From e8ce8ce2c6070dc13bb7acbeb23cbaa22d8d01cf Mon Sep 17 00:00:00 2001
From: chrisly42 <chrisly@platon42.de>
Date: Mon, 17 Feb 2020 18:33:11 +0100
Subject: [PATCH] BogusAssertionInspection will no longer warn if the
 expression contains method calls and now tries to avoid valid hashCode() and
 equals() tests.

---
 README.md                                     | 13 +++++
 build.gradle                                  |  8 +++-
 .../inspections/BogusAssertionInspection.kt   | 48 +++++++++++++++++--
 .../BogusAssertionInspectionTest.kt           |  1 +
 .../BogusAssertion/BogusAssertionBefore.java  | 22 +++++++++
 5 files changed, 86 insertions(+), 6 deletions(-)

diff --git a/README.md b/README.md
index 8ba4428..97ca2c5 100644
--- a/README.md
+++ b/README.md
@@ -549,6 +549,14 @@ You can toggle the various inspections in the Settings/Editor/Inspections in the
   assertThat(map).hasSameSizeAs(map);
   ```
 
+  Note that expressions with method calls will not cause a warning as the method call might have side effects
+  that result in the assertion not being bogus at all.
+
+  If the assertions is either ```isEqualTo()``` or ```hasSameHashCodeAs()``` it may be checking custom
+  ```equals()``` or ```hashCode()``` behavior. If the test method name containing the statement has a
+  name that contains 'equal' or 'hashcode' (case insensitive), the warning will be weakened to information
+  level.
+
 - ImplicitAssertion
 
   Detects and removes implicit use of ```isNotNull()```, ```isNotEmpty()``` and
@@ -776,6 +784,11 @@ Feel free to use the code (in package ```de.platon42.intellij.jupiter```) for yo
 
 ## Changelog
 
+#### V1.9 (unreleased)
+- BogusAssertion inspection will no longer warn if the expression contains method calls.
+  Moreover, for assertions of ```isEqualTo()``` and ```hasSameHashCodeAs()```, AND if the containing method name contains 'equal' or 'hashcode',
+  the warning will be reduced to information level as the assertion may be testing ```equals()``` or ```hashCode()``` for validity.
+
 #### V1.8 (14-Feb-20) Valentine Edition
 - Maintenance. Removed experimental API use. Updated dependencies. Fixed testing problems introduced with IntelliJ IDEA 2019.3
 - Added new TwistedAssertion inspection that will warn about assertions with the actual expression being a constant indicating
diff --git a/build.gradle b/build.gradle
index 21974c9..1b44ca2 100644
--- a/build.gradle
+++ b/build.gradle
@@ -7,7 +7,7 @@ plugins {
 }
 
 group 'de.platon42'
-version '1.8'
+version '1.9'
 
 repositories {
     mavenCentral()
@@ -43,6 +43,12 @@ intellij {
 
 patchPluginXml {
     changeNotes """
+  <h4>V1.9 (unreleased)</h4>
+    <ul>
+      <li>BogusAssertion inspection will no longer warn if the expression contains method calls.
+          Moreover, for assertions of isEqualTo() and hasSameHashCodeAs(), AND if the containing method name contains 'equal' or 'hashcode',
+          the warning will be reduced to information level as the assertion may be testing equals() or hashCode() for validity.
+    </ul>
   <h4>V1.8 (14-Feb-20) Valentine Edition</h4>
     <ul>
       <li>Maintenance. Removed experimental API use. Updated dependencies. Fixed testing problems introduced with IntelliJ IDEA 2019.3.x
diff --git a/src/main/java/de/platon42/intellij/plugins/cajon/inspections/BogusAssertionInspection.kt b/src/main/java/de/platon42/intellij/plugins/cajon/inspections/BogusAssertionInspection.kt
index 7a332f1..3b4c59b 100644
--- a/src/main/java/de/platon42/intellij/plugins/cajon/inspections/BogusAssertionInspection.kt
+++ b/src/main/java/de/platon42/intellij/plugins/cajon/inspections/BogusAssertionInspection.kt
@@ -1,10 +1,8 @@
 package de.platon42.intellij.plugins.cajon.inspections
 
+import com.intellij.codeInspection.ProblemHighlightType
 import com.intellij.codeInspection.ProblemsHolder
-import com.intellij.psi.JavaElementVisitor
-import com.intellij.psi.PsiElementVisitor
-import com.intellij.psi.PsiExpressionStatement
-import com.intellij.psi.PsiMethodCallExpression
+import com.intellij.psi.*
 import com.intellij.psi.util.PsiTreeUtil
 import com.siyeh.ig.callMatcher.CallMatcher
 import com.siyeh.ig.psiutils.EquivalenceChecker
@@ -15,6 +13,7 @@ class BogusAssertionInspection : AbstractAssertJInspection() {
     companion object {
         private const val DISPLAY_NAME = "Bogus assertion due to same actual and expected expressions"
         private const val ACTUAL_IS_EQUAL_TO_EXPECTED_MESSAGE = "Actual expression in assertThat() is the same as expected"
+        private const val WEAK_ACTUAL_IS_EQUAL_TO_EXPECTED_MESSAGE = "Same actual and expected expression, but may be testing equals() or hashCode()"
 
         private val SAME_OBJECT =
             CallMatcher.instanceCall(
@@ -57,6 +56,12 @@ class BogusAssertionInspection : AbstractAssertJInspection() {
         private val SAME_OBJECT_ARRAY_CONTENTS =
             CallMatcher.instanceCall(AssertJClassNames.ABSTRACT_OBJECT_ARRAY_ASSERT_CLASSNAME, *ARRAY_METHODS).parameterCount(1)
 
