cmd/gio: generate appID if not specified

Use the Go import path to create an appID based on the domain name
plus the last directory location in the import path.

Signed-off-by: Greg Pomerantz <gmp.gio@wow.st>

cmd/gio/gio_test.go

@@ -0,0 +1,32 @@
+package main
+
+import (
+	"testing"
+)
+
+type expval struct {
+	in, out string
+}
+
+func TestAppID(t *testing.T) {
+	tests := []expval{
+		{"example", "localhost.example"},
+		{"example.com", "com.example"},
+		{"www.example.com", "com.example.www"},
+		{"examplecom/app", "examplecom.app"},
+		{"example.com/app", "com.example.app"},
+		{"www.example.com/app", "com.example.www.app"},
+		{"www.en.example.com/app", "com.example.en.www.app"},
+		{"example.com/dir/app", "com.example.app"},
+		{"example.com/dir.ext/app", "com.example.app"},
+		{"example.com/dir/app.ext", "com.example.app.ext"},
+		{"example-com.net/dir/app", "net.example_com.app"},
+	}
+
+	for i, test := range tests {
+		got := appIDFromPackage(test.in)
+		if exp := test.out; got != exp {
+			t.Errorf("(%d): expected '%s', got '%s'", i, exp, got)
+		}
+	}
+}