Fix presenter timezone tests on hosts with stale /tmp fixtures

include/opencattus/services/timezone.h

@@ -8,7 +8,9 @@
 
 #include <list>
 #include <map>
+#include <optional>
 #include <string>
+#include <utility>
 #include <vector>
 
 /**
@@ -70,6 +72,37 @@ class Timezone {
      */
     std::multimap<std::string, std::string> fetchAvailableTimezones();
 
+#ifdef BUILD_TESTING
+    // Test-only seam: when set, fetchAvailableTimezones() parses the override
+    // lines as the zone1970.tab contents instead of reading the host's
+    // /usr/share/zoneinfo/zone1970.tab. An empty override still exercises the
+    // timedatectl fallback through the runner singleton. Bare CI hosts carry
+    // real tzdata state that would otherwise leak into tests expecting
+    // synthetic timezones. Use Timezone::ScopedTestZone1970Tab for RAII
+    // teardown rather than poking this directly.
+    static std::optional<std::vector<std::string>> s_testZone1970Override;
+
+    class ScopedTestZone1970Tab {
+    public:
+        explicit ScopedTestZone1970Tab(std::vector<std::string> lines)
+            : m_previous(std::move(s_testZone1970Override))
+        {
+            s_testZone1970Override = std::move(lines);
+        }
+        ScopedTestZone1970Tab(const ScopedTestZone1970Tab&) = delete;
+        ScopedTestZone1970Tab& operator=(const ScopedTestZone1970Tab&) = delete;
+        ScopedTestZone1970Tab(ScopedTestZone1970Tab&&) = delete;
+        ScopedTestZone1970Tab& operator=(ScopedTestZone1970Tab&&) = delete;
+        ~ScopedTestZone1970Tab()
+        {
+            s_testZone1970Override = std::move(m_previous);
+        }
+
+    private:
+        std::optional<std::vector<std::string>> m_previous;
+    };
+#endif
+
     void setTimezoneArea(std::string_view);
     std::string_view getTimezoneArea() const;
 

src/services/timezone.cpp

@@ -3,7 +3,6 @@
  * SPDX-License-Identifier: Apache-2.0
  */
 
-#include <cstdlib>
 #include <filesystem>
 #include <fmt/format.h>
 #include <fstream>
@@ -20,7 +19,6 @@
 using namespace opencattus;
 
 namespace {
-constexpr std::string_view zone1970TabEnv = "OPENCATTUS_ZONE1970_TAB";
 constexpr std::string_view zone1970TabPath = "/usr/share/zoneinfo/zone1970.tab";
 constexpr std::string_view timedatectlTimezoneCommand
     = "timedatectl list-timezones --no-pager";
@@ -68,19 +66,15 @@ void insertTimezone(
     timezones.insert({ tz.substr(0, slash), tz.substr(slash + 1) });
 }
 
-std::filesystem::path systemZone1970TabPath()
+std::vector<std::string> readZone1970Tab()
 {
-    if (const auto* overridePath = std::getenv(zone1970TabEnv.data());
-        overridePath != nullptr && std::string_view(overridePath).size() > 0) {
-        return overridePath;
+#ifdef BUILD_TESTING
+    if (Timezone::s_testZone1970Override.has_value()) {
+        return parseZone1970Tab(*Timezone::s_testZone1970Override);
     }
+#endif
 
-    return zone1970TabPath;
-}
-
-std::vector<std::string> readZone1970Tab()
-{
-    const auto path = systemZone1970TabPath();
+    const std::filesystem::path path { zone1970TabPath };
     std::ifstream file(path);
     if (!file.is_open()) {
         LOG_DEBUG(
@@ -103,6 +97,10 @@ std::vector<std::string> readZone1970Tab()
 }
 }
 
+#ifdef BUILD_TESTING
+std::optional<std::vector<std::string>> Timezone::s_testZone1970Override;
+#endif
+
 Timezone::Timezone()
     : m_availableTimezones { fetchAvailableTimezones() }
 {