Add test units for the isSimilar function (#285) (#311)

test/Utility/isSimilar.spec.lua

@@ -0,0 +1,35 @@
+local Package = game:GetService("ReplicatedStorage").Fusion
+local isSimilar = require(Package.Utility.isSimilar)
+
+return function()
+    it("should return similar for identical values", function()
+        local value = 123
+
+        expect(isSimilar(value, value)).to.equal(true)
+    end)
+
+    it("should return non-similar for different values", function()
+        local value1 = 123
+        local value2 = 321
+
+        expect(isSimilar(value1, value2)).to.equal(false)
+    end)
+
+    it("should return similar for any NaN values", function()
+        local nan1 = 0 / 0
+        local nan2 = math.huge / math.huge
+
+        expect(isSimilar(nan1, nan1)).to.equal(true)
+        expect(isSimilar(nan1, nan2)).to.equal(true)
+    end)
+
+    it("should return non-similar for any tables", function()
+        local initialTable = { foo = 123, bar = "hello" }
+        local similarTable = { foo = 123, bar = "hello" }
+        local differentTable = { foo = 321, bar = "world" }
+
+        expect(isSimilar(initialTable, initialTable)).to.equal(false)
+        expect(isSimilar(initialTable, similarTable)).to.equal(false)
+        expect(isSimilar(initialTable, differentTable)).to.equal(false)
+    end)
+end