ls: show relative paths from root, not absolute

Change the output in `npm ls` for symlink dependencies (including
workspaces) to show the relative path from the project root, rather than
the absolute path of the link target.

This makes the output much less noisy and more ergonomic when many
workspaces and link dependencies are in use, especially when paths are
long.

It is arguable that this output might be slightly misleading, since the
_actual_ workspace symlink from `${root}/node_modules/b` to
`${root}/packages/b` has a link value of `../packages/b`, not just
`packages/b`.  (Or on Windows, always the full absolute path, because
junctions.)  Thus, `npm ls b` will not show the same output as `ls -l
node_modules/b`.

However, `npm ls` shows the logical tree, not the physical tree, so
presenting the user with a path that they can use and interpret is more
important than presenting them with the strictly accurate details of
their filesystem.

lib/ls.js

@@ -1,4 +1,4 @@
-const { resolve } = require('path')
+const { resolve, relative } = require('path')
 const { EOL } = require('os')
 
 const archy = require('archy')
@@ -298,6 +298,9 @@ const getHumanOutputItem = (node, { args, color, global, long }) => {
     ? chalk.yellow.bgBlack
     : chalk.red.bgBlack
   const missingMsg = `UNMET ${isOptional(node) ? 'OPTIONAL ' : ''}DEPENDENCY`
+  const targetLocation = node.root
+    ? relative(node.root.realpath, node.realpath)
+    : node.targetLocation
   const label =
     (
       node[_missing]
@@ -321,7 +324,7 @@ const getHumanOutputItem = (node, { args, color, global, long }) => {
         : ''
     ) +
     (isGitNode(node) ? ` (${node.resolved})` : '') +
-    (node.isLink ? ` -> ${node.realpath}` : '') +
+    (node.isLink ? ` -> ${targetLocation}` : '') +
     (long ? `${EOL}${node.package.description || ''}` : '')
 
   return augmentItemWithIncludeMetadata(node, { label, nodes: [] })
@@ -453,6 +456,7 @@ const augmentNodesWithMetadata = ({
       path: node.path,
       isLink: node.isLink,
       realpath: node.realpath,
+      targetLocation: node.root ? relative(node.root.realpath, node.realpath) : node.targetLocation,
       [_type]: node[_type],
       [_invalid]: node[_invalid],
       [_missing]: node[_missing],

tap-snapshots/test/lib/ls.js.test.cjs

@@ -70,7 +70,7 @@ [email protected] {CWD}/tap-testdir-ls-ls---dev
 
 exports[`test/lib/ls.js TAP ls --link > should output tree containing linked deps 1`] = `
 [email protected] {CWD}/tap-testdir-ls-ls---link
-\`-- [email protected] -> {CWD}/tap-testdir-ls-ls---link/linked-dep
+\`-- [email protected] -> linked-dep
 
 `
 
@@ -480,59 +480,59 @@ exports[`test/lib/ls.js TAP ls json read problems > should print empty result 1`
 
 exports[`test/lib/ls.js TAP ls loading a tree containing workspaces > should filter by parent folder workspace config 1`] = `
 [email protected] {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces
-+-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/group/e
-\`-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/group/f
++-- [email protected] -> group/e
+\`-- [email protected] -> group/f
 
 `
 
 exports[`test/lib/ls.js TAP ls loading a tree containing workspaces > should filter single workspace 1`] = `
 [email protected] {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces
-+-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/a
-| \`-- [email protected] deduped -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/d
-\`-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/d
++-- [email protected] -> a
+| \`-- [email protected] deduped -> d
+\`-- [email protected] -> d
 
 `
 
 exports[`test/lib/ls.js TAP ls loading a tree containing workspaces > should filter using workspace config 1`] = `
 [email protected] {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces
-\`-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/a
+\`-- [email protected] -> a
   +-- [email protected]
-  \`-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/d
+  \`-- [email protected] -> d
     \`-- [email protected]
       \`-- [email protected]
 
 `
 
 exports[`test/lib/ls.js TAP ls loading a tree containing workspaces > should list --all workspaces properly 1`] = `
 [email protected] {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces
-+-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/a
++-- [email protected] -> a
 | +-- [email protected]
-| \`-- [email protected] deduped -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/d
-+-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/b
-+-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/d
+| \`-- [email protected] deduped -> d
++-- [email protected] -> b
++-- [email protected] -> d
 | \`-- [email protected]
 |   \`-- [email protected]
-+-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/group/e
-\`-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/group/f
++-- [email protected] -> group/e
+\`-- [email protected] -> group/f
 
 `
 
 exports[`test/lib/ls.js TAP ls loading a tree containing workspaces > should list workspaces properly with default configs 1`] = `
 [[email protected] {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces
-[0m+-- [[email protected][39m -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/a[0m
+[0m+-- [[email protected][39m -> a[0m
 | +-- [email protected]
-[0m| \`-- [email protected] [90mdeduped[39m -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/d[0m
-[0m+-- [[email protected][39m -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/b[0m
-[0m+-- [[email protected][39m -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/d[0m
+[0m| \`-- [email protected] [90mdeduped[39m -> d[0m
+[0m+-- [[email protected][39m -> b[0m
+[0m+-- [[email protected][39m -> d[0m
 | \`-- [email protected]
-[0m+-- [[email protected][39m -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/group/e[0m
-[0m\`-- [[email protected][39m -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/group/f[0m
+[0m+-- [[email protected][39m -> group/e[0m
+[0m\`-- [[email protected][39m -> group/f[0m
 
 `
 
 exports[`test/lib/ls.js TAP ls loading a tree containing workspaces > should print all tree and filter by dep within only the ws subtree 1`] = `
 [email protected] {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces
-\`-- [email protected] -> {CWD}/tap-testdir-ls-ls-loading-a-tree-containing-workspaces/d
+\`-- [email protected] -> d
   \`-- [email protected]
     \`-- [email protected]
 
@@ -567,8 +567,8 @@ [email protected] {CWD}/tap-testdir-ls-ls-no-args
 exports[`test/lib/ls.js TAP ls print deduped symlinks > should output tree containing linked deps 1`] = `
 [email protected] {CWD}/tap-testdir-ls-ls-print-deduped-symlinks
 +-- [email protected]
-| \`-- [email protected] deduped -> {CWD}/tap-testdir-ls-ls-print-deduped-symlinks/b
-\`-- [email protected] -> {CWD}/tap-testdir-ls-ls-print-deduped-symlinks/b
+| \`-- [email protected] deduped -> b
+\`-- [email protected] -> b
 
 `