Add util

util/grpc/grpc.go

@@ -0,0 +1,40 @@
+package grpc
+
+import (
+	"fmt"
+	"strings"
+)
+
+// ServiceMethod converts a gRPC method to a Go method
+// Input:
+// Foo.Bar, /Foo/Bar, /package.Foo/Bar, /a.package.Foo/Bar
+// Output:
+// [Foo, Bar]
+func ServiceMethod(m string) (string, string, error) {
+	if len(m) == 0 {
+		return "", "", fmt.Errorf("malformed method name: %q", m)
+	}
+
+	// grpc method
+	if m[0] == '/' {
+		// [ , Foo, Bar]
+		// [ , package.Foo, Bar]
+		// [ , a.package.Foo, Bar]
+		parts := strings.Split(m, "/")
+		if len(parts) != 3 || len(parts[1]) == 0 || len(parts[2]) == 0 {
+			return "", "", fmt.Errorf("malformed method name: %q", m)
+		}
+		service := strings.Split(parts[1], ".")
+		return service[len(service)-1], parts[2], nil
+	}
+
+	// non grpc method
+	parts := strings.Split(m, ".")
+
+	// expect [Foo, Bar]
+	if len(parts) != 2 {
+		return "", "", fmt.Errorf("malformed method name: %q", m)
+	}
+
+	return parts[0], parts[1], nil
+}

util/grpc/grpc_test.go

@@ -0,0 +1,46 @@
+package grpc
+
+import (
+	"testing"
+)
+
+func TestServiceMethod(t *testing.T) {
+	type testCase struct {
+		input   string
+		service string
+		method  string
+		err     bool
+	}
+
+	methods := []testCase{
+		{"Foo.Bar", "Foo", "Bar", false},
+		{"/Foo/Bar", "Foo", "Bar", false},
+		{"/package.Foo/Bar", "Foo", "Bar", false},
+		{"/a.package.Foo/Bar", "Foo", "Bar", false},
+		{"a.package.Foo/Bar", "", "", true},
+		{"/Foo/Bar/Baz", "", "", true},
+		{"Foo.Bar.Baz", "", "", true},
+	}
+	for _, test := range methods {
+		service, method, err := ServiceMethod(test.input)
+		if err != nil && test.err == true {
+			continue
+		}
+		// unexpected error
+		if err != nil && test.err == false {
+			t.Fatalf("unexpected err %v for %+v", err, test)
+		}
+		// expecter error
+		if test.err == true && err == nil {
+			t.Fatalf("expected error for %+v: got service: %s method: %s", test, service, method)
+		}
+
+		if service != test.service {
+			t.Fatalf("wrong service for %+v: got service: %s method: %s", test, service, method)
+		}
+
+		if method != test.method {
+			t.Fatalf("wrong method for %+v: got service: %s method: %s", test, service, method)
+		}
+	}
+}