Fix var name generation to avoid conflict (#145)

When the type and the package name is the same for an anonymous
parameter (ex: time.Time), and there are more than 1 such parameters,
the generated name for both was the same. And the generated code would
not be valid.

Fix the bug by ensuring the parameter name does not conflict with
package imports first before checking against other parameter names.

internal/registry/var.go

@@ -38,7 +38,25 @@ func (v Var) packageQualifier(pkg *types.Package) string {
 	return v.imports[path].Qualifier()
 }
 
-// generateVarName generates a name for the variable using the type
+func varName(vr *types.Var, suffix string) string {
+	name := vr.Name()
+	if name != "" && name != "_" {
+		return name + suffix
+	}
+
+	name = varNameForType(vr.Type()) + suffix
+
+	switch name {
+	case "mock", "callInfo", "break", "default", "func", "interface", "select", "case", "defer", "go", "map", "struct",
+		"chan", "else", "goto", "package", "switch", "const", "fallthrough", "if", "range", "type", "continue", "for",
+		"import", "return", "var":
+		name += "MoqParam"
+	}
+
+	return name
+}
+
+// varNameForType generates a name for the variable using the type
 // information.
 //
 // Examples:
@@ -49,12 +67,12 @@ func (v Var) packageQualifier(pkg *types.Package) string {
 // - map[string]int -> stringToInt
 // - error -> err
 // - a.MyType -> myType
-func generateVarName(t types.Type) string {
+func varNameForType(t types.Type) string {
 	nestedType := func(t types.Type) string {
 		if t, ok := t.(*types.Basic); ok {
 			return deCapitalise(t.String())
 		}
-		return generateVarName(t)
+		return varNameForType(t)
 	}
 
 	switch t := t.(type) {
@@ -83,7 +101,7 @@ func generateVarName(t types.Type) string {
 		return "val"
 
 	case *types.Pointer:
-		return generateVarName(t.Elem())
+		return varNameForType(t.Elem())
 
 	case *types.Signature:
 		return "fn"