make docker-credential-wincred work like docker-credential-osxkeychain

* fetch credentials for server with matching hostname if scheme, path, or port are not provided
* if the credential request includes specific scheme, path, or port that does not match entry, don't return
* extract url helpers into a package

Signed-off-by: Emily Casey <ecasey@pivotal.io>
Signed-off-by: Danny Joyce <djoyce@pivotal.io>

registryurl/parse_test.go

@@ -0,0 +1,46 @@
+package registryurl
+
+import (
+	"errors"
+	"testing"
+)
+
+// TestHelperParseURL verifies that a // "scheme" is added to URLs,
+// and that invalid URLs produce an error.
+func TestHelperParseURL(t *testing.T) {
+	tests := []struct {
+		url         string
+		expectedURL string
+		err         error
+	}{
+		{url: "foobar.docker.io", expectedURL: "//foobar.docker.io"},
+		{url: "foobar.docker.io:2376", expectedURL: "//foobar.docker.io:2376"},
+		{url: "//foobar.docker.io:2376", expectedURL: "//foobar.docker.io:2376"},
+		{url: "http://foobar.docker.io:2376", expectedURL: "http://foobar.docker.io:2376"},
+		{url: "https://foobar.docker.io:2376", expectedURL: "https://foobar.docker.io:2376"},
+		{url: "https://foobar.docker.io:2376/some/path", expectedURL: "https://foobar.docker.io:2376/some/path"},
+		{url: "https://foobar.docker.io:2376/some/other/path?foo=bar", expectedURL: "https://foobar.docker.io:2376/some/other/path"},
+		{url: "/foobar.docker.io", err: errors.New("no hostname in URL")},
+		{url: "ftp://foobar.docker.io:2376", err: errors.New("unsupported scheme: ftp")},
+	}
+
+	for _, te := range tests {
+		u, err := Parse(te.url)
+
+		if te.err == nil && err != nil {
+			t.Errorf("Error: failed to parse URL %q: %s", te.url, err)
+			continue
+		}
+		if te.err != nil && err == nil {
+			t.Errorf("Error: expected error %q, got none when parsing URL %q", te.err, te.url)
+			continue
+		}
+		if te.err != nil && err.Error() != te.err.Error() {
+			t.Errorf("Error: expected error %q, got %q when parsing URL %q", te.err, err, te.url)
+			continue
+		}
+		if u != nil && u.String() != te.expectedURL {
+			t.Errorf("Error: expected URL: %q, but got %q for URL: %q", te.expectedURL, u.String(), te.url)
+		}
+	}
+}