Merge #22325 vim.version semver parser

7 files changed, 693 insertions, 16 deletions

diff --git a/runtime/doc/lua.txt b/runtime/doc/lua.txt
index 1eb5ab41e6..697cd86e8a 100644
--- a/runtime/doc/lua.txt
+++ b/runtime/doc/lua.txt
@@ -2497,4 +2497,71 @@ trust({opts})                                             *vim.secure.trust()*
         • true and full path of target file if operation was successful
         • false and error message on failure
 
+
+==============================================================================
+Lua module: version                                              *lua-version*
+
+cmp({v1}, {v2}, {opts})                                    *vim.version.cmp()*
+    Compares two strings ( `v1` and `v2` ) in semver format.
+
+    Parameters: ~
+      • {v1}    (string) Version.
+      • {v2}    (string) Version to compare with v1.
+      • {opts}  (table|nil) Optional keyword arguments:
+                • strict (boolean): see `semver.parse` for details. Defaults
+                  to false.
+
+    Return: ~
+        (integer) `-1` if `v1 < v2`, `0` if `v1 == v2`, `1` if `v1 > v2`.
+
+eq({v1}, {v2})                                              *vim.version.eq()*
+    Returns `true` if `v1` are `v2` are equal versions.
+
+    Parameters: ~
+      • {v1}  (string)
+      • {v2}  (string)
+
+    Return: ~
+        (boolean)
+
+gt({v1}, {v2})                                              *vim.version.gt()*
+    Returns `true` if `v1` is greater than `v2` .
+
+    Parameters: ~
+      • {v1}  (string)
+      • {v2}  (string)
+
+    Return: ~
+        (boolean)
+
+lt({v1}, {v2})                                              *vim.version.lt()*
+    Returns `true` if `v1` is less than `v2` .
+
+    Parameters: ~
+      • {v1}  (string)
+      • {v2}  (string)
+
+    Return: ~
+        (boolean)
+
+parse({version}, {opts})                                 *vim.version.parse()*
+    Parses a semantic version string.
+
+    Ignores leading "v" and surrounding whitespace, e.g. "
+    v1.0.1-rc1+build.2", "1.0.1-rc1+build.2", "v1.0.1-rc1+build.2" and
+    "v1.0.1-rc1+build.2 " are all parsed as: >
+
+       { major = 1, minor = 0, patch = 1, prerelease = "rc1", build = "build.2" }
+<
+
+    Parameters: ~
+      • {version}  (string) Version string to be parsed.
+      • {opts}     (table|nil) Optional keyword arguments:
+                   • strict (boolean): Default false. If `true` , no coercion is attempted on input not strictly
+                     conforming to semver v2.0.0 ( https://semver.org/spec/v2.0.0.html ). E.g. `parse("v1.2")` returns nil.
+
+    Return: ~
+        (table|nil) parsed_version Parsed version table or `nil` if `version`
+        is invalid.
+
  vim:tw=78:ts=8:sw=4:sts=4:et:ft=help:norl:
diff --git a/runtime/doc/news.txt b/runtime/doc/news.txt
index 415195e27e..28fdaa770d 100644
--- a/runtime/doc/news.txt
+++ b/runtime/doc/news.txt
@@ -55,6 +55,9 @@ NEW FEATURES                                                    *news-features*
 
 The following new APIs or features were added.
 
+• Added |vim.version| for parsing and comparing version strings conforming to
+  the semver specification, see |lua-version|.
