more command tests, added require_command

spec/commands_spec.lua

@@ -10,4 +10,53 @@ describe("tests related to commands", function()
       local args = parser:parse{"temp.txt", "remove"}
       assert.same({file = "temp.txt", remove = true}, args)
    end)
+
+   it("switches context properly", function()
+      local parser = argparse.parser "name"
+      local install = parser:command "install"
+      install:flag "-q" "--quiet"
+
+      local args = parser:parse{"install", "-q"}
+      assert.same({install = true, quiet = true}, args)
+      assert.has_error(function() parser:parse{"-q", "install"} end, "unknown option -q")
+   end)
+
+   it("allows to continue passing old options", function()
+      local parser = argparse.parser "name"
+      parser:flag "-v" "--verbose" {
+         count = "*"
+      }
+      parser:command "install"
+
+      local args = parser:parse{"-vv", "install", "--verbose"}
+      assert.same({install = true, verbose = 3}, args)
+   end)
+
+   it("handles nested commands", function()
+      local parser = argparse.parser "name"
+      local foo = parser:command "foo"
+      local bar = foo:command "bar"
+      local baz = foo:command "baz"
+
+      local args = parser:parse{"foo", "bar"}
+      assert.same({foo = true, bar = true}, args)
+   end)
+
+   it("handles no commands depending on parser.require_command", function()
+      local parser = argparse.parser "name"
+      parser:command "install"
+
+      local args = parser:parse{}
+      assert.same({}, args)
+
+      parser.require_command = true
+      assert.has_error(function() parser:parse{} end, "command is required")
+   end)
+
+   it("Detects wrong commands", function()
+      local parser = argparse.parser "name"
+      local install = parser:command "install"
+
+      assert.has_error(function() parser:parse{"isntall"} end, "unknown command isntall")
+   end)
 end)

src/argparse.lua

@@ -39,7 +39,8 @@ local Parser = class {
    arguments = {},
    options = {},
    commands = {},
-   fields = {"name", "description", "target"}
+   require_command = false,
+   fields = {"name", "description", "target", "require_command"}
 }:include(Declarative)
 
 local Command = Parser:extends {
@@ -448,6 +449,10 @@ function Parser:parse(args)
       close(cur_arg)
    end
 
+   if parser.require_command and #commands > 0 then
+      parser:error("command is required")
+   end
+
    format()
 
    return result