explain-dep: handle shortening edge from root project

Fixes: #2134
Credit: @isaacs
Close: #2156
Reviewed-by: @ruyadorno

lib/utils/explain-dep.js

@@ -64,7 +64,7 @@ const explainDependents = ({ name, dependents }, depth, color) => {
     const maxLen = 50
     const showNames = []
     for (let i = max; i < dependents.length; i++) {
-      const { from: { name } } = dependents[i]
+      const { from: { name = 'the root project' } } = dependents[i]
       len += name.length
       if (len >= maxLen && i < dependents.length - 1) {
         showNames.push('...')

tap-snapshots/test-lib-utils-explain-dep.js-TAP.test.js

@@ -10,15 +10,15 @@ manydep@1.0.0
   manydep@"1.0.0" from prod-dep@1.2.3
   node_modules/prod-dep
     prod-dep@"1.x" from the root project
-  6 more (optdep, extra-neos, deep-dev, peer, ...)
+  7 more (optdep, extra-neos, deep-dev, peer, the root project, ...)
 `
 
 exports[`test/lib/utils/explain-dep.js TAP > ellipses test two 1`] = `
 manydep@1.0.0
   manydep@"1.0.0" from prod-dep@1.2.3
   node_modules/prod-dep
     prod-dep@"1.x" from the root project
-  5 more (optdep, extra-neos, deep-dev, peer, a package with a pretty long name)
+  6 more (optdep, extra-neos, deep-dev, peer, the root project, a package with a pretty long name)
 `
 
 exports[`test/lib/utils/explain-dep.js TAP deepDev > explain color deep 1`] = `
@@ -90,6 +90,7 @@ exports[`test/lib/utils/explain-dep.js TAP manyDeps > explain color deep 1`] = `
   peer manydep@">1.0.0-beta <1.0.1" from peer@1.0.0 peer
   node_modules/peer
     peer peer@"1.0.0" from the root project
+  manydep@">1.0.0-beta <1.0.1" from the root project
   manydep@"1" from a package with a pretty long name@1.2.3
   manydep@"1" from another package with a pretty long name@1.2.3
   manydep@"1" from yet another a package with a pretty long name@1.2.3
@@ -100,7 +101,7 @@ manydep@1.0.0
   manydep@"1.0.0" from prod-dep@1.2.3
   node_modules/prod-dep
     prod-dep@"1.x" from the root project
-  7 more (optdep, extra-neos, deep-dev, peer, ...)
+  8 more (optdep, extra-neos, deep-dev, peer, the root project, ...)
 `
 
 exports[`test/lib/utils/explain-dep.js TAP manyDeps > print color 1`] = `

test/lib/utils/explain-dep.js

@@ -2,7 +2,7 @@ const t = require('tap')
 const requireInject = require('require-inject')
 const npm = {}
 const { explainNode, printNode } = requireInject('../../../lib/utils/explain-dep.js', {
-  '../../../lib/npm.js': npm
+  '../../../lib/npm.js': npm,
 })
 
 const cases = {
@@ -16,10 +16,10 @@ const cases = {
         name: 'prod-dep',
         spec: '1.x',
         from: {
-          location: '/path/to/project'
-        }
-      }
-    ]
+          location: '/path/to/project',
+        },
+      },
+    ],
   },
 
   deepDev: {
@@ -51,16 +51,16 @@ const cases = {
                     name: 'topdev',
                     spec: '4.x',
                     from: {
-                      location: '/path/to/project'
-                    }
-                  }
-                ]
-              }
-            }
-          ]
-        }
-      }
-    ]
+                      location: '/path/to/project',
+                    },
+                  },
+                ],
+              },
+            },
+          ],
+        },
+      },
+    ],
   },
 
   optional: {
@@ -74,10 +74,10 @@ const cases = {
         name: 'optdep',
         spec: '1.0.0',
         from: {
-          location: '/path/to/project'
-        }
-      }
-    ]
+          location: '/path/to/project',
+        },
+      },
+    ],
   },
 
   peer: {
@@ -91,19 +91,19 @@ const cases = {
         name: 'peer',
         spec: '1.0.0',
         from: {
-          location: '/path/to/project'
-        }
-      }
-    ]
+          location: '/path/to/project',
+        },
+      },
+    ],
   },
 
   extraneous: {
     name: 'extra-neos',
     version: '1337.420.69-lol',
     location: 'node_modules/extra-neos',
     dependents: [],
-    extraneous: true
-  }
+    extraneous: true,
+  },
 }
 
 cases.manyDeps = {
@@ -114,31 +114,39 @@ cases.manyDeps = {
       type: 'prod',
       name: 'manydep',
       spec: '1.0.0',
-      from: cases.prodDep
+      from: cases.prodDep,
     },
     {
       type: 'optional',
       name: 'manydep',
       spec: '1.x',
-      from: cases.optional
+      from: cases.optional,
     },
     {
       type: 'prod',
       name: 'manydep',
       spec: '1.0.x',
-      from: cases.extraneous
+      from: cases.extraneous,
     },
     {
       type: 'dev',
       name: 'manydep',
       spec: '*',
-      from: cases.deepDev
+      from: cases.deepDev,
     },
     {
       type: 'peer',
       name: 'manydep',
       spec: '>1.0.0-beta <1.0.1',
-      from: cases.peer
+      from: cases.peer,
+    },
+    {
+      type: 'prod',
+      name: 'manydep',
+      spec:'>1.0.0-beta <1.0.1',
+      from: {
+        location: '/path/to/project',
+      },
     },
     {
       type: 'prod',
@@ -148,9 +156,9 @@ cases.manyDeps = {
         name: 'a package with a pretty long name',
         version: '1.2.3',
         dependents: {
-          location: '/path/to/project'
-        }
-      }
+          location: '/path/to/project',
+        },
+      },
     },
     {
       type: 'prod',
@@ -160,9 +168,9 @@ cases.manyDeps = {
         name: 'another package with a pretty long name',
         version: '1.2.3',
         dependents: {
-          location: '/path/to/project'
-        }
-      }
+          location: '/path/to/project',
+        },
+      },
     },
     {
       type: 'prod',
@@ -172,14 +180,13 @@ cases.manyDeps = {
         name: 'yet another a package with a pretty long name',
         version: '1.2.3',
         dependents: {
-          location: '/path/to/project'
-        }
-      }
+          location: '/path/to/project',
+        },
+      },
     },
-  ]
+  ],
 }
 
-
 for (const [name, expl] of Object.entries(cases)) {
   t.test(name, t => {
     npm.color = true