+
 • A new environment variable named NVIM_APPNAME enables configuring the
   directories where Neovim should find its configuration and state files. See
   `:help $NVIM_APPNAME` .
diff --git a/runtime/lua/vim/_init_packages.lua b/runtime/lua/vim/_init_packages.lua
index e3a442af5e..57c0fc9122 100644
--- a/runtime/lua/vim/_init_packages.lua
+++ b/runtime/lua/vim/_init_packages.lua
@@ -51,7 +51,10 @@ end
 -- builtin functions which always should be available
 require('vim.shared')
 
-vim._submodules = { inspect = true }
+vim._submodules = {
+  inspect = true,
+  version = true,
+}
 
 -- These are for loading runtime modules in the vim namespace lazily.
 setmetatable(vim, {
diff --git a/runtime/lua/vim/version.lua b/runtime/lua/vim/version.lua
new file mode 100644
index 0000000000..35629c461f
--- /dev/null
+++ b/runtime/lua/vim/version.lua
@@ -0,0 +1,277 @@
+local M = {}
+
+---@private
+---@param version string
+---@return string
+local function create_err_msg(v)
+  if type(v) == 'string' then
+    return string.format('invalid version: "%s"', tostring(v))
+  end
+  return string.format('invalid version: %s (%s)', tostring(v), type(v))
+end
+
+---@private
+--- Throws an error if `version` cannot be parsed.
+---@param version string
+local function assert_version(version, opt)
+  local rv = M.parse(version, opt)
+  if rv == nil then
+    error(create_err_msg(version))
+  end
+  return rv
+end
+
+---@private
+--- Compares the prerelease component of the two versions.
+local function cmp_prerelease(v1, v2)
+  if v1.prerelease and not v2.prerelease then
+    return -1
+  end
+  if not v1.prerelease and v2.prerelease then
+    return 1
+  end
+  if not v1.prerelease and not v2.prerelease then
+    return 0
+  end
+
+  local v1_identifiers = vim.split(v1.prerelease, '.', { plain = true })
+  local v2_identifiers = vim.split(v2.prerelease, '.', { plain = true })
+  local i = 1
+  local max = math.max(vim.tbl_count(v1_identifiers), vim.tbl_count(v2_identifiers))
+  while i <= max do
+    local v1_identifier = v1_identifiers[i]
+    local v2_identifier = v2_identifiers[i]
+    if v1_identifier ~= v2_identifier then
+      local v1_num = tonumber(v1_identifier)
+      local v2_num = tonumber(v2_identifier)
+      local is_number = v1_num and v2_num
+      if is_number then
+        -- Number comparisons
+        if not v1_num and v2_num then
+          return -1
+        end
+        if v1_num and not v2_num then
+          return 1
+        end
+        if v1_num == v2_num then
+          return 0
+        end
+        if v1_num > v2_num then
+          return 1
+        end
+        if v1_num < v2_num then
+          return -1
+        end
+      else
+        -- String comparisons
+        if v1_identifier and not v2_identifier then
+          return 1
+        end
+        if not v1_identifier and v2_identifier then
+          return -1
+        end
+        if v1_identifier < v2_identifier then
+          return -1
+        end
+        if v1_identifier > v2_identifier then
+          return 1
+        end
+        if v1_identifier == v2_identifier then
+          return 0
+        end
+      end
+    end
+    i = i + 1
+  end
+
+  return 0
+end
+
+---@private
+local function cmp_version_core(v1, v2)
+  if v1.major == v2.major and v1.minor == v2.minor and v1.patch == v2.patch then
+    return 0
+  end
+  if
+    v1.major > v2.major
+    or (v1.major == v2.major and v1.minor > v2.minor)
+    or (v1.major == v2.major and v1.minor == v2.minor and v1.patch > v2.patch)
+  then
+    return 1
+  end
+  return -1
+end
+
+--- Compares two strings (`v1` and `v2`) in semver format.
+---@param v1 string Version.
+---@param v2 string Version to compare with v1.
+---@param opts table|nil Optional keyword arguments:
+---                      - strict (boolean):  see `semver.parse` for details. Defaults to false.
+---@return integer `-1` if `v1 < v2`, `0` if `v1 == v2`, `1` if `v1 > v2`.
