From fdffeee7dc2a4869c85f0c298e3d12924846724b Mon Sep 17 00:00:00 2001
From: Stefan Majewsky <majewsky@gmx.net>
Date: Sat, 28 Mar 2020 14:18:07 +0100
Subject: add test coverage for ExpandRemoteURL, add ContractRemoteURL

---
 internal/rtree/remote.go      | 19 ++++++++++++
 internal/rtree/remote_test.go | 68 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 87 insertions(+)
 create mode 100644 internal/rtree/remote_test.go

diff --git a/internal/rtree/remote.go b/internal/rtree/remote.go
index 0c4e880..b2b3340 100644
--- a/internal/rtree/remote.go
+++ b/internal/rtree/remote.go
@@ -49,6 +49,25 @@ func ExpandRemoteURL(remoteURL string) string {
 	return best.Replacement + strings.TrimPrefix(remoteURL, best.Alias)
 }
 
+//ContractRemoteURL takes the canonical URL for a given remote and shortens it
+//as much as possible by substituting an alias from the system-wide and
+//user-global Git config. This function is pretty much the reverse of
+//ExpandRemoteURL().
+func ContractRemoteURL(remoteURL string) string {
+	var best *RemoteAlias
+	for _, current := range RemoteAliases {
+		if strings.HasPrefix(remoteURL, current.Replacement) {
+			if best == nil || len(best.Replacement) < len(current.Replacement) {
+				best = current
+			}
+		}
+	}
+	if best == nil {
+		return remoteURL
+	}
+	return best.Alias + strings.TrimPrefix(remoteURL, best.Replacement)
+}
+
 //This regex recognizes the scp-like syntax for git remotes
 //(i.e. "[user@]example.org:path/to/repo") as specified by the "GIT URLS"
 //section of man:git-clone(1).
diff --git a/internal/rtree/remote_test.go b/internal/rtree/remote_test.go
new file mode 100644
index 0000000..3841c5b
--- /dev/null
+++ b/internal/rtree/remote_test.go
@@ -0,0 +1,68 @@
+/*******************************************************************************
+*
+* Copyright 2020 Stefan Majewsky <majewsky@gmx.net>
+*
+* This program is free software: you can redistribute it and/or modify it under
+* the terms of the GNU General Public License as published by the Free Software
+* Foundation, either version 3 of the License, or (at your option) any later
+* version.
+*
+* This program is distributed in the hope that it will be useful, but WITHOUT ANY
+* WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
+* A PARTICULAR PURPOSE. See the GNU General Public License for more details.
+*
+* You should have received a copy of the GNU General Public License along with
+* this program. If not, see <http://www.gnu.org/licenses/>.
+*
+*******************************************************************************/
+
+package rtree
+
+import "testing"
+
+var remoteAliasesForExpansionTest = []*RemoteAlias{
+	{Alias: "gh:f:", Replacement: "https://github.com/foo/"},
+	{Alias: "gh:", Replacement: "https://github.com/"},
+	{Alias: "gh:b:", Replacement: "https://github.com/bar/"},
+	{Alias: "gl:", Replacement: "git://gitlab.com/"},
+	{Alias: "test:", Replacement: "test:test:"},
+}
+
+var testExpansions = map[string]string{
+	"gh:foo/bar":                 "https://github.com/foo/bar",
+	"gh:f:bar":                   "https://github.com/foo/bar",
+	"gh:b:foo":                   "https://github.com/bar/foo",
+	"gh:gh:foo/bar":              "https://github.com/gh:foo/bar", //do not expand multiple times
+	"test:foo":                   "test:test:foo",                 //do not expand recursively
+	"https://github.com/foo/bar": "https://github.com/foo/bar",    //no expansion at all
+}
+
+func TestExpandRemoteURL(t *testing.T) {
+	RemoteAliases = remoteAliasesForExpansionTest
+	for input, expected := range testExpansions {
+		actual := ExpandRemoteURL(input)
+		if actual != expected {
+			t.Errorf("expected %q to expand into %q, but got %q", input, expected, actual)
+		}
+	}
+}
+
+//Most of those are just reversed from `testExpansions`.
+var testContractions = map[string]string{
+	"https://github.com/foo/bar":      "gh:f:bar",
+	"https://github.com/bar/foo":      "gh:b:foo",
+	"https://github.com/qux/foobar":   "gh:qux/foobar",
+	"https://github.com/gh:foo/bar":   "gh:gh:foo/bar",
+	"test:test:foo":                   "test:foo",
+	"git://somewhereelse.com/foo/bar": "git://somewhereelse.com/foo/bar",
+}
+
+func TestContractRemoteURL(t *testing.T) {
+	RemoteAliases = remoteAliasesForExpansionTest
+	for input, expected := range testContractions {
+		actual := ContractRemoteURL(input)
+		if actual != expected {
+			t.Errorf("expected %q to contract into %q, but got %q", input, expected, actual)
+		}
+	}
+}
-- 
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