test(readability-constant-operand-order): add CHECK-LEFT expectations for ok_eq

Author: saideepaksana

clang-tools-extra/test/clang-tidy/checkers/readability/constant-operand-order.cpp

@@ -0,0 +1,35 @@
+void ok_eq(int a) {
+  if (a == 0) {} // CHECK-MESSAGES-NOT: readability-constant-operand-order
+                 // CHECK-LEFT-MESSAGES: warning: constant operand should be on the Left side
+                 // CHECK-LEFT-FIXES: if (0 == a) {} //
+}
+
+
+void swap_eq(int a) {
+  if (0 == a) {} // CHECK-MESSAGES: warning: constant operand should be on the Right side
+                 // CHECK-FIXES: if (a == 0) {} //
+}
+
+void swap_asym(int a) {
+  if (0 < a) {}  // CHECK-MESSAGES: warning:
+                 // CHECK-FIXES: if (a > 0) {}  //
+}
+
+void null_ptr(int *p) {
+  if (nullptr == p) {} // CHECK-MESSAGES: warning:
+                       // CHECK-FIXES: if (p == nullptr) {} //
+}
+
+// No-fix when side effects:
+int g();
+void side_effects(int a) {
+  if (0 == g()) {} // CHECK-MESSAGES: warning:
+                   // CHECK-FIXES-NOT: if (g() == 0)
+}
+
+// Config variant: allow Left and only ==,!=
+void left_ok(int a) {
+  if (0 == a) {} // CHECK-MESSAGES: warning:
+                 // CHECK-FIXES: if (a == 0) {} //
+                 // CHECK-LEFT-MESSAGES-NOT: readability-constant-operand-order
+}