1 files changed, 142 insertions, 0 deletions
diff --git a/tests/mason-core/functional/function_spec.lua b/tests/mason-core/functional/function_spec.lua
new file mode 100644
index 00000000..8c4b41ef
--- /dev/null
+++ b/tests/mason-core/functional/function_spec.lua
@@ -0,0 +1,142 @@
+local spy = require "luassert.spy"
+local match = require "luassert.match"
+local _ = require "mason-core.functional"
+
+describe("functional: function", function()
+    it("curries functions", function()
+        local function sum(...)
+            local res = 0
+            for i = 1, select("#", ...) do
+                res = res + select(i, ...)
+            end
+            return res
+        end
+        local arity0 = _.curryN(sum, 0)
+        local arity1 = _.curryN(sum, 1)
+        local arity2 = _.curryN(sum, 2)
+        local arity3 = _.curryN(sum, 3)
+
+        assert.equals(0, arity0(42))
+        assert.equals(42, arity1(42))
+        assert.equals(3, arity2(1)(2))
+        assert.equals(3, arity2(1, 2))
+        assert.equals(6, arity3(1)(2)(3))
+        assert.equals(6, arity3(1, 2, 3))
+
+        -- should discard superfluous args
+        assert.equals(0, arity1(0, 10, 20, 30))
+    end)
+
+    it("coalesces first non-nil value", function()
+        assert.equal("Hello World!", _.coalesce(nil, nil, "Hello World!", ""))
+    end)
+
+    it("should compose functions", function()
+        local function add(x)
+            return function(y)
+                return y + x
+            end
+        end
+        local function subtract(x)
+            return function(y)
+                return y - x
+            end
+        end
+        local function multiply(x)
+            return function(y)
+                return y * x
+            end
+        end
+
+        local big_maths = _.compose(add(1), subtract(3), multiply(5))
+
+        assert.equals(23, big_maths(5))
+    end)
+
+    it("should not allow composing no functions", function()
+        local e = assert.error(function()
+            _.compose()
+        end)
+        assert.equals("compose requires at least one function", e)
+    end)
+
+    it("should partially apply functions", function()
+        local funcy = spy.new()
+        local partially_funcy = _.partial(funcy, "a", "b", "c")
+        partially_funcy("d", "e", "f")
+        assert.spy(funcy).was_called_with("a", "b", "c", "d", "e", "f")
+    end)
+
+    it("should partially apply functions with nil arguments", function()
+        local funcy = spy.new()
+        local partially_funcy = _.partial(funcy, "a", nil, "c")
+        partially_funcy("d", nil, "f")
+        assert.spy(funcy).was_called_with("a", nil, "c", "d", nil, "f")
+    end)
+
+    it("memoizes functions with default cache mechanism", function()
+        local expensive_function = spy.new(function(s)
+            return s
+        end)
+        local memoized_fn = _.memoize(expensive_function)
+        assert.equal("key", memoized_fn "key")
+        assert.equal("key", memoized_fn "key")
+        assert.equal("new_key", memoized_fn "new_key")
+        assert.spy(expensive_function).was_called(2)
+    end)
+
+    it("memoizes function with custom cache mechanism", function()
+        local expensive_function = spy.new(function(arg1, arg2)
+            return arg1 .. arg2
+        end)
+        local memoized_fn = _.memoize(expensive_function, function(arg1, arg2)
+            return arg1 .. arg2
+        end)
+        assert.equal("key1key2", memoized_fn("key1", "key2"))
+        assert.equal("key1key2", memoized_fn("key1", "key2"))
+        assert.equal("key1key3", memoized_fn("key1", "key3"))
+        assert.spy(expensive_function).was_called(2)
+    end)
+
+    it("should evaluate functions lazily", function()
+        local impl = spy.new(function()
+            return {}, {}
+        end)
+        local lazy_fn = _.lazy(impl)
+        assert.spy(impl).was_called(0)
+        local a, b = lazy_fn()
+        assert.spy(impl).was_called(1)
+        assert.is_true(match.is_table()(a))
+        assert.is_true(match.is_table()(b))
+        local new_a, new_b = lazy_fn()
+        assert.spy(impl).was_called(1)
+        assert.is_true(match.is_ref(a)(new_a))
+        assert.is_true(match.is_ref(b)(new_b))
+    end)
+
+    it("should support nil return values in lazy functions", function()
+        local lazy_fn = _.lazy(function()
+            return nil, 2
+        end)
+        local a, b = lazy_fn()
+        assert.is_nil(a)
+        assert.equal(2, b)
+    end)
+
+    it("should provide identity value", function()
+        local obj = {}
+        assert.equals(2, _.identity(2))
+        assert.equals(obj, _.identity(obj))
+    end)
+
+    it("should always return bound value", function()
+        local obj = {}
+        assert.equals(2, _.always(2)())
+        assert.equals(obj, _.always(obj)())
+    end)
+
+    it("true is true and false is false", function()
+        assert.is_true(_.T())
+        assert.is_false(_.F())
+    end)
+end)