ensure-add/avoid panic when adding current project as its own dependency

cmd/dep/ensure.go

@@ -500,6 +500,11 @@ func (cmd *ensureCommand) runAdd(ctx *dep.Ctx, args []string, p *dep.Project, sm
 			return err
 		}
 
+		// check if the the parsed path is the current root path
+		if strings.EqualFold(string(p.ImportRoot), string(pc.Ident.ProjectRoot)) {
+			return errors.New("cannot add current project to itself")
+		}
+
 		inManifest := p.Manifest.HasConstraintsOn(pc.Ident.ProjectRoot)
 		inImports := exrmap[pc.Ident.ProjectRoot]
 		if inManifest && inImports {

cmd/dep/testdata/harness_tests/ensure/add/errs/self-add/case1/final/Gopkg.toml

@@ -0,0 +1,3 @@
+[[constraint]]
+  name = "github.com/sdboyer/deptest"
+  version = "1.0.0"

cmd/dep/testdata/harness_tests/ensure/add/errs/self-add/case1/initial/Gopkg.toml

@@ -0,0 +1,3 @@
+[[constraint]]
+  name = "github.com/sdboyer/deptest"
+  version = "1.0.0"

cmd/dep/testdata/harness_tests/ensure/add/errs/self-add/case1/initial/main.go

@@ -0,0 +1,13 @@
+// Copyright 2016 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+import (
+	"github.com/sdboyer/deptest"
+)
+
+func main() {
+	_ := deptest.Map["yo yo!"]
+}

cmd/dep/testdata/harness_tests/ensure/add/errs/self-add/case1/testcase.json

@@ -0,0 +1,6 @@
+{
+  "commands": [
+    ["ensure", "-add", "github.com/golang/notexist"]
+  ],
+  "error-expected": "cannot add current project to itself"
+}

cmd/dep/testdata/harness_tests/ensure/add/errs/self-add/case2/initial/main.go

@@ -0,0 +1,7 @@
+// Copyright 2017 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+package main
+
+func main() {}

cmd/dep/testdata/harness_tests/ensure/add/errs/self-add/case2/testcase.json

@@ -0,0 +1,7 @@
+{
+  "commands": [
+    ["init", "-no-examples"],
+    ["ensure", "-add", "github.com/golang/notexist"]
+  ],
+  "error-expected": "cannot add current project to itself"
+}