failing test for module not found error

The "not found" error should use the raw string directly from the config
source, but the existing method was adding the default registry if there
was no host indicated.

config/module/registry_test.go

@@ -2,6 +2,7 @@ package module
 
 import (
 	"os"
+	"strings"
 	"testing"
 
 	version "github.com/hashicorp/go-version"
@@ -93,6 +94,7 @@ func TestRegistryAuth(t *testing.T) {
 	}
 
 }
+
 func TestLookupModuleLocationRelative(t *testing.T) {
 	server := mockRegistry()
 	defer server.Close()
@@ -117,6 +119,7 @@ func TestLookupModuleLocationRelative(t *testing.T) {
 	}
 
 }
+
 func TestAccLookupModuleVersions(t *testing.T) {
 	if os.Getenv("TF_ACC") == "" {
 		t.Skip()
@@ -163,3 +166,29 @@ func TestAccLookupModuleVersions(t *testing.T) {
 		}
 	}
 }
+
+// the error should reference the config source exatly, not the discovered path.
+func TestLookupLookupModuleError(t *testing.T) {
+	server := mockRegistry()
+	defer server.Close()
+
+	regDisco := testDisco(server)
+	storage := testStorage(t, regDisco)
+
+	// this should not be found in teh registry
+	src := "bad/local/path"
+	mod, err := regsrc.ParseModuleSource(src)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	_, err = storage.lookupModuleLocation(mod, "0.2.0")
+	if err == nil {
+		t.Fatal("expected error")
+	}
+
+	// check for the exact quoted string to ensure we didn't prepend a hostname.
+	if !strings.Contains(err.Error(), `"bad/local/path"`) {
+		t.Fatal("error should not include the hostname. got:", err)
+	}
+}