Factor out some common test code to a new test_utils library.

Test: atest netd_integration_test
Change-Id: I9a4145c3fde518f5cbe88444f617a881f110630c
diff --git a/tests/test_utils.cpp b/tests/test_utils.cpp
new file mode 100644
index 0000000..c0a157b
--- /dev/null
+++ b/tests/test_utils.cpp
@@ -0,0 +1,94 @@
+/*
+ * Copyright 2019 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ * test_utils.cpp - miscellaneous unit test utilities.
+ */
+
+#include <cstdio>
+#include <string>
+#include <vector>
+
+#include <android-base/stringprintf.h>
+
+#include "test_utils.h"
+
+#define IP_PATH "/system/bin/ip"
+
+using android::base::StringPrintf;
+
+int randomUid() {
+    return 100000 * arc4random_uniform(7) + 12000 + arc4random_uniform(3000);
+}
+
+std::vector<std::string> runCommand(const std::string& command) {
+    std::vector<std::string> lines;
+    FILE* f = popen(command.c_str(), "r");  // NOLINT(cert-env33-c)
+    if (f == nullptr) {
+        perror("popen");
+        return lines;
+    }
+
+    char* line = nullptr;
+    size_t bufsize = 0;
+    ssize_t linelen = 0;
+    while ((linelen = getline(&line, &bufsize, f)) >= 0) {
+        lines.push_back(std::string(line, linelen));
+        free(line);
+        line = nullptr;
+    }
+
+    pclose(f);
+    return lines;
+}
+
+std::vector<std::string> listIpRules(const char* ipVersion) {
+    std::string command = StringPrintf("%s %s rule list", IP_PATH, ipVersion);
+    return runCommand(command);
+}
+
+std::vector<std::string> listIptablesRule(const char* binary, const char* chainName) {
+    std::string command = StringPrintf("%s -w -n -L %s", binary, chainName);
+    return runCommand(command);
+}
+
+int iptablesRuleLineLength(const char* binary, const char* chainName) {
+    return listIptablesRule(binary, chainName).size();
+}
+
+bool iptablesRuleExists(const char* binary, const char* chainName,
+                        const std::string& expectedRule) {
+    std::vector<std::string> rules = listIptablesRule(binary, chainName);
+    for (const auto& rule : rules) {
+        if (rule.find(expectedRule) != std::string::npos) {
+            return true;
+        }
+    }
+    return false;
+}
+
+std::vector<std::string> listIpRoutes(const char* ipVersion, const char* table) {
+    std::string command = StringPrintf("%s %s route ls table %s", IP_PATH, ipVersion, table);
+    return runCommand(command);
+}
+
+bool ipRouteExists(const char* ipVersion, const char* table, const std::string& ipRoute) {
+    std::vector<std::string> routes = listIpRoutes(ipVersion, table);
+    for (const auto& route : routes) {
+        if (route.find(ipRoute) != std::string::npos) {
+            return true;
+        }
+    }
+    return false;
+}