[CI] Enable function cognitive complexity check in clang-tidy (#165)

Author: aobolensk

.clang-tidy

@@ -23,7 +23,6 @@ Checks: >
   -modernize-loop-convert,
   -modernize-use-nodiscard,
   -modernize-use-trailing-return-type,
-  -readability-function-cognitive-complexity,
   -readability-identifier-length,
   -readability-magic-numbers,
   -readability-named-parameter
@@ -79,3 +78,5 @@ CheckOptions:
     value:           lower_case
   - key:             readability-identifier-naming.IgnoreMainLikeFunctions
     value:           1
+  - key:             readability-function-cognitive-complexity.Threshold
+    value:           25  # default: 25

modules/ref/most_different_neighbor_elements/func_tests/ref_tests.cpp

@@ -138,11 +138,9 @@ TEST(most_different_neighbor_elements, check_int64_t) {
   for (size_t i = 0; i < in.size(); i++) {
     if (i % 3 == 0) {
       in[i] = 10;
-    }
-    if (i % 3 == 1) {
+    } else if (i % 3 == 1) {
       in[i] = 30;
-    }
-    if (i % 3 == 2) {
+    } else {  // (i % 3 == 2)
       in[i] = 70;
     }
   }

modules/ref/nearest_neighbor_elements/func_tests/ref_tests.cpp

@@ -138,11 +138,9 @@ TEST(nearest_neighbor_elements, check_int64_t) {
   for (size_t i = 0; i < in.size(); i++) {
     if (i % 3 == 0) {
       in[i] = 10;
-    }
-    if (i % 3 == 1) {
+    } else if (i % 3 == 1) {
       in[i] = 30;
-    }
-    if (i % 3 == 2) {
+    } else {  // (i % 3 == 2)
       in[i] = 70;
     }
   }