How to generate Lua coverage report for built in module?

Assumption

Assumption is that you are running normal out-of-tree build, and current directory is used build/ directory, not from inside of repository tree root. If you got used to using in-source tree - please update links below accordingly.

SYNOPSIS

./src/tarantool -lluacov ../test/app-tap/datetime.test.lua
luacov builtin/datetime.lua
tail -10 luacov.report.out

Detailed approach

As a first, preparation step you need to install luacov somewhere, where tarantool will be able to find it. The simplest approach would be to use tarantoolctl rocks install luacov which would install luacov to the local .rocks directory, where Tarantool would automatically find it.

13:53 $ tarantoolctl rocks list

Installed rocks:
----------------

argparse
   0.6.0-1 (installed) - /home/tsafin/datetime/tarantoolt/build/.rocks/share/tarantool/rocks

luacov
   0.13.0-1 (installed) - /home/tsafin/datetime/tarantoolt/build/.rocks/share/tarantool/rocks

luafilesystem
   1.7.0-2 (installed) - /home/tsafin/datetime/tarantoolt/build/.rocks/share/tarantool/rocks

Then you need to run your test with luacov module activated (see -lluacov in the command-line):

13:57 $ ./src/tarantool -lluacov ../test/app-tap/datetime.test.lua | head -10
TAP version 13
1..11
    # Default date creation
    1..9
    ok - T.epoch ==0
    ok - T.nsec == 0
    ok - T.tzoffset == 0
    ok - tostring(T1)
    ok - T.epoch ==0
    ok - T.nsec == 0

This invocation creates luacov.stat.out of a strange format:

15:39 $ grep -A1 datetime.lua luacov.stats.out
619:builtin/datetime.lua
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
118 0 0 0 232 0 0 0 116 0 0 48 0 0 48 0 0 81 0 0 0 81 0 0 0 0 0 164 140 0 0 24 
30 15 0 18 9 0 0 0 0 2 2 2 0 2 0 0 0 0 63 0 0 0 0 120 0 0 0 7 0 0 0 0 0 0 0 189 
0 0 0 13 0 0 0 13 0 0 0 3 0 0 1 1 0 0 0 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 
0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 9 9 9 6 0 3 0 0 0 36 36 36 36 36 36 0 0 0 33 33 
0 0 0 17 8 9 9 0 0 0 0 234 0 0 0 0 53 3 0 50 0 0 0 50 50 50 0 50 50 26 26 0 50 
50 25 25 0 50 50 27 24 0 47 47 17 17 0 47 47 16 16 0 47 47 15 15 0 0 47 141 94 
47 4 0 43 2 41 2 0 43 43 14 3 0 11 3 0 8 8 0 0 8 2 6 6 3 0 5 0 0 34 34 8 4 0 0 
...

You might recognize, that instead of path to the module file, we see builtin/datetime.lua and if luacov reporter would use this path for report annotation, it would not find file, and would fail to report anything.

~/tarantool/build>
15:39 $ luacov builtin/datetime.lua
Couldn't open builtin/datetime.lua: No such file or directory

We could solve it 2 ways:

• update paths in luacov.stats.out to use relative path to original filename, i.e. instead of builtin/datetime.lua to point to ../src/lua/datetime.lua;
• or simply create symbolic link in the directory builtin which would redirect to that file via relative path.

• 1st approach is sort of fragile - you would need to update luacov.stats.out after each luacov stats update.

• 2nd approach is more convenient, IMHO, unless you intentionally cleaned up current directory, and removed builtin/ subdirectory, this created symbolic link will continue work. Thus I recommend to use it:

15:41 $ ls -al ../src/lua/datetime.lua
-rw-r--r-- 1 tsafin tsafin 16968 Sep 28 13:56 ../src/lua/datetime.lua
~/tarantool/build>

15:42 $ mkdir builtin
~/tarantool/build>

15:45 $ cd builtin/
~/tarantool/build/builtin>

15:45 $ ln -s ../../src/lua/datetime.lua datetime.lua
~/tarantool/build/builtin>

15:45 $ cd -
/home/tsafin/datetime/tarantoolt/build

~/tarantool/build>
15:45 $ luacov builtin/datetime.lua

NB! If you do not have luacov installed globally, then it's available under local '.rocks directory, and you could run it this way ./src/tarantool .rocks/share/tarantool/rocks/luacov/0.13.0-1/bin/luacov builtin/datetime.lua

After these steps luacov report is generated in the current directory under name luacov.report.out

15:46 $ tail -10 luacov.report.out

==============================================================================
Summary
==============================================================================

File                 Hits Missed Coverage
-----------------------------------------
builtin/datetime.lua 245  39     86.27%
-----------------------------------------
Total                245  39     86.27%