fix: standardize x x@ and x@*

BREAKING CHANGE: `x` and `x@` now return the same spec as `x@*`

From #45:

Right now, `name@` and `name` are parsed with `{type:'tag', fetchSpec:
'latest'}`, but `name@*` is parsed as `{type: 'range'}`.  But since `''`
is a valid semver range, it should be parsed the same as `*`.

This also saves npm-package-arg from guessing the default tag, which
currently poses some semantic hazards.  npm (via npm-pick-manifest) will
prefer its default tag if given a range that includes it.  But
`name@latest` should always and only resolve to that specific version in
the dist-tags.  So npm-pick-manifest and pacote have to detect this and
do some extra work to figure out if `latest` was actually specified or
just guessed as a default.

lib/npa.js

@@ -39,11 +39,12 @@ function npa (arg, where) {
     spec = arg
   } else if (nameEndsAt > 0) {
     name = namePart
-    spec = arg.slice(nameEndsAt + 1)
+    spec = arg.slice(nameEndsAt + 1) || '*'
   } else {
     const valid = validatePackageName(arg)
     if (valid.validForOldPackages) {
       name = arg
+      spec = '*'
     } else {
       spec = arg
     }
@@ -113,7 +114,7 @@ function Result (opts) {
   this.name = undefined
   this.escapedName = undefined
   this.scope = undefined
-  this.rawSpec = opts.rawSpec == null ? '' : opts.rawSpec
+  this.rawSpec = opts.rawSpec
   this.saveSpec = opts.saveSpec
   this.fetchSpec = opts.fetchSpec
   if (opts.name) {
@@ -381,7 +382,7 @@ function fromAlias (res, where) {
 
 function fromRegistry (res) {
   res.registry = true
-  const spec = res.rawSpec === '' ? 'latest' : res.rawSpec.trim()
+  const spec = res.rawSpec.trim()
   // no save spec for registry components as we save based on the fetched
   // version, not on the argument so this can't compute that.
   res.saveSpec = null

test/basic.js

@@ -44,21 +44,21 @@ t.test('basic', function (t) {
       name: '@foo/bar',
       escapedName: '@foo%2fbar',
       scope: '@foo',
-      rawSpec: '',
+      rawSpec: '*',
       saveSpec: null,
-      fetchSpec: 'latest',
-      type: 'tag',
+      fetchSpec: '*',
+      type: 'range',
     },
 
     '@foo/bar@': {
       raw: '@foo/bar@',
       name: '@foo/bar',
       escapedName: '@foo%2fbar',
       scope: '@foo',
-      rawSpec: '',
+      rawSpec: '*',
       saveSpec: null,
-      fetchSpec: 'latest',
-      type: 'tag',
+      fetchSpec: '*',
+      type: 'range',
     },
 
     '@foo/bar@baz': {
@@ -113,11 +113,11 @@ t.test('basic', function (t) {
         registry: true,
         name: 'bar',
         escapedName: 'bar',
-        type: 'tag',
+        type: 'range',
         raw: 'bar',
-        rawSpec: '',
+        rawSpec: '*',
         saveSpec: null,
-        fetchSpec: 'latest',
+        fetchSpec: '*',
       },
     },
 
@@ -366,10 +366,10 @@ t.test('basic', function (t) {
       name: 'git',
       type: 'alias',
       subSpec: {
-        type: 'tag',
+        type: 'range',
         registry: true,
         name: 'not-git',
-        fetchSpec: 'latest',
+        fetchSpec: '*',
       },
       raw: 'git@npm:not-git',
     },
@@ -550,9 +550,9 @@ t.test('basic', function (t) {
     foo: {
       name: 'foo',
       escapedName: 'foo',
-      type: 'tag',
+      type: 'range',
       saveSpec: null,
-      fetchSpec: 'latest',
+      fetchSpec: '*',
       raw: 'foo',
     },
 

test/realize-package-specifier.js

@@ -8,7 +8,7 @@ test('realize-package-specifier', function (t) {
   result = npa('a.tar.gz', '/test/a/b')
   t.equal(result.type, 'file', 'local tarball')
   result = npa('d', '/test/a/b')
-  t.equal(result.type, 'tag', 'remote package')
+  t.equal(result.type, 'range', 'remote package')
   result = npa('file:./a.tar.gz', '/test/a/b')
   t.equal(result.type, 'file', 'local tarball')
   result = npa('file:./b', '/test/a/b')