+function M.cmp(v1, v2, opts)
+  opts = opts or { strict = false }
+  local v1_parsed = assert_version(v1, opts)
+  local v2_parsed = assert_version(v2, opts)
+
+  local result = cmp_version_core(v1_parsed, v2_parsed)
+  if result == 0 then
+    result = cmp_prerelease(v1_parsed, v2_parsed)
+  end
+  return result
+end
+
+---@private
+---@param labels string Prerelease and build component of semantic version string e.g. "-rc1+build.0".
+---@return string|nil
+local function parse_prerelease(labels)
+  -- This pattern matches "-(alpha)+build.15".
+  -- '^%-[%w%.]+$'
+  local result = labels:match('^%-([%w%.]+)+.+$')
+  if result then
+    return result
+  end
+  -- This pattern matches "-(alpha)".
+  result = labels:match('^%-([%w%.]+)')
+  if result then
+    return result
+  end
+
+  return nil
+end
+
+---@private
+---@param labels string Prerelease and build component of semantic version string e.g. "-rc1+build.0".
+---@return string|nil
+local function parse_build(labels)
+  -- Pattern matches "-alpha+(build.15)".
+  local result = labels:match('^%-[%w%.]+%+([%w%.]+)$')
+  if result then
+    return result
+  end
+
+  -- Pattern matches "+(build.15)".
+  result = labels:match('^%+([%w%.]+)$')
+  if result then
+    return result
+  end
+
+  return nil
+end
+
+---@private
+--- Extracts the major, minor, patch and preprelease and build components from
+--- `version`.
+---@param version string Version string
+local function extract_components_strict(version)
+  local major, minor, patch, prerelease_and_build = version:match('^v?(%d+)%.(%d+)%.(%d+)(.*)$')
+  return tonumber(major), tonumber(minor), tonumber(patch), prerelease_and_build
+end
+
+---@private
+--- Extracts the major, minor, patch and preprelease and build components from
+--- `version`. When `minor` and `patch` components are not found (nil), coerce
+--- them to 0.
+---@param version string Version string
+local function extract_components_loose(version)
+  local major, minor, patch, prerelease_and_build = version:match('^v?(%d+)%.?(%d*)%.?(%d*)(.*)$')
+  major = tonumber(major)
+  minor = tonumber(minor) or 0
+  patch = tonumber(patch) or 0
+  return major, minor, patch, prerelease_and_build
+end
+
+---@private
+--- Validates the prerelease and build string e.g. "-rc1+build.0". If the
+--- prerelease, build or both are valid forms then it will return true, if it
+--- is not of any valid form, it will return false.
+---@param prerelease_and_build string
+---@return boolean
+local function is_prerelease_and_build_valid(prerelease_and_build)
+  if prerelease_and_build == '' then
+    return true
+  end
+  local has_build = parse_build(prerelease_and_build) ~= nil
+  local has_prerelease = parse_prerelease(prerelease_and_build) ~= nil
+  local has_prerelease_and_build = has_prerelease and has_build
+  return has_build or has_prerelease or has_prerelease_and_build
+end
+
+--- Parses a semantic version string.
+---
+--- Ignores leading "v" and surrounding whitespace, e.g. " v1.0.1-rc1+build.2",
+--- "1.0.1-rc1+build.2", "v1.0.1-rc1+build.2" and "v1.0.1-rc1+build.2 " are all parsed as:
+--- <pre>
+---   { major = 1, minor = 0, patch = 1, prerelease = "rc1", build = "build.2" }
+--- </pre>
+---
+---@param version string Version string to be parsed.
+---@param opts table|nil Optional keyword arguments:
+---                      - strict (boolean):  Default false. If `true`, no coercion is attempted on
+---                      input not strictly conforming to semver v2.0.0
+---                      (https://semver.org/spec/v2.0.0.html). E.g. `parse("v1.2")` returns nil.
+---@return table|nil parsed_version Parsed version table or `nil` if `version` is invalid.
