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local Optional = require "mason-core.optional"
local Result = require "mason-core.result"
local spy = require "luassert.spy"
describe("Optional.of_nilable", function()
it("should create empty optionals", function()
local empty = Optional.empty()
assert.is_false(empty:is_present())
end)
it("should create non-empty optionals", function()
local empty = Optional.of_nilable "value"
assert.is_true(empty:is_present())
end)
it("should use memoized empty value", function()
assert.is_true(Optional.empty() == Optional.empty())
end)
end)
describe("Optional.get()", function()
it("should map non-empty values", function()
local str = Optional.of_nilable("world!")
:map(function(val)
return "Hello " .. val
end)
:get()
assert.equals("Hello world!", str)
end)
it("should raise error when getting empty value", function()
local err = assert.has_error(function()
Optional.empty():get()
end)
assert.equals("No value present.", err)
end)
end)
describe("Optional.or_else()", function()
it("should use .or_else() value if empty", function()
local value = Optional.empty():or_else "Hello!"
assert.equals("Hello!", value)
end)
it("should not use .or_else() value if not empty", function()
local value = Optional.of_nilable("Good bye!"):or_else "Hello!"
assert.equals("Good bye!", value)
end)
end)
describe("Optional.if_present()", function()
it("should not call .if_present() if value is empty", function()
local present = spy.new()
Optional.empty():if_present(present)
assert.spy(present).was_not_called()
end)
it("should call .if_present() if value is not empty", function()
local present = spy.new()
Optional.of_nilable("value"):if_present(present)
assert.spy(present).was_called(1)
assert.spy(present).was_called_with "value"
end)
end)
describe("Optional.if_not_present()", function()
it("should not call .if_not_present() if value is not empty", function()
local present = spy.new()
Optional.of_nilable("value"):if_not_present(present)
assert.spy(present).was_not_called()
end)
it("should call .if_not_present() if value is empty", function()
local present = spy.new()
Optional.empty():if_not_present(present)
assert.spy(present).was_called(1)
end)
end)
describe("Optional.ok_or()", function()
it("should return success variant if non-empty", function()
local result = Optional.of_nilable("Hello world!"):ok_or()
assert.is_true(getmetatable(result) == Result)
assert.equals("Hello world!", result:get_or_nil())
end)
it("should return failure variant if empty", function()
local result = Optional.empty():ok_or(function()
return "I'm empty."
end)
assert.is_true(getmetatable(result) == Result)
assert.equals("I'm empty.", result:err_or_nil())
end)
end)
describe("Optional.or_()", function()
it("should run supplier if value is not present", function()
local spy = spy.new(function()
return Optional.of "Hello world!"
end)
assert.same(Optional.of "Hello world!", Optional.empty():or_(spy))
assert.spy(spy).was_called(1)
assert.same(Optional.empty(), Optional.empty():or_(Optional.empty))
end)
it("should not run supplier if value is present", function()
local spy = spy.new(function()
return Optional.of "Hello world!"
end)
assert.same(Optional.of "Hello world!", Optional.of("Hello world!"):or_(spy))
assert.spy(spy).was_called(0)
end)
end)
describe("Optional.and_then()", function()
it("should run supplier if value is present", function()
local spy = spy.new(function(value)
return Optional.of(("%s world!"):format(value))
end)
assert.same(Optional.of "Hello world!", Optional.of("Hello"):and_then(spy))
assert.spy(spy).was_called(1)
assert.same(
Optional.empty(),
Optional.empty():and_then(function()
return Optional.of "Nothing."
end)
)
end)
it("should not run supplier if value is not present", function()
local spy = spy.new(function()
return Optional.of "Hello world!"
end)
assert.same(Optional.empty(), Optional.empty():and_then(spy))
assert.spy(spy).was_called(0)
end)
end)
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