chore(tests): include basic stringification tests

tests/tostring.luau

@@ -9,7 +9,54 @@ local Semver = require("../lib")
 
 return function()
 	test.suite("Stringification tests", function()
-		test.case("A parsed version when stringified should not change", function()
+		test.case("A version constructed with new() when stringified should match expected string", function()
+			local versionMap: { [string]: Semver.Version } = {
+				["1.2.3"] = { major = 1, minor = 2, patch = 3, prerelease = Option.None, buildMetadata = Option.None },
+				["1.0.0-alpha"] = {
+					major = 1,
+					minor = 0,
+					patch = 0,
+					prerelease = Option.Some({ type = "alpha" :: Semver.PreleaseType, ordinal = Option.None }),
+					buildMetadata = Option.None,
+				},
+				["2.3.4-beta.1"] = {
+					major = 2,
+					minor = 3,
+					patch = 4,
+					prerelease = Option.Some({
+						type = "beta" :: Semver.PreleaseType,
+						ordinal = Option.Some(1),
+					}),
+					buildMetadata = Option.None,
+				},
+				["3.0.0-rc.1+build.123"] = {
+					major = 3,
+					minor = 0,
+					patch = 0,
+					prerelease = Option.Some({
+						type = "rc" :: Semver.PreleaseType,
+						ordinal = Option.Some(1),
+					}),
+					buildMetadata = Option.Some("build.123"),
+				},
+				["4.5.6+sha.xyz"] = {
+					major = 4,
+					minor = 5,
+					patch = 6,
+					prerelease = Option.None,
+					buildMetadata = Option.Some("sha.xyz"),
+				},
+			}
+
+			for expectedString, version in versionMap do
+				local constructed = Semver.new(version :: Semver.Version)
+				local stringified = tostring(constructed)
+
+				check.equal(stringified, expectedString)
+			end
+		end)
+
+		test.case("A parsed version when stringified should not change in roundtrip", function()
 			local versions = {
 				"1.2.3",
 				"1.0.0-alpha",