Autorequire luatest in server instances

Luatest module available without explicit require.

```
g.server:exec(function()
   t.assert(...)
end)
```

The module is also available for the eval method:

```
g.server:eval([[ t.assert(...) ]])
```

This also works with replica set instances.

Note: This will work if the value for the LUA_PATH environment
variable has been set correctly. If it is wrong or undefined,
you will see a warning:

```
LUA_PATH is unset or incorrect, module 'luatest' not found
```

Resolves #233

Author: Oleg Chaplashkin

.luacheckrc

@@ -1,4 +1,6 @@
 include_files = {"**/*.lua", "*.rockspec", "*.luacheckrc"}
 exclude_files = {"lua_modules/", ".luarocks/", ".rocks/", "tmp/"}
 
+globals = {"t"}
+
 max_line_length = 120

CHANGELOG.md

@@ -41,6 +41,7 @@
 - Print Tarantool version used by luatest.
 - Add new module `replica_proxy.lua`.
 - Add new module `tarantool.lua`.
+- Autorequire `luatest` module in the server instance as `t` variable.
 
 ## 0.5.7
 

luatest/init.lua

@@ -95,4 +95,8 @@ function luatest.defaults(...)
     return luatest.configure(...)
 end
 
+if not rawget(_G, 't') then
+    rawset(_G, 't', luatest)
+end
+
 return luatest

luatest/server.lua

@@ -472,15 +472,25 @@ end
 
 --- Evaluate Lua code on the server.
 --
--- This is a shortcut for `server.net_box:eval()`.
+-- This is a wrapper for `server.net_box:eval()`.
 -- @string code
 -- @tab[opt] args
 -- @tab[opt] options
-function Server:eval(...)
+function Server:eval(code, ...)
     if self.net_box == nil then
         error('net_box is not connected', 2)
     end
-    return self.net_box:eval(...)
+    local preamble = [[
+        if not rawget(_G, 't') then
+            local is_ok, _t = pcall(require, 'luatest')
+            if is_ok then
+                rawset(_G, 't', _t)
+            else
+                require('log').warn('LUA_PATH is unset or incorrect, ' .. _t)
+            end
+        end
+    ]]
+    return self.net_box:eval(preamble .. code, ...)
 end
 
 --- Call remote function on the server by name.
@@ -526,7 +536,7 @@ end
 --    -- sum == 3
 --
 --    server:exec(function()
---        local t = require('luatest')
+--        -- luatest is always available as `t`
 --        t.assert_equals(math.pi, 3)
 --    end)
 --    -- mytest.lua:12: expected: 3, actual: 3.1415926535898
@@ -546,7 +556,7 @@ function Server:exec(fn, args, options)
         error(err, 2)
     end
 
-    return exec_tail(self.net_box:eval([[
+    return exec_tail(self:eval([[
         local dump, args = ...
         local fn = loadstring(dump)
         if args == nil then

test/autorequire_luatest_test.lua

@@ -0,0 +1,116 @@
+local fio = require('fio')
+
+local g = t.group()
+local Server = t.Server
+
+local root = fio.dirname(fio.dirname(fio.abspath(package.search('test.helper'))))
+local datadir = fio.pathjoin(root, 'tmp', 'luatest_module')
+local command = fio.pathjoin(root, 'test', 'server_instance.lua')
+
+g.before_all(function()
+    fio.rmtree(datadir)
+
+    g.server = Server:new({
+        command = command,
+        workdir = fio.pathjoin(datadir, 'common'),
+        env = {
+            LUA_PATH =
+                root .. '/?.lua;' ..
+                root .. '/?/init.lua;' ..
+                root .. '/.rocks/share/tarantool/?.lua'
+        },
+        http_port = 8182,
+        net_box_port = 3133,
+    })
+    fio.mktree(g.server.workdir)
+
+    g.server:start()
+    t.helpers.retrying({timeout = 2}, function()
+        g.server:http_request('get', '/ping')
+    end)
+
+    g.server:connect_net_box()
+end)
+
+g.after_all(function()
+    g.server:stop()
+    fio.rmtree(datadir)
+end)
+
+g.test_exec_without_t = function()
+    local actual = g.server:exec(function()
+        return 1 + 1
+    end)
+    t.assert_equals(actual, 2)
+end
+
+g.test_exec_with_global_variable = function()
+    g.server:exec(function()
+        t.assert_equals(1, 1)
+    end)
+    t.assert_equals(1, 1)
+end
+
+g.test_exec_with_local_variable = function()
+    g.server:exec(function()
+        local t = require('luatest')
+        t.assert_equals(1, 1)
+    end)
+    t.assert_equals(1, 1)
+end
+
+g.test_exec_with_local_duplicate = function()
+    g.server:exec(function()
+        local tt = require('luatest')
+        t.assert_equals(1, 1)
+        tt.assert_equals(1, 1)
+        t.assert_equals(tt, t)
+    end)
+end
+
+g.test_eval_with_t = function()
+    local actual = g.server:eval([[
+        t.assert_equals(1, 1)
+        return 1
+    ]])
+    t.assert_equals(actual, 1)
+end
+
+g.before_test('test_exec_when_lua_path_is_unset', function()
+    -- Setup custom server without LUA_PATH variable
+    local workdir = fio.tempdir()
+    local log = fio.pathjoin(workdir, 'bad_env_server.log')
+    g.bad_env_server = Server:new({
+        command = command,
+        workdir = workdir,
+        env = {
+            TARANTOOL_LOG = log
+        },
+        http_port = 8183,
+        net_box_port = 3134,
+    })
+
+    fio.mktree(g.bad_env_server.workdir)
+
+    g.bad_env_server:start()
+
+    t.helpers.retrying({timeout = 2}, function()
+        g.bad_env_server:http_request('get', '/ping')
+    end)
+
+    g.bad_env_server:connect_net_box()
+end)
+
+g.test_exec_when_lua_path_is_unset = function()
+    g.bad_env_server:exec(function() return 1 + 1 end)
+
+    t.assert(
+        g.bad_env_server:grep_log(
+            "W> LUA_PATH is unset or incorrect, module 'luatest' not found"
+        )
+    )
+end
+
+g.after_test('test_exec_when_lua_path_is_unset', function()
+    g.bad_env_server:drop()
+end)

test/server_instance.lua

@@ -5,12 +5,14 @@ local json = require('json')
 local workdir = os.getenv('TARANTOOL_WORKDIR')
 local listen = os.getenv('TARANTOOL_LISTEN')
 local http_port = os.getenv('TARANTOOL_HTTP_PORT')
+local log = os.getenv('TARANTOOL_LOG')
 
-box.cfg({work_dir = workdir})
+local httpd = require('http.server').new('0.0.0.0', http_port)
+
+box.cfg({work_dir = workdir, log = log})
 box.schema.user.grant('guest', 'super', nil, nil, {if_not_exists=true})
 box.cfg({listen = listen})
 
-local httpd = require('http.server').new('0.0.0.0', http_port)
 
 httpd:route({path = '/ping', method = 'GET'}, function()
     return {status = 200, body = 'pong'}