Fix install-unstable-test-master for packages (#612)

Author: lydell

lib/Install.js

@@ -169,28 +169,41 @@ function getDirectTestDependencies(
 
 const PKG = 'elm-explorations/test';
 const VERSION = '1.2.2';
+const VERSION_RANGE = '1.2.2 <= v < 2.0.0';
+
+function getExpectedVersion(
+  project /*: typeof Project.Project */
+) /*: string */ {
+  switch (project.elmJson.type) {
+    case 'application':
+      return VERSION;
+    case 'package':
+      return VERSION_RANGE;
+  }
+}
 
 async function installUnstableTestMaster(
   project /*: typeof Project.Project */
 ) /*: Promise<void> */ {
   const directTestDependencies = getDirectTestDependencies(project);
   const actualVersion = directTestDependencies[PKG];
-  if (actualVersion !== VERSION) {
+  const expectedVersion = getExpectedVersion(project);
+  if (actualVersion.replace(/\s/g, '') !== expectedVersion.replace(/\s/g, '')) {
     throw new Error(
       `
 Could not find ${JSON.stringify(PKG)}: ${JSON.stringify(
-        VERSION
+        expectedVersion
       )} in your elm.json file here:
 
 ${ElmJson.getPath(project.rootDir)}
 
 This command only works if you have ${PKG} as a (direct) test-dependency,
-and only if you use version ${VERSION}.
+and only if you use ${JSON.stringify(expectedVersion)}.
 
 ${
   actualVersion === undefined
     ? 'I could not find it at all.'
-    : `You seem to be using version ${actualVersion}.`
+    : `You seem to be using ${JSON.stringify(actualVersion)}.`
 }
     `.trim()
     );