clang-tidy: Enable bugprone-assignment-in-if

Modified code to address issues flagged by this check.

Tested: Build and unit tests passed successfully.

Change-Id: I3b5f7c29fa38fc39da06e27488d70866006695c9
Signed-off-by: Jayanth Othayoth <ojayanth@gmail.com>
diff --git a/.clang-tidy b/.clang-tidy
index df0114b..3322c6f 100644
--- a/.clang-tidy
+++ b/.clang-tidy
@@ -2,6 +2,7 @@
 -*,
 bugprone-argument-comment,
 bugprone-assert-side-effect,
+bugprone-assignment-in-if,
 bugprone-bad-signal-to-kill-thread,
 bugprone-bool-pointer-implicit-conversion,
 bugprone-branch-clone,
diff --git a/certificate.cpp b/certificate.cpp
index 67c5aad..5e4ef9c 100644
--- a/certificate.cpp
+++ b/certificate.cpp
@@ -510,12 +510,12 @@
     issuer(issuerBuffer);
 
     std::vector<std::string> keyUsageList;
-    ASN1_BIT_STRING* usage;
 
     // Go through each usage in the bit string and convert to
     // corresponding string value
-    if ((usage = static_cast<ASN1_BIT_STRING*>(
-             X509_get_ext_d2i(&cert, NID_key_usage, nullptr, nullptr))))
+    ASN1_BIT_STRING* usage = static_cast<ASN1_BIT_STRING*>(
+        X509_get_ext_d2i(&cert, NID_key_usage, nullptr, nullptr));
+    if (usage != nullptr)
     {
         for (auto i = 0; i < usage->length; ++i)
         {
@@ -530,9 +530,9 @@
         }
     }
 
-    EXTENDED_KEY_USAGE* extUsage;
-    if ((extUsage = static_cast<EXTENDED_KEY_USAGE*>(
-             X509_get_ext_d2i(&cert, NID_ext_key_usage, nullptr, nullptr))))
+    EXTENDED_KEY_USAGE* extUsage = static_cast<EXTENDED_KEY_USAGE*>(
+        X509_get_ext_d2i(&cert, NID_ext_key_usage, nullptr, nullptr));
+    if (extUsage == nullptr)
     {
         for (int i = 0; i < sk_ASN1_OBJECT_num(extUsage); i++)
         {
diff --git a/certs_manager.cpp b/certs_manager.cpp
index 9d828c1..dc991d5 100644
--- a/certs_manager.cpp
+++ b/certs_manager.cpp
@@ -904,9 +904,9 @@
         }
     }
 
-    FILE* fp = nullptr;
+    FILE* fp = std::fopen(filePath.c_str(), "w");
 
-    if ((fp = std::fopen(filePath.c_str(), "w")) == nullptr)
+    if (fp == nullptr)
     {
         lg2::error(
             "Error opening the file to write the CSR, FILENAME:{FILENAME}",