add tests to topics.Match, fix # matcher (#353)

Author: lhns

backends/topics/topics.go

@@ -7,17 +7,14 @@ func Match(savedTopic, givenTopic string) bool {
 	return givenTopic == savedTopic || match(strings.Split(savedTopic, "/"), strings.Split(givenTopic, "/"))
 }
 
-// TODO: I've always trusted this function does the right thing,
-// and it's kind of been proven by use and indirect testing of backends,
-// but it should really have tests of its own.
 func match(route []string, topic []string) bool {
 	switch {
 	case len(route) == 0:
 		return len(topic) == 0
 	case len(topic) == 0:
 		return route[0] == "#"
 	case route[0] == "#":
-		return true
+		return len(route) == 1 // '#' must be last in pattern
 	case route[0] == "+", route[0] == topic[0]:
 		return match(route[1:], topic[1:])
 	}

backends/topics/topics_test.go

@@ -0,0 +1,94 @@
+package topics
+
+import (
+	"fmt"
+	. "github.com/smartystreets/goconvey/convey"
+	"testing"
+)
+
+func TestTopicsMatch(t *testing.T) {
+	Convey("Match should match mqtt topics correctly", t, func() {
+		tests := []struct {
+			pattern  string
+			topic    string
+			expected bool
+		}{
+			// Exact matches
+			{"a/b/c", "a/b/c", true},
+			{"a/b", "a/b", true},
+			{"a", "a", true},
+
+			{"a/b", "a/x", false},
+			{"a/b", "x/b", false},
+
+			// Single-level wildcard +
+			{"a/+/c", "a/b/c", true},
+			{"a/+/c", "a/x/c", true},
+			{"+/+/+", "a/b/c", true},
+			{"+/b/+", "a/b/c", true},
+			{"a/b/+", "a/b/c", true},
+			{"+", "a", true},
+
+			{"a/+/c", "a/x/x", false},
+
+			// Wrong segment count with +
+			{"a/+/c", "a/c", false},
+			{"a/+/c", "a/b/c/d", false},
+			{"+/+", "a", false},
+			{"+/+", "a/b/c", false},
+
+			// Multi-level wildcard #
+			{"a/b/#", "a/b", true},
+			{"a/b/#", "a/b/c", true},
+			{"a/b/#", "a/b/c/d/e", true},
+			{"#", "a", true},
+			{"#", "a/b/c", true},
+			{"#", "/", true},
+			{"#", "//", true},
+
+			{"a/b/#", "a", false},
+			{"a/b/#", "a/x/c", false},
+
+			// # cannot match middle segments
+			{"a/#/c", "a/b/c", false},
+
+			// Pattern longer than topic
+			{"a/b/c/d", "a/b/c", false},
+			{"a/b/+", "a/b", false},
+
+			// Topic longer than pattern
+			{"a/b", "a/b/c", false},
+			{"a/b/c", "a/b/c/d", false},
+			{"a/b/+", "a/b/c/d", false},
+
+			// Empty topic and pattern
+			{"", "", true},
+			{"#", "", true},
+			{"+", "", true},
+
+			{"", "a", false},
+
+			// Trailing slashes
+			{"a/b/", "a/b/", true},
+
+			{"a/b", "a/b/", false},
+			{"a/b/", "a/b", false},
+
+			// Topic with empty segments
+			{"a//c", "a//c", true},
+			{"a/+/c", "a//c", true},
+		}
+
+		for i, test := range tests {
+			Convey(fmt.Sprintf("#%d: Match(%s, %s)", i, test.pattern, test.topic), func() {
+				result := Match(test.pattern, test.topic)
+
+				if result != test.expected {
+					fmt.Printf("\nFAILED test #%d: pattern=%q topic=%q → got=%v, expected=%v\n", i, test.topic, test.pattern, result, test.expected)
+				}
+
+				So(result, ShouldEqual, test.expected)
+			})
+		}
+	})
+}