Add more tests.

bin/t

@@ -1,2 +1,2 @@
 #!/bin/bash
-luatest
+luatest $@

tests/test_application.lua

@@ -0,0 +1,84 @@
+local assert = require "luassert"
+local spy = require "luassert.spy"
+
+local Application = require "atlas.application"
+local Response = require "atlas.response"
+local Route = require "atlas.route"
+local asgi = require "atlas.test.asgi"
+
+local tests = {}
+
+-- Application constructs an instance
+function tests.test_constructor()
+  local routes = {}
+  local app = Application(routes)
+
+  assert.equal(getmetatable(app), Application)
+  assert.is_not_nil(app.router)
+end
+
+-- Application is callable
+function tests.test_callable()
+  local app = Application({})
+  local receive = function() end
+  local called = false
+  local send = function() called = true end
+
+  app(asgi.make_scope(), receive, send)
+
+  assert.is_true(called)
+end
+
+-- Application handles a full match
+function tests.test_full_match()
+  local routes = {Route("/", function() return Response() end)}
+  local app = Application(routes)
+  local receive = function() end
+  local send = spy.new(function() end)
+
+  app(asgi.make_scope(), receive, send)
+
+  assert.spy(send).called_with({
+    type = "http.response.start",
+    status = 200,
+    headers = {{"content-type", "text/html"}},
+  })
+end
+
+-- Application handles a partial match
+function tests.test_partial_match()
+  local routes = {Route("/", function() end)}
+  local app = Application(routes)
+  local scope = asgi.make_scope()
+  scope.method = "POST"
+  local receive = function() end
+  local send = spy.new(function() end)
+
+  app(scope, receive, send)
+
+  assert.spy(send).called_with({
+    type = "http.response.start",
+    status = 405,
+    headers = {{"content-type", "text/html"}},
+  })
+end
+
+-- Application handles a none match
+function tests.test_none_match()
+  local routes = {Route("/asdf", function() end)}
+  local app = Application(routes)
+  local scope = asgi.make_scope()
+  scope.method = "POST"
+  local receive = function() end
+  local send = spy.new(function() end)
+
+  app(scope, receive, send)
+
+  assert.spy(send).called_with({
+    type = "http.response.start",
+    status = 404,
+    headers = {{"content-type", "text/html"}},
+  })
+end
+
+return tests