test: improve error messaging and add more tests to enjoyBy feature

index.js

@@ -83,7 +83,13 @@ function pickManifest (packument, wanted, opts) {
   )
   if (!manifest) {
     err = new Error(
-      `No matching version found for ${packument.name}@${wanted}`
+      `No matching version found for ${packument.name}@${wanted}${
+        opts.enjoyBy
+          ? ` with an Enjoy By date of ${
+            new Date(opts.enjoyBy).toLocaleString()
+          }. Maybe try a different date?`
+          : ''
+      }`
     )
     err.code = 'ETARGET'
     err.name = packument.name

test/index.js

@@ -289,5 +289,15 @@ test('accepts opts.enjoyBy option to do date-based cutoffs', t => {
     enjoyBy: '2018-01-02'
   })
   t.equal(manifest.version, '2.0.0', 'filtered out 3.0.0 because of dates')
+  t.throws(() => {
+    pickManifest(metadata, '3.0.0', {
+      enjoyBy: '2018-01-02'
+    })
+  }, /Enjoy By date of/, 'trying to find by out-of-range version breaks')
+  t.throws(() => {
+    pickManifest(metadata, 'latest', {
+      enjoyBy: '2018-01-02'
+    })
+  }, /Enjoy By date of/, 'trying to find by tag breaks if date is out of range')
   t.done()
 })