+function M.parse(version, opts)
+  if type(version) ~= 'string' then
+    error(create_err_msg(version))
+  end
+
+  opts = opts or { strict = false }
+
+  version = vim.trim(version)
+
+  local extract_components = opts.strict and extract_components_strict or extract_components_loose
+  local major, minor, patch, prerelease_and_build = extract_components(version)
+
+  -- If major is nil then that means that the version does not begin with a
+  -- digit with or without a "v" prefix.
+  if major == nil or not is_prerelease_and_build_valid(prerelease_and_build) then
+    return nil
+  end
+
+  local prerelease = nil
+  local build = nil
+  if prerelease_and_build ~= nil then
+    prerelease = parse_prerelease(prerelease_and_build)
+    build = parse_build(prerelease_and_build)
+  end
+
+  return {
+    major = major,
+    minor = minor,
+    patch = patch,
+    prerelease = prerelease,
+    build = build,
+  }
+end
+
+---Returns `true` if `v1` are `v2` are equal versions.
+---@param v1 string
+---@param v2 string
+---@return boolean
+function M.eq(v1, v2)
+  return M.cmp(v1, v2) == 0
+end
+
+---Returns `true` if `v1` is less than `v2`.
+---@param v1 string
+---@param v2 string
+---@return boolean
+function M.lt(v1, v2)
+  return M.cmp(v1, v2) == -1
+end
+
+---Returns `true` if `v1` is greater than `v2`.
+---@param v1 string
+---@param v2 string
+---@return boolean
+function M.gt(v1, v2)
+  return M.cmp(v1, v2) == 1
+end
+
+setmetatable(M, {
+  __call = function()
+    return vim.fn.api_info().version
+  end,
+})
+
+return M
diff --git a/scripts/gen_vimdoc.py b/scripts/gen_vimdoc.py
index 0164278b34..1e85fa49e9 100755
--- a/scripts/gen_vimdoc.py
+++ b/scripts/gen_vimdoc.py
@@ -152,6 +152,7 @@ CONFIG = {
             'keymap.lua',
             'fs.lua',
             'secure.lua',
+            'version.lua',
         ],
         'files': [
             'runtime/lua/vim/_editor.lua',
@@ -162,6 +163,7 @@ CONFIG = {
             'runtime/lua/vim/keymap.lua',
             'runtime/lua/vim/fs.lua',
             'runtime/lua/vim/secure.lua',
+            'runtime/lua/vim/version.lua',
             'runtime/lua/vim/_inspector.lua',
         ],
         'file_patterns': '*.lua',
@@ -192,6 +194,7 @@ CONFIG = {
             'keymap': 'vim.keymap',
             'fs': 'vim.fs',
             'secure': 'vim.secure',
+            'version': 'vim.version',
         },
         'append_only': [
             'shared.lua',
diff --git a/src/nvim/lua/executor.c b/src/nvim/lua/executor.c
index bb461a7f13..5ec91aebb0 100644
--- a/src/nvim/lua/executor.c
+++ b/src/nvim/lua/executor.c
@@ -165,17 +165,6 @@ static int nlua_pcall(lua_State *lstate, int nargs, int nresults)
   return status;
 }
 
-/// Gets the version of the current Nvim build.
-///
-/// @param  lstate  Lua interpreter state.
