1 files changed, 72 insertions, 0 deletions
diff --git a/tests/mason-core/EventEmitter_spec.lua b/tests/mason-core/EventEmitter_spec.lua
new file mode 100644
index 00000000..4b9e3a6e
--- /dev/null
+++ b/tests/mason-core/EventEmitter_spec.lua
@@ -0,0 +1,72 @@
+local spy = require "luassert.spy"
+local match = require "luassert.match"
+
+local a = require "mason-core.async"
+local EventEmitter = require "mason-core.EventEmitter"
+
+describe("EventEmitter", function()
+    it("should call registered event handlers", function()
+        local emitter = EventEmitter.init(setmetatable({}, { __index = EventEmitter }))
+        local my_event_handler = spy.new()
+        emitter:on(
+            "my:event",
+            my_event_handler --[[@as fun()]]
+        )
+
+        emitter:emit("my:event", { table = "value" })
+        emitter:emit("my:event", 1337, 42)
+
+        assert.spy(my_event_handler).was_called(2)
+        assert.spy(my_event_handler).was_called_with(match.same { table = "value" })
+        assert.spy(my_event_handler).was_called_with(1337, 42)
+    end)
+
+    it("should call registered event handlers only once", function()
+        local emitter = EventEmitter.init(setmetatable({}, { __index = EventEmitter }))
+        local my_event_handler = spy.new()
+        emitter:once(
+            "my:event",
+            my_event_handler --[[@as fun()]]
+        )
+
+        emitter:emit("my:event", { table = "value" })
+        emitter:emit("my:event", 1337, 42)
+
+        assert.spy(my_event_handler).was_called(1)
+        assert.spy(my_event_handler).was_called_with(match.same { table = "value" })
+    end)
+
+    it("should remove registered event handlers", function()
+        local emitter = EventEmitter.init(setmetatable({}, { __index = EventEmitter }))
+        local my_event_handler = spy.new()
+        emitter:on(
+            "my:event",
+            my_event_handler --[[@as fun()]]
+        )
+        emitter:once(
+            "my:event",
+            my_event_handler --[[@as fun()]]
+        )
+
+        emitter:off(
+            "my:event",
+            my_event_handler --[[@as fun()]]
+        )
+
+        emitter:emit("my:event", { table = "value" })
+        assert.spy(my_event_handler).was_called(0)
+    end)
+
+    it(
+        "should print errors in handlers",
+        async_test(function()
+            spy.on(vim.api, "nvim_err_writeln")
+            local emitter = EventEmitter.init(setmetatable({}, { __index = EventEmitter }))
+            emitter:on("event", mockx.throws "My error.")
+            emitter:emit "event"
+            a.scheduler()
+            assert.spy(vim.api.nvim_err_writeln).was_called(1)
+            assert.spy(vim.api.nvim_err_writeln).was_called_with "My error."
+        end)
+    )
+end)