SERVER-28436 Create a basic helper for enabling fail point in cpp test

5 files changed, 47 insertions, 4 deletions

diff --git a/src/mongo/db/commands/fail_point_cmd.cpp b/src/mongo/db/commands/fail_point_cmd.cpp
index 0f75d8c1316..ce8f1367f58 100644
--- a/src/mongo/db/commands/fail_point_cmd.cpp
+++ b/src/mongo/db/commands/fail_point_cmd.cpp
@@ -99,7 +99,7 @@ public:
         FailPointRegistry* registry = getGlobalFailPointRegistry();
         FailPoint* failPoint = registry->getFailPoint(failPointName);
 
-        if (failPoint == NULL) {
+        if (failPoint == nullptr) {
             errmsg = failPointName + " not found";
             return false;
         }
diff --git a/src/mongo/util/fail_point_registry.cpp b/src/mongo/util/fail_point_registry.cpp
index 7aea3357102..c428a29b349 100644
--- a/src/mongo/util/fail_point_registry.cpp
+++ b/src/mongo/util/fail_point_registry.cpp
@@ -55,7 +55,7 @@ Status FailPointRegistry::addFailPoint(const string& name, FailPoint* failPoint)
 }
 
 FailPoint* FailPointRegistry::getFailPoint(const string& name) const {
-    return mapFindWithDefault(_fpMap, name, static_cast<FailPoint*>(NULL));
+    return mapFindWithDefault(_fpMap, name, static_cast<FailPoint*>(nullptr));
 }
 
 void FailPointRegistry::freeze() {
diff --git a/src/mongo/util/fail_point_service.cpp b/src/mongo/util/fail_point_service.cpp
index 79768792564..e246cc9c16b 100644
--- a/src/mongo/util/fail_point_service.cpp
+++ b/src/mongo/util/fail_point_service.cpp
@@ -26,8 +26,9 @@
  *    then also delete it in the license file.
  */
 
-#include "mongo/util/fail_point_service.h"
+#include "mongo/platform/basic.h"
 
+#include "mongo/util/fail_point_service.h"
 
 namespace mongo {
 
@@ -52,4 +53,15 @@ MONGO_INITIALIZER_GENERAL(AllFailPointsRegistered, MONGO_NO_PREREQUISITES, MONGO
 FailPointRegistry* getGlobalFailPointRegistry() {
     return _fpRegistry.get();
 }
+
+FailPointEnableBlock::FailPointEnableBlock(const std::string& failPointName) {
+    _failPoint = getGlobalFailPointRegistry()->getFailPoint(failPointName);
+    invariant(_failPoint != nullptr);
+    _failPoint->setMode(FailPoint::alwaysOn);
+}
+
+FailPointEnableBlock::~FailPointEnableBlock() {
+    _failPoint->setMode(FailPoint::off);
 }
+
+}  // namespace mongo
diff --git a/src/mongo/util/fail_point_service.h b/src/mongo/util/fail_point_service.h
index d06960d0aac..331dc485e32 100644
--- a/src/mongo/util/fail_point_service.h
+++ b/src/mongo/util/fail_point_service.h
@@ -33,6 +33,8 @@
 
 namespace mongo {
 
+class FailPoint;
+
 /**
  * @return the global fail point registry.
  */
@@ -55,4 +57,17 @@ FailPointRegistry* getGlobalFailPointRegistry();
  * Convenience macro for defining a fail point in a header scope.
  */
 #define MONGO_FP_FORWARD_DECLARE(fp) extern FailPoint fp;
-}
+
+/**
+ * Convenience class for enabling a failpoint and disabling it as this goes out of scope.
+ */
+class FailPointEnableBlock {
+public:
+    FailPointEnableBlock(const std::string& failPointName);
+    ~FailPointEnableBlock();
+
+private:
+    FailPoint* _failPoint;
+};
+
+}  // namespace mongo
diff --git a/src/mongo/util/fail_point_test.cpp b/src/mongo/util/fail_point_test.cpp
index 5374b879da9..37bf8936f21 100644
--- a/src/mongo/util/fail_point_test.cpp
+++ b/src/mongo/util/fail_point_test.cpp
@@ -38,11 +38,14 @@
 #include "mongo/stdx/thread.h"
 #include "mongo/unittest/unittest.h"
 #include "mongo/util/fail_point.h"
+#include "mongo/util/fail_point_service.h"
 #include "mongo/util/log.h"
 #include "mongo/util/time_support.h"
 
+using mongo::getGlobalFailPointRegistry;
 using mongo::BSONObj;
 using mongo::FailPoint;
+using mongo::FailPointEnableBlock;
 namespace stdx = mongo::stdx;
 
 namespace mongo_test {
@@ -398,4 +401,17 @@ TEST(FailPoint, parseBSONValidDataSucceeds) {
                                              << BSON("a" << 1)));
     ASSERT_TRUE(swTuple.isOK());
 }
+
+TEST(FailPoint, FailPointBlockBasicTest) {
+    auto failPoint = getGlobalFailPointRegistry()->getFailPoint("dummy");
+
+    ASSERT_FALSE(failPoint->shouldFail());
+
+    {
+        FailPointEnableBlock dummyFp("dummy");
+        ASSERT_TRUE(failPoint->shouldFail());
+    }
+
+    ASSERT_FALSE(failPoint->shouldFail());
+}
 }