-static int nlua_nvim_version(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
-{
-  Dictionary version = version_dict();
-  nlua_push_Dictionary(lstate, version, true);
-  api_free_dictionary(version);
-  return 1;
-}
-
 static void nlua_luv_error_event(void **argv)
 {
   char *error = (char *)argv[0];
@@ -739,10 +728,6 @@ static bool nlua_state_init(lua_State *const lstate) FUNC_ATTR_NONNULL_ALL
   // vim.types, vim.type_idx, vim.val_idx
   nlua_init_types(lstate);
 
-  // neovim version
-  lua_pushcfunction(lstate, &nlua_nvim_version);
-  lua_setfield(lstate, -2, "version");
-
   // schedule
   lua_pushcfunction(lstate, &nlua_schedule);
   lua_setfield(lstate, -2, "schedule");
diff --git a/test/functional/lua/version_spec.lua b/test/functional/lua/version_spec.lua
new file mode 100644
index 0000000000..b68727ca77
--- /dev/null
+++ b/test/functional/lua/version_spec.lua
@@ -0,0 +1,339 @@
+local helpers = require('test.functional.helpers')(after_each)
+local clear = helpers.clear
+local eq = helpers.eq
+local exec_lua = helpers.exec_lua
+local matches = helpers.matches
+local pcall_err = helpers.pcall_err
+
+local version = require('vim.version')
+
+local function quote_empty(s)
+  return tostring(s) == '' and '""' or tostring(s)
+end
+
+describe('version', function()
+  it('package', function()
+    clear()
+    eq({ major = 42, minor = 3, patch = 99 }, exec_lua("return vim.version.parse('v42.3.99')"))
+  end)
+
+  describe('cmp()', function()
+    local testcases = {
+      {
+        desc = '(v1 < v2)',
+        v1 = 'v0.0.99',
+        v2 = 'v9.0.0',
+        want = -1,
+      },
+      {
+        desc = '(v1 < v2)',
+        v1 = 'v0.4.0',
+        v2 = 'v0.9.99',
+        want = -1,
+      },
+      {
+        desc = '(v1 < v2)',
+        v1 = 'v0.2.8',
+        v2 = 'v1.0.9',
+        want = -1,
+      },
+      {
+        desc = '(v1 == v2)',
+        v1 = 'v0.0.0',
+        v2 = 'v0.0.0',
+        want = 0,
+      },
+      {
+        desc = '(v1 > v2)',
+        v1 = 'v9.0.0',
+        v2 = 'v0.9.0',
+        want = 1,
+      },
+      {
+        desc = '(v1 > v2)',
+        v1 = 'v0.9.0',
+        v2 = 'v0.0.0',
+        want = 1,
+      },
+      {
+        desc = '(v1 > v2)',
+        v1 = 'v0.0.9',
+        v2 = 'v0.0.0',
+        want = 1,
+      },
+      {
+        desc = '(v1 < v2) when v1 has prerelease',
+        v1 = 'v1.0.0-alpha',
+        v2 = 'v1.0.0',
+        want = -1,
+      },
+      {
+        desc = '(v1 > v2) when v2 has prerelease',
+        v1 = '1.0.0',
+        v2 = '1.0.0-alpha',
+        want = 1,
+      },
+      {
+        desc = '(v1 > v2) when v1 has a higher number identifier',
+        v1 = '1.0.0-2',
+        v2 = '1.0.0-1',
+        want = 1,
+      },
+      {
+        desc = '(v1 < v2) when v2 has a higher number identifier',
+        v1 = '1.0.0-2',
+        v2 = '1.0.0-9',
+        want = -1,
+      },
+      {
+        desc = '(v1 < v2) when v2 has more identifiers',
+        v1 = '1.0.0-2',
+        v2 = '1.0.0-2.0',
+        want = -1,
+      },
+      {
+        desc = '(v1 > v2) when v1 has more identifiers',
+        v1 = '1.0.0-2.0',
+        v2 = '1.0.0-2',
+        want = 1,
+      },
+      {
+        desc = '(v1 == v2) when v2 has same numeric identifiers',
+        v1 = '1.0.0-2.0',
+        v2 = '1.0.0-2.0',
+        want = 0,
+      },
+      {
+        desc = '(v1 == v2) when v2 has same alphabet identifiers',
+        v1 = '1.0.0-alpha',
+        v2 = '1.0.0-alpha',
+        want = 0,
+      },
+      {
+        desc = '(v1 < v2) when v2 has an alphabet identifier with higher ASCII sort order',
