1 files changed, 63 insertions, 0 deletions
diff --git a/tests/mason-core/optional_spec.lua b/tests/mason-core/optional_spec.lua
new file mode 100644
index 00000000..e0068b10
--- /dev/null
+++ b/tests/mason-core/optional_spec.lua
@@ -0,0 +1,63 @@
+local Optional = require "mason-core.optional"
+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)