feat(help): refactor npm help/help-search

Lots of dead code removed thanks to streamlining of logic.
`npm help` `npm <command>` and `npm help-search` are all now separated
concerns, handling their own use cases. `help` calls `help-search` as a
last resort, but `npm <command>` no longer tries to wind its way through
to `help-search` just to get the basic npm usage displayed.

The `did you mean` output has been expanded. It now always suggests top
level commands, scripts, and bins, and suggests them in the way they
should be called.

PR-URL: https://github.com/npm/cli/pull/2859
Credit: @wraithgar
Close: #2859
Reviewed-by: @ruyadorno

1 files changed, 23 insertions, 3 deletions

diff --git a/test/lib/run-script.js b/test/lib/run-script.js
index c598ea707..d2cac2f42 100644
--- a/test/lib/run-script.js
+++ b/test/lib/run-script.js
@@ -16,6 +16,11 @@ const npm = mockNpm({
   localPrefix: __dirname,
   flatOptions,
   config,
+  commands: {
+    help: {
+      description: 'test help description',
+    },
+  },
   output: (...msg) => output.push(msg),
 })
 
@@ -259,20 +264,35 @@ t.test('try to run missing script', t => {
   npm.localPrefix = t.testdir({
     'package.json': JSON.stringify({
       scripts: { hello: 'world' },
+      bin: { goodnight: 'moon' },
     }),
   })
   t.test('no suggestions', t => {
     runScript.exec(['notevenclose'], er => {
       t.match(er, {
-        message: 'missing script: notevenclose',
+        message: 'Unknown command: "notevenclose"',
       })
       t.end()
     })
   })
-  t.test('suggestions', t => {
+  t.test('script suggestions', t => {
     runScript.exec(['helo'], er => {
       t.match(er, {
-        message: 'missing script: helo\n\nDid you mean this?\n    hello',
+        message: 'Unknown command: "helo"',
+      })
+      t.match(er, {
+        message: 'npm run hello',
+      })
+      t.end()
+    })
+  })
+  t.test('bin suggestions', t => {
+    runScript.exec(['goodneght'], er => {
+      t.match(er, {
+        message: 'Unknown command: "goodneght"',
+      })
+      t.match(er, {
+        message: 'npm exec goodnight',
       })
       t.end()
     })