+        v1 = '1.0.0-alpha',
+        v2 = '1.0.0-beta',
+        want = -1,
+      },
+      {
+        desc = '(v1 > v2) when v1 has an alphabet identifier with higher ASCII sort order',
+        v1 = '1.0.0-beta',
+        v2 = '1.0.0-alpha',
+        want = 1,
+      },
+      {
+        desc = '(v1 < v2) when v2 has prerelease and number identifer',
+        v1 = '1.0.0-alpha',
+        v2 = '1.0.0-alpha.1',
+        want = -1,
+      },
+      {
+        desc = '(v1 > v2) when v1 has prerelease and number identifer',
+        v1 = '1.0.0-alpha.1',
+        v2 = '1.0.0-alpha',
+        want = 1,
+      },
+      {
+        desc = '(v1 > v2) when v1 has an additional alphabet identifier',
+        v1 = '1.0.0-alpha.beta',
+        v2 = '1.0.0-alpha',
+        want = 1,
+      },
+      {
+        desc = '(v1 < v2) when v2 has an additional alphabet identifier',
+        v1 = '1.0.0-alpha',
+        v2 = '1.0.0-alpha.beta',
+        want = -1,
+      },
+      {
+        desc = '(v1 < v2) when v2 has an a first alphabet identifier with higher precedence',
+        v1 = '1.0.0-alpha.beta',
+        v2 = '1.0.0-beta',
+        want = -1,
+      },
+      {
+        desc = '(v1 > v2) when v1 has an a first alphabet identifier with higher precedence',
+        v1 = '1.0.0-beta',
+        v2 = '1.0.0-alpha.beta',
+        want = 1,
+      },
+      {
+        desc = '(v1 < v2) when v2 has an additional number identifer',
+        v1 = '1.0.0-beta',
+        v2 = '1.0.0-beta.2',
+        want = -1,
+      },
+      {
+        desc = '(v1 < v2) when v2 has same first alphabet identifier but has a higher number identifer',
+        v1 = '1.0.0-beta.2',
+        v2 = '1.0.0-beta.11',
+        want = -1,
+      },
+      {
+        desc = '(v1 < v2) when v2 has higher alphabet precedence',
+        v1 = '1.0.0-beta.11',
+        v2 = '1.0.0-rc.1',
+        want = -1,
+      },
+    }
+    for _, tc in ipairs(testcases) do
+      it(
+        string.format('%d %s (v1 = %s, v2 = %s)', tc.want, tc.desc, tc.v1, tc.v2),
+        function()
+          eq(tc.want, version.cmp(tc.v1, tc.v2, { strict = true }))
+        end
+      )
+    end
+  end)
+
+  describe('parse()', function()
+    describe('strict=true', function()
+      local testcases = {
+        {
+          desc = 'version without leading "v"',
+          version = '10.20.123',
+          want = {
+            major = 10,
+            minor = 20,
+            patch = 123,
+            prerelease = nil,
+            build = nil,
+          },
+        },
+        {
+          desc = 'valid version with leading "v"',
+          version = 'v1.2.3',
+          want = { major = 1, minor = 2, patch = 3 },
+        },
+        {
+          desc = 'valid version with leading "v" and whitespace',
+          version = '  v1.2.3',
+          want = { major = 1, minor = 2, patch = 3 },
+        },
+        {
+          desc = 'valid version with leading "v" and trailing whitespace',
+          version = 'v1.2.3  ',
+          want = { major = 1, minor = 2, patch = 3 },
+        },
+        {
+          desc = 'version with prerelease',
+          version = '1.2.3-alpha',
+          want = { major = 1, minor = 2, patch = 3, prerelease = 'alpha' },
+        },
+        {
+          desc = 'version with prerelease with additional identifiers',
+          version = '1.2.3-alpha.1',
+          want = { major = 1, minor = 2, patch = 3, prerelease = 'alpha.1' },
+        },
+        {
+          desc = 'version with build',
+          version = '1.2.3+build.15',
+          want = { major = 1, minor = 2, patch = 3, build = 'build.15' },
+        },
+        {
