a simple purity contract inference (IDEA-128879)

java/java-tests/testSrc/com/intellij/codeInspection/DataFlowInspectionTestSuite.java

@@ -30,6 +30,7 @@ public class DataFlowInspectionTestSuite {
     suite.addTestSuite(DataFlowInspectionAncientTest.class);
     suite.addTestSuite(ContractCheckTest.class);
     suite.addTestSuite(ContractInferenceFromSourceTest.class);
+    suite.addTestSuite(PurityInferenceFromSourceTest.class);
     suite.addTestSuite(SliceTreeTest.class);
     suite.addTestSuite(SliceBackwardTest.class);
     suite.addTestSuite(SmartTypeCompletionDfaTest.class);

java/java-tests/testSrc/com/intellij/codeInspection/PurityInferenceFromSourceTest.groovy

@@ -0,0 +1,128 @@
+/*
+ * Copyright 2000-2014 JetBrains s.r.o.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.intellij.codeInspection
+
+import com.intellij.codeInspection.dataFlow.PurityInference
+import com.intellij.testFramework.fixtures.LightCodeInsightFixtureTestCase
+/**
+ * @author peter
+ */
+class PurityInferenceFromSourceTest extends LightCodeInsightFixtureTestCase {
+
+  public void "test getter"() {
+    assertPure true, """
+Object getField() {
+  return field;
+}
+"""
+  }
+
+  public void "test setter"() {
+    assertPure false, """
+void setField(String s) {
+  field = s;
+}
+"""
+  }
+
+  public void "test unknown"() {
+    assertPure false, """
+int random() {
+  launchMissiles();
+  return 2;
+}
+"""
+  }
+
+  public void "test print"() {
+    assertPure false, """
+int random() {
+  System.out.println("hello");
+  return 2;
+}
+"""
+  }
+
+  public void "test local var assignment"() {
+    assertPure true, """
+int random(boolean b) {
+  int i = 4;
+  if (b) {
+    i = 2;
+  } else {
+    i++;
+  }
+  return i;
+}
+"""
+  }
+
+  public void "test local array var assignment"() {
+    assertPure true, """
+int[] randomArray() {
+  int[] i = new int[0];
+  i[0] = random();
+  return i;
+}
+int random() { return 2; }
+"""
+  }
+
+  public void "test field array assignment"() {
+    assertPure false, """
+int[] randomArray() {
+  i[0] = random();
+  return i;
+}
+int random() { return 2; }
+  int[] i = new int[0];
+"""
+  }
+
+  public void "test use explicit pure contract"() {
+    assertPure true, """
+int method() {
+  return smthPure();
+}
+@org.jetbrains.annotations.Contract(pure=true) native int smthPure();
+"""
+  }
+
+  public void "test don't analyze more than one call"() {
+    assertPure false, """
+int method() {
+  return smthPure(smthPure2());
+}
+int smthPure(int i) { return i; }
+int smthPure2() { return 42; }
+"""
+  }
+
+  public void "test don't analyze void methods"() {
+    assertPure false, """
+void method() {
+  smthPure();
+}
+int smthPure() { return 3; }
+"""
+  }
+
+  private void assertPure(boolean expected, String classBody) {
+    def clazz = myFixture.addClass("final class Foo { $classBody }")
+    assert expected == PurityInference.inferPurity(clazz.methods[0])
+  }
+
+}