chore: add case tests

tests/coerce/case_spec.lua

@@ -1,6 +1,36 @@
 local cc = require("coerce.case")
 
 describe("coerce.case", function()
+	describe("to_camel_case", function()
+		it("converts to camel case", function()
+			assert.are.same("ąbęÓcki", cc.to_camel_case("ąbę-ócki"))
+		end)
+	end)
+	describe("to_dot_case", function()
+		it("converts to dot case", function()
+			assert.are.same("ąbę.ócki", cc.to_dot_case("ąbę-ócki"))
+		end)
+	end)
+	describe("to_kebab_case", function()
+		it("converts to kebab case", function()
+			assert.are.same("ąbę-ócki", cc.to_kebab_case("ąbęÓcki"))
+		end)
+	end)
+	describe("to_pascal_case", function()
+		it("converts to pascal case", function()
+			assert.are.same("ĄbęÓcki", cc.to_pascal_case("ąbęÓcki"))
+		end)
+	end)
+	describe("to_snake_case", function()
+		it("converts to pascal case", function()
+			assert.are.same("ąbę_ócki", cc.to_snake_case("ąbęÓcki"))
+		end)
+	end)
+	describe("to_upper_case", function()
+		it("converts to upper case", function()
+			assert.are.same("ĄBĘ_ÓCKI", cc.to_upper_case("ąbęÓcki"))
+		end)
+	end)
 	describe("to_numerical_contraction", function()
 		it("converts a complex Unicode string its numerical contraction", function()
 			local char2nr = vim.fn.char2nr