+          desc = 'version with prerelease and build',
+          version = '1.2.3-rc1+build.15',
+          want = {
+            major = 1,
+            minor = 2,
+            patch = 3,
+            prerelease = 'rc1',
+            build = 'build.15',
+          },
+        },
+      }
+      for _, tc in ipairs(testcases) do
+        it(
+          string.format('for %q: version = %q', tc.desc, tc.version),
+          function()
+            eq(tc.want, version.parse(tc.version, { strict = true }))
+          end
+        )
+      end
+    end)
+
+    describe('strict=false', function()
+      local testcases = {
+        {
+          desc = 'version missing patch version',
+          version = '1.2',
+          want = { major = 1, minor = 2, patch = 0 },
+        },
+        {
+          desc = 'version missing minor and patch version',
+          version = '1',
+          want = { major = 1, minor = 0, patch = 0 },
+        },
+        {
+          desc = 'version missing patch version with prerelease',
+          version = '1.1-0',
+          want = { major = 1, minor = 1, patch = 0, prerelease = '0' },
+        },
+        {
+          desc = 'version missing minor and patch version with prerelease',
+          version = '1-1.0',
+          want = { major = 1, minor = 0, patch = 0, prerelease = '1.0' },
+        },
+      }
+      for _, tc in ipairs(testcases) do
+        it(
+          string.format('for %q: version = %q', tc.desc, tc.version),
+          function()
+            eq(tc.want, version.parse(tc.version, { strict = false }))
+          end
+        )
+      end
+    end)
+
+    describe('invalid semver', function()
+      local testcases = {
+        { desc = 'a word', version = 'foo' },
+        { desc = 'empty string', version = '' },
+        { desc = 'trailing period character', version = '0.0.0.' },
+        { desc = 'leading period character', version = '.0.0.0' },
+        { desc = 'negative major version', version = '-1.0.0' },
+        { desc = 'negative minor version', version = '0.-1.0' },
+        { desc = 'negative patch version', version = '0.0.-1' },
+        { desc = 'leading invalid string', version = 'foobar1.2.3' },
+        { desc = 'trailing invalid string', version = '1.2.3foobar' },
+        { desc = 'an invalid prerelease', version = '1.2.3-%?' },
+        { desc = 'an invalid build', version = '1.2.3+%?' },
+        { desc = 'build metadata before prerelease', version = '1.2.3+build.0-rc1' },
+      }
+      for _, tc in ipairs(testcases) do
+        it(string.format('(%s): %s', tc.desc, quote_empty(tc.version)), function()
+          eq(nil, version.parse(tc.version, { strict = true }))
+        end)
+      end
+    end)
+
+    describe('invalid shape', function()
+      local testcases = {
+        { desc = 'no parameters' },
+        { desc = 'nil', version = nil },
+        { desc = 'number', version = 0 },
+        { desc = 'float', version = 0.01 },
+        { desc = 'table', version = {} },
+      }
+      for _, tc in ipairs(testcases) do
+        it(string.format('(%s): %s', tc.desc, tostring(tc.version)), function()
+          local expected = string.format(type(tc.version) == 'string'
+            and 'invalid version: "%s"' or 'invalid version: %s', tostring(tc.version))
+          matches(expected, pcall_err(version.parse, tc.version, { strict = true }))
+        end)
+      end
+    end)
+  end)
+
+  it('lt()', function()
+    eq(true, version.lt('1', '2'))
+  end)
+
+  it('gt()', function()
+    eq(true, version.gt('2', '1'))
+  end)
+
+  it('eq()', function()
+    eq(true, version.eq('2', '2'))
+  end)
+end)