-- Parser checks for lib/data.lua.
-- Run from the repo root:  lua test/test_data.lua
-- Parsers are what break silently on a kernel or hardware change, so they are
-- what gets a test. Everything else in this project is verified by screenshot.

package.path = './?.lua;' .. package.path
local data = require 'lib.data'

local function read(path)
  local f = assert(io.open(path, 'r'))
  local s = f:read('*a')
  f:close()
  return s
end

-- cpu_times: total and idle jiffies from the aggregate "cpu " line.
local total, idle = data.cpu_times(read('test/fixtures/proc_stat'))
-- 209094+2199+135469+11604898+24408+0+946 = 11977014
assert(total == 11977014, 'cpu total, got ' .. tostring(total))
-- idle field is the 4th value, 11604898; iowait (24408) counts as idle too
assert(idle == 11629306, 'cpu idle, got ' .. tostring(idle))

-- mem_info: values in kB, as the file gives them.
local mem = data.mem_info(read('test/fixtures/proc_meminfo'))
assert(mem.total == 31943076, 'mem total, got ' .. tostring(mem.total))
assert(mem.available == 25627088, 'mem available, got ' .. tostring(mem.available))
-- used is total minus available, which is what a user means by "used"
assert(mem.used == 6315988, 'mem used, got ' .. tostring(mem.used))

-- millidegrees: hwmon temp*_input is millidegrees C, rounded to whole degrees.
assert(data.millidegrees(read('test/fixtures/temp1_input')) == 53,
  'temp, got ' .. tostring(data.millidegrees(read('test/fixtures/temp1_input'))))
-- A missing or unreadable sensor must yield nil, not an error and not 0:
-- 0 degrees is a plausible reading and would be indistinguishable from failure.
assert(data.millidegrees(nil) == nil, 'nil input must give nil')
assert(data.millidegrees('') == nil, 'empty input must give nil')
assert(data.millidegrees('garbage') == nil, 'unparseable input must give nil')

-- cpu_percent is a delta between two samples, so it holds state.
-- The first call has no previous sample and must report nil, not a number:
-- any number it invented would be wrong, and 100% on startup looks like a
-- real spike.
local c = data.new_cpu_counter()
assert(c:sample(1000, 900) == nil, 'first sample must give nil')

-- Second sample: 100 more total jiffies, 50 of them idle, so 50% busy.
-- Held in a local first: calling sample() again inside the assert message would
-- advance the counter a third time.
local busy = c:sample(1100, 950)
assert(busy == 50.0, 'second sample, got ' .. tostring(busy))

-- A counter that did not advance means no elapsed time, not 0% load.
local c2 = data.new_cpu_counter()
c2:sample(1000, 900)
assert(c2:sample(1000, 900) == nil, 'zero delta must give nil, not a division by zero')

print('test_data: all assertions passed')