Move git and url checks into pkg

This moves the IsGIT and IsURL functions out of the generic `utils`
package and into their own `urlutil` pkg.

Signed-off-by: Michael Crosby <crosbymichael@gmail.com>

urlutil/git.go

@@ -0,0 +1,30 @@
+package urlutil
+
+import "strings"
+
+var (
+	validPrefixes = []string{
+		"git://",
+		"github.com/",
+		"git@",
+	}
+)
+
+// IsGitURL returns true if the provided str is a git repository URL.
+func IsGitURL(str string) bool {
+	if IsURL(str) && strings.HasSuffix(str, ".git") {
+		return true
+	}
+	for _, prefix := range validPrefixes {
+		if strings.HasPrefix(str, prefix) {
+			return true
+		}
+	}
+	return false
+}
+
+// IsGitTransport returns true if the provided str is a git transport by inspecting
+// the prefix of the string for known protocols used in git.
+func IsGitTransport(str string) bool {
+	return IsURL(str) || strings.HasPrefix(str, "git://") || strings.HasPrefix(str, "git@")
+}

urlutil/git_test.go

@@ -0,0 +1,43 @@
+package urlutil
+
+import "testing"
+
+var (
+	gitUrls = []string{
+		"git://github.com/docker/docker",
+		"git@github.com:docker/docker.git",
+		"git@bitbucket.org:atlassianlabs/atlassian-docker.git",
+		"https://github.com/docker/docker.git",
+		"http://github.com/docker/docker.git",
+	}
+	incompleteGitUrls = []string{
+		"github.com/docker/docker",
+	}
+)
+
+func TestValidGitTransport(t *testing.T) {
+	for _, url := range gitUrls {
+		if IsGitTransport(url) == false {
+			t.Fatalf("%q should be detected as valid Git prefix", url)
+		}
+	}
+
+	for _, url := range incompleteGitUrls {
+		if IsGitTransport(url) == true {
+			t.Fatalf("%q should not be detected as valid Git prefix", url)
+		}
+	}
+}
+
+func TestIsGIT(t *testing.T) {
+	for _, url := range gitUrls {
+		if IsGitURL(url) == false {
+			t.Fatalf("%q should be detected as valid Git url", url)
+		}
+	}
+	for _, url := range incompleteGitUrls {
+		if IsGitURL(url) == false {
+			t.Fatalf("%q should be detected as valid Git url", url)
+		}
+	}
+}

urlutil/url.go

@@ -0,0 +1,19 @@
+package urlutil
+
+import "strings"
+
+var validUrlPrefixes = []string{
+	"http://",
+	"https://",
+}
+
+// IsURL returns true if the provided str is a valid URL by doing
+// a simple change for the transport of the url.
+func IsURL(str string) bool {
+	for _, prefix := range validUrlPrefixes {
+		if strings.HasPrefix(str, prefix) {
+			return true
+		}
+	}
+	return false
+}