SideEffectChecker: mark all assert* methods as having exceptional effect

SideEffectChecker#mayHaveExceptionalSideEffect extracted
Fixes IDEA-174418

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/bugs/IgnoreResultOfCallInspectionBase.java

@@ -17,7 +17,6 @@ package com.siyeh.ig.bugs;
 
 import com.intellij.codeInsight.AnnotationUtil;
 import com.intellij.codeInspection.dataFlow.ControlFlowAnalyzer;
-import com.intellij.codeInspection.dataFlow.MethodContract;
 import com.intellij.openapi.roots.ProjectFileIndex;
 import com.intellij.openapi.util.InvalidDataException;
 import com.intellij.openapi.util.WriteExternalException;
@@ -34,6 +33,7 @@ import com.siyeh.ig.BaseInspectionVisitor;
 import com.siyeh.ig.callMatcher.CallMatcher;
 import com.siyeh.ig.psiutils.LibraryUtil;
 import com.siyeh.ig.psiutils.MethodMatcher;
+import com.siyeh.ig.psiutils.SideEffectChecker;
 import org.intellij.lang.annotations.Pattern;
 import org.jdom.Element;
 import org.jetbrains.annotations.NotNull;
@@ -228,8 +228,7 @@ public class IgnoreResultOfCallInspectionBase extends BaseInspection {
       final boolean honorInferred = Registry.is("ide.ignore.call.result.inspection.honor.inferred.pure");
       if (!honorInferred && AnnotationUtil.isInferredAnnotation(anno)) return false;
       return Boolean.TRUE.equals(AnnotationUtil.getBooleanAttributeValue(anno, "pure")) &&
-             ControlFlowAnalyzer.getMethodCallContracts(method, null).stream()
-               .noneMatch(c -> c.getReturnValue() == MethodContract.ValueConstraint.THROW_EXCEPTION);
+             !SideEffectChecker.mayHaveExceptionalSideEffect(method);
     }
 
     private void registerMethodCallOrRefError(PsiExpression call, PsiClass aClass) {

plugins/InspectionGadgets/InspectionGadgetsAnalysis/src/com/siyeh/ig/psiutils/SideEffectChecker.java

@@ -126,11 +126,7 @@ public class SideEffectChecker {
     protected boolean isPure(PsiMethod method) {
       if (method == null) return false;
       if (PropertyUtil.isSimpleGetter(method)) return true;
-      if (ControlFlowAnalyzer.isPure(method)) {
-        return ControlFlowAnalyzer.getMethodContracts(method).stream()
-          .noneMatch(mc -> mc.returnValue == MethodContract.ValueConstraint.THROW_EXCEPTION);
-      }
-      return false;
+      return ControlFlowAnalyzer.isPure(method) && !mayHaveExceptionalSideEffect(method);
     }
 
     @Override
@@ -202,6 +198,21 @@ public class SideEffectChecker {
     }
   }
 
+  /**
+   * Returns true if given method function is likely to throw an exception (e.g. "assertEquals"). In some cases this means that
+   * the method call should be preserved in source code even if it's pure (i.e. does not change the program state).
+   *
+   * @param method a method to check
+   * @return true if the method has exceptional side effect
+   */
+  public static boolean mayHaveExceptionalSideEffect(PsiMethod method) {
+    if (method.getName().startsWith("assert")) {
+      return true;
+    }
+    return ControlFlowAnalyzer.getMethodContracts(method).stream()
+      .anyMatch(mc -> mc.returnValue == MethodContract.ValueConstraint.THROW_EXCEPTION);
+  }
+
   private static boolean isSideEffectFreeConstructor(@NotNull PsiNewExpression newExpression) {
     PsiJavaCodeReferenceElement classReference = newExpression.getClassReference();
     PsiClass aClass = classReference == null ? null : (PsiClass)classReference.resolve();

plugins/InspectionGadgets/test/com/siyeh/igtest/bugs/mismatched_string_builder_query_update/MismatchedStringBuilderQueryUpdate.java

@@ -19,6 +19,13 @@ import java.util.*;
 
 public class MismatchedStringBuilderQueryUpdate {
 
+  public void testAssert() {
+    StringBuilder finished = new StringBuilder();
+
+    finished.append("3 ");
+    Assert.assertEquals("expected", finished.toString());
+  }
+
   void foo() {
     final StringBuilder b = new StringBuilder();
     b.append("");
@@ -115,3 +122,8 @@ class EnumConstant {
     SomeEnum(StringBuilder sb) {}
   }
 }
+class Assert {
+  static Object assertEquals(Object a, Object b) {
+    return a;
+  }
+}