diff --git a/adb_utils_test.cpp b/adb_utils_test.cpp
index f1ebaa1..aabc5d7 100644
--- a/adb_utils_test.cpp
+++ b/adb_utils_test.cpp
@@ -149,3 +149,24 @@
   ASSERT_EQ(0, adb_close(fd));
 }
 #endif
+
+TEST(adb_utils, test_forward_targets_are_valid) {
+    std::string error;
+
+    // Source port can be >= 0.
+    EXPECT_FALSE(forward_targets_are_valid("tcp:-1", "tcp:9000", &error));
+    EXPECT_TRUE(forward_targets_are_valid("tcp:0", "tcp:9000", &error));
+    EXPECT_TRUE(forward_targets_are_valid("tcp:8000", "tcp:9000", &error));
+
+    // Destination port must be >0.
+    EXPECT_FALSE(forward_targets_are_valid("tcp:8000", "tcp:-1", &error));
+    EXPECT_FALSE(forward_targets_are_valid("tcp:8000", "tcp:0", &error));
+
+    // Port must be a number.
+    EXPECT_FALSE(forward_targets_are_valid("tcp:", "tcp:9000", &error));
+    EXPECT_FALSE(forward_targets_are_valid("tcp:a", "tcp:9000", &error));
+    EXPECT_FALSE(forward_targets_are_valid("tcp:22x", "tcp:9000", &error));
+    EXPECT_FALSE(forward_targets_are_valid("tcp:8000", "tcp:", &error));
+    EXPECT_FALSE(forward_targets_are_valid("tcp:8000", "tcp:a", &error));
+    EXPECT_FALSE(forward_targets_are_valid("tcp:8000", "tcp:22x", &error));
+}