fix: update tests and error messages

It turns out that the combination of testing tools we used before the previous
commit was buggy and did not run all the tests we thought should run! The update
revealed the issue. Since the suite needed updating, we did that and updated
some of the error messages.

index.js

@@ -166,17 +166,20 @@ exports.getVersion = Promise.method((filename) => {
  * @param {string} filename The name of the file from which to extract a
  * version.
  *
- * @return {VersionInfo} The version information or ``undefined`` if no version
- * can be found or if the version is not a valid semver version.
+ * @return {VersionInfo} The version information.
  *
  * @throws {InvalidVersionError} If the version is not a valid semver version.
  */
 exports.getValidVersion = function getValidVersion(filename) {
   return exports.getVersion(filename).then((current) => {
     const version = current && current.version;
+    if (!version) {
+      throw new InvalidVersionError(`Missing version number in ${filename}.`);
+    }
+
     if (!semver.valid(version)) {
       throw new InvalidVersionError(
-        `Missing or wrong semver number in ${filename}. Found: ${version}`);
+        `Invalid semver number in ${filename}. Found: ${version}`);
     }
 
     return current;

test/index.js

@@ -435,7 +435,7 @@ describe("Runner", () => {
     makeTest("rejects when there is an error", ["package.json", "amd.js"],
              runner => assert.isRejected(
                runner.verify(), Error,
-               "Version number is out of sync in amd.js."),
+               `Version number is out of sync in ${"amd.js".red}.`),
              ["amd.js"]);
   });
 
@@ -658,8 +658,8 @@ describe("running versync", () => {
 
     yield execVersync("-v -s invalid.js", true).catch((err) => {
       assert.equal(cleanOutput(err.stdout),
-                   "[ERROR] Missing or wrong semver number in " +
-                   "invalid.js. Found: version\n");
+                   "[ERROR] Invalid semver number in invalid.js. " +
+                   "Found: version\n");
     });
   }));
 });