()
+  local counter = 0
+
+  local set_counter_to_one = a.wrap(function(callback)
+    a.util.sleep(5)
+    counter = 1
+  end, 1)
+
+  a.after_each(a.void(function()
+    set_counter_to_one()
+  end))
+
+  a.it("should not run before first test", function()
+    counter = counter + 1
+    assert.are.same(counter, 1)
+  end)
+
+  a.it("should run before the second test", function()
+    counter = counter + 2
+    assert.are.same(counter, 3)
+  end)
+
+  a.it("should run before the third test", function()
+    counter = counter + 3
+    assert.are.same(counter, 4)
+  end)
+end)