Fix Clue Mock Gen package name conflict (#259)

- Fix a bug where an alias is not used for the mocked package if it
  conflicts with one of the other intial imports (this was discovered
  with a package named `testing`, but it looks like it could also come
  up if it was named `mock` which would conflict with
  `goa.design/clue/mock`.
- Bump version so it will be correct for a new release.

mock/cmd/cmg/pkg/generate/_tests/conflicts/conflicts.go

@@ -0,0 +1,7 @@
+package testing
+
+type (
+	Conflicts interface {
+		Simple(c *Conflicts) *Conflicts
+	}
+)

mock/cmd/cmg/pkg/generate/mocks.go

@@ -42,22 +42,20 @@ var (
 
 func NewMocks(prefix string, p parse.Package, interfaces []parse.Interface, toolVersionFunc ToolVersionFunc) Mocks {
 	var (
-		m = &mocks{
-			pkgName:         prefix + p.Name(),
-			pkgPath:         p.PkgPath(),
-			pkgImport:       newImport(p.PkgPath(), p.Name()),
-			toolVersionFunc: toolVersionFunc,
-		}
 		stdImports = importMap{"testing": newImport("testing")}
 		extImports = importMap{"mock": newImport("goa.design/clue/mock")}
 		intImports = make(importMap)
 		modPath    = p.ModPath()
-		typeNames  = make(typeMap)
-		typeZeros  = make(typeMap)
+		m          = &mocks{
+			pkgName:         prefix + p.Name(),
+			pkgPath:         p.PkgPath(),
+			pkgImport:       addImport(newImport(p.PkgPath(), p.Name()), stdImports, extImports, intImports, modPath),
+			toolVersionFunc: toolVersionFunc,
+		}
+		typeNames = make(typeMap)
+		typeZeros = make(typeMap)
 	)
 
-	addImport(m.pkgImport, stdImports, extImports, intImports, modPath)
-
 	for _, i := range interfaces {
 		m.interfaces = append(m.interfaces, newInterface(i, typeNames, typeZeros, stdImports, extImports, intImports, modPath))
 	}

mock/cmd/cmg/pkg/generate/mocks.go.tmpl

@@ -36,8 +36,8 @@ type (
 {{ end }}
 func {{ .Constructor }}{{ .TypeParameters }}(t *testing.T) *{{ .Name }}{{ .TypeParameterVars }} {
 	var (
-		{{ .Var | printf ($import.PkgName | .ConstructorFmt) }} = &{{ .Name }}{{ .TypeParameterVars }}{mock.New(), t}
-		_ {{ $import.PkgName }}.{{ .Name }}{{ .TypeParameterVars }} = m
+		{{ .Var | printf ($import.AliasOrPkgName | .ConstructorFmt) }} = &{{ .Name }}{{ .TypeParameterVars }}{mock.New(), t}
+		_ {{ $import.AliasOrPkgName }}.{{ .Name }}{{ .TypeParameterVars }} = m
 	)
 	return {{ .Var }}
 }

mock/cmd/cmg/pkg/generate/mocks_test.go

@@ -22,6 +22,11 @@ func TestMocks_Render(t *testing.T) {
 			Pattern:       "./extensive",
 			ExpectedFiles: []string{"extensive.go"},
 		},
+		{
+			Name:          "conflicts",
+			Pattern:       "./conflicts",
+			ExpectedFiles: []string{"conflicts.go"},
+		},
 	}
 
 	for _, tc := range cases {

mock/cmd/cmg/pkg/version.go

@@ -8,7 +8,7 @@ const (
 	// Major version number
 	Major = 0
 	// Minor version number
-	Minor = 17
+	Minor = 18
 	// Build number
 	Build = 1
 	// Suffix - set to empty string in release tag commits.