tests/lapi: os tests

The patch adds tests for the functions in os library except the
following functions: `os.tmpname`, `os.rename`, `os.remove`,
`os.execute`, `os.clock`.

Author: ligurio

tests/lapi/os_date_test.lua

@@ -0,0 +1,34 @@
+--[=[[
+SPDX-License-Identifier: ISC
+Copyright (c) 2023-2025, Sergey Bronnikov.
+
+6.9 – Operating System Facilities
+https://www.lua.org/manual/5.3/manual.html#6.9
+
+LuaJIT 2.1 VM out of memory for `os.date`,
+https://github.com/LuaJIT/LuaJIT/issues/463
+
+Checking a format for os.date may read pass the format string,
+https://www.lua.org/bugs.html#5.3.3-2
+
+os.date throws an error when result is the empty string,
+https://www.lua.org/bugs.html#5.1.1-4
+
+Synopsis: os.date([format [, time]])
+]]=]
+
+local luzer = require("luzer")
+local test_lib = require("lib")
+
+local function TestOneInput(buf)
+    local fdp = luzer.FuzzedDataProvider(buf)
+    os.setlocale(test_lib.random_locale(fdp), "all")
+    local format = fdp:consume_string(test_lib.MAX_STR_LEN)
+    local time = fdp:consume_number(test_lib.MIN_INT, test_lib.MAX_INT)
+    os.date(format, time)
+end
+
+local args = {
+    artifact_prefix = "os_date_",
+}
+luzer.Fuzz(TestOneInput, nil, args)

tests/lapi/os_difftime_test.lua

@@ -0,0 +1,27 @@
+--[[
+SPDX-License-Identifier: ISC
+Copyright (c) 2023-2025, Sergey Bronnikov.
+
+6.9 – Operating System Facilities
+https://www.lua.org/manual/5.3/manual.html#6.9
+
+Synopsis: os.difftime(t2, t1)
+]]
+
+local luzer = require("luzer")
+local test_lib = require("lib")
+local MIN_INT = test_lib.MIN_INT64
+local MAX_INT = test_lib.MAX_INT64
+
+local function TestOneInput(buf)
+    local fdp = luzer.FuzzedDataProvider(buf)
+    local t1 = fdp:consume_number(MIN_INT, MAX_INT)
+    local t2 = fdp:consume_number(MIN_INT, MAX_INT)
+    local res = os.difftime(t1, t2)
+    assert(type(res) == "number")
+end
+
+local args = {
+    artifact_prefix = "os_difftime_",
+}
+luzer.Fuzz(TestOneInput, nil, args)

tests/lapi/os_getenv_test.lua

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+--[[
+SPDX-License-Identifier: ISC
+Copyright (c) 2023-2025, Sergey Bronnikov.
+
+6.9 – Operating System Facilities
+https://www.lua.org/manual/5.3/manual.html#6.9
+
+Synopsis: os.getenv(varname)
+]]
+
+
+local luzer = require("luzer")
+
+local function TestOneInput(buf)
+    local v = os.getenv(buf)
+    assert(type(v) == "string" or v == nil)
+end
+
+local args = {
+    artifact_prefix = "os_getenv_",
+}
+luzer.Fuzz(TestOneInput, nil, args)

tests/lapi/os_setlocale_test.lua

@@ -0,0 +1,28 @@
+--[[
+SPDX-License-Identifier: ISC
+Copyright (c) 2023-2025, Sergey Bronnikov.
+
+6.9 – Operating System Facilities
+https://www.lua.org/manual/5.3/manual.html#6.9
+
+Synopsis: os.setlocale(locale [, category])
+]]
+
+local luzer = require("luzer")
+local test_lib = require("lib")
+
+local function TestOneInput(buf)
+    local fdp = luzer.FuzzedDataProvider(buf)
+    local locale = fdp:consume_string(test_lib.MAX_STR_LEN)
+    local category = fdp:oneof({
+        "all", "collate", "ctype", "monetary", "numeric", "time",
+    })
+    local locale_string = os.setlocale(locale, category)
+    assert(type(locale_string) == "string" or
+	       locale_string == nil)
+end
+
+local args = {
+    artifact_prefix = "os_setlocale_",
+}
+luzer.Fuzz(TestOneInput, nil, args)

tests/lapi/os_time_test.lua

@@ -0,0 +1,34 @@
+--[[
+SPDX-License-Identifier: ISC
+Copyright (c) 2023-2025, Sergey Bronnikov.
+
+6.9 – Operating System Facilities
+https://www.lua.org/manual/5.3/manual.html#6.9
+
+Synopsis: os.time([table])
+]]
+
+local luzer = require("luzer")
+local test_lib = require("lib")
+local MAX_INT64 = test_lib.MAX_INT64
+local MIN_INT64 = test_lib.MIN_INT64
+
+local function TestOneInput(buf)
+    local fdp = luzer.FuzzedDataProvider(buf)
+    os.setlocale(test_lib.random_locale(fdp), "all")
+    local time = {
+        day = fdp:consume_number(MIN_INT64, MAX_INT64),
+        hour = fdp:consume_number(MIN_INT64, MAX_INT64),
+        isdst = fdp:consume_boolean(),
+        min = fdp:consume_number(MIN_INT64, MAX_INT64),
+        month = fdp:consume_number(MIN_INT64, MAX_INT64),
+        sec = fdp:consume_number(MIN_INT64, MAX_INT64),
+        year = fdp:consume_number(MIN_INT64, MAX_INT64),
+    }
+    os.time(time)
+end
+
+local args = {
+    artifact_prefix = "os_time_",
+}
+luzer.Fuzz(TestOneInput, nil, args)