+        private val HASHCODE_OR_IS_EQUAL_TO =
+            CallMatcher.instanceCall(
+                AssertJClassNames.ASSERT_INTERFACE,
+                MethodNames.IS_EQUAL_TO, "hasSameHashCodeAs"
+            ).parameterCount(1)
+
         private val SAME_ENUMERABLE_CONTENTS =
             CallMatcher.instanceCall(
                 AssertJClassNames.ENUMERABLE_ASSERT_INTERFACE,
@@ -130,9 +135,42 @@ class BogusAssertionInspection : AbstractAssertJInspection() {
                     .filter(SAME_ACTUAL_AND_EXPECTED_MATCHERS::test)
                     .any { equivalenceChecker.expressionsAreEquivalent(actualExpression, it.firstArg) }
                 if (isSameExpression) {
-                    holder.registerProblem(statement, ACTUAL_IS_EQUAL_TO_EXPECTED_MESSAGE)
+                    if (!hasExpressionWithSideEffects(actualExpression)) {
+                        if (allCalls.any(HASHCODE_OR_IS_EQUAL_TO::test)) {
+                            val method = PsiTreeUtil.getParentOfType(statement, PsiMethod::class.java, true)
+                            val methodName = method?.name
+                            if ((methodName != null)
+                                && ((methodName.contains("equal", ignoreCase = true) || methodName.contains("hashcode", ignoreCase = true)))
+                            ) {
+                                if (isOnTheFly) {
+                                    holder.registerProblem(statement, WEAK_ACTUAL_IS_EQUAL_TO_EXPECTED_MESSAGE, ProblemHighlightType.INFORMATION)
+                                }
+                                return
+                            }
+                        }
+                        holder.registerProblem(statement, ACTUAL_IS_EQUAL_TO_EXPECTED_MESSAGE)
+                    }
                 }
             }
+
+            private fun hasExpressionWithSideEffects(actualExpression: PsiExpression): Boolean {
+                var result = false
+                PsiTreeUtil.processElements(actualExpression) { element ->
+                    val matched = when (element) {
+                        is PsiUnaryExpression -> (element.operationTokenType == JavaTokenType.PLUSPLUS)
+                                || (element.operationTokenType == JavaTokenType.MINUSMINUS)
+                        is PsiMethodCallExpression -> true
+                        else -> false
+                    }
+                    if (matched) {
+                        result = true
+                        false
+                    } else {
+                        true
+                    }
+                }
+                return result
+            }
         }
     }
 }
\ No newline at end of file
diff --git a/src/test/java/de/platon42/intellij/plugins/cajon/inspections/BogusAssertionInspectionTest.kt b/src/test/java/de/platon42/intellij/plugins/cajon/inspections/BogusAssertionInspectionTest.kt
index d099dd5..5c3cc75 100644
--- a/src/test/java/de/platon42/intellij/plugins/cajon/inspections/BogusAssertionInspectionTest.kt
+++ b/src/test/java/de/platon42/intellij/plugins/cajon/inspections/BogusAssertionInspectionTest.kt
@@ -14,5 +14,6 @@ internal class BogusAssertionInspectionTest : AbstractCajonTest() {
         myFixture.enableInspections(BogusAssertionInspection::class.java)
         myFixture.configureByFile("BogusAssertionBefore.java")
         assertHighlightings(myFixture, 14 * 9 + 10 + 12 + 8, "Actual expression in assertThat() is the same as expected")
+        assertHighlightings(myFixture, 3, "Same actual and expected expression, but may be testing equals() or hashCode()")
     }
 }
\ No newline at end of file
diff --git a/src/test/resources/inspections/BogusAssertion/BogusAssertionBefore.java b/src/test/resources/inspections/BogusAssertion/BogusAssertionBefore.java
index 6980b31..f3dc502 100644
--- a/src/test/resources/inspections/BogusAssertion/BogusAssertionBefore.java
+++ b/src/test/resources/inspections/BogusAssertion/BogusAssertionBefore.java
@@ -1,3 +1,4 @@
+import java.io.File;
 import java.util.*;
 
 import static org.assertj.core.api.Assertions.assertThat;
@@ -190,7 +191,28 @@ public class BogusAssertions {
 
         assertThat(bar).isEqualTo(string);
 
+        assertThat(new Random().nextBoolean()).isEqualTo(new Random().nextBoolean());
+        assertThat(generateString()).isEqualTo(generateString());
+
+        int number = 4;
+        assertThat(number++).isEqualTo(number++);
+        assertThat(number++).isEqualTo(number++);
+
         org.junit.Assert.assertThat(list, null);
         fail("oh no!");
     }
+
+    private void test_equals() {
+        assertThat("foo").isEqualTo("foo");
+        assertThat(new File("foo")).isEqualTo(new File("foo"));
+    }
+
+    private void test_HasHCode() {
+        assertThat("foo").hasSameHashCodeAs("foo");
+    }
+
+    private String generateString()
+    {
+        return "foo";
+    }
 }