Implement ImmutableMapDuplicateKeyStrategy for obvious map construction

baseline-error-prone/src/main/java/com/palantir/baseline/errorprone/ImmutableMapDuplicateKeyStrategy.java

@@ -0,0 +1,56 @@
+/*
+ * (c) Copyright 2022 Palantir Technologies Inc. All rights reserved.
+ *
+ * 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.palantir.baseline.errorprone;
+
+import com.google.auto.service.AutoService;
+import com.google.common.collect.ImmutableMap;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.fixes.SuggestedFixes;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.google.errorprone.matchers.method.MethodMatchers;
+import com.sun.source.tree.ExpressionTree;
+import com.sun.source.tree.MethodInvocationTree;
+
+@AutoService(BugChecker.class)
+@BugPattern(
+        link = "https://github.com/palantir/gradle-baseline#baseline-error-prone-checks",
+        linkType = BugPattern.LinkType.CUSTOM,
+        severity = BugPattern.SeverityLevel.WARNING,
+        summary = "ImmutableMap.Builder.build() has non-obvious behavior, throwing on duplicate keys."
+                + " Please use 'buildKeepingLast()' or 'buildOrThrow()' for more obvious behavior.")
+public final class ImmutableMapDuplicateKeyStrategy extends BugChecker
+        implements BugChecker.MethodInvocationTreeMatcher {
+
+    private static final Matcher<ExpressionTree> MATCHER = MethodMatchers.instanceMethod()
+            .onDescendantOf(ImmutableMap.Builder.class.getCanonicalName())
+            .named("build")
+            .withNoParameters();
+
+    @Override
+    public Description matchMethodInvocation(MethodInvocationTree tree, VisitorState state) {
+        if (MATCHER.matches(tree, state)) {
+            // Update to the same functionality with a more descriptive name
+            return buildDescription(tree)
+                    .addFix(SuggestedFixes.renameMethodInvocation(tree, "buildOrThrow", state))
+                    .build();
+        }
+        return Description.NO_MATCH;
+    }
+}

baseline-error-prone/src/test/java/com/palantir/baseline/errorprone/ImmutableMapDuplicateKeyStrategyTest.java

@@ -0,0 +1,70 @@
+/*
+ * (c) Copyright 2022 Palantir Technologies Inc. All rights reserved.
+ *
+ * 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.palantir.baseline.errorprone;
+
+import com.google.common.collect.ImmutableMap;
+import com.google.common.collect.ImmutableSortedMap;
+import org.junit.jupiter.api.Test;
+
+class ImmutableMapDuplicateKeyStrategyTest {
+
+    @Test
+    void testImmutableMap() {
+        helper().addInputLines(
+                        "Test.java",
+                        "import " + ImmutableMap.class.getName() + ";",
+                        "class Test {",
+                        "  Object f(ImmutableMap.Builder<String, String> b) {",
+                        "    return b.build();",
+                        "  }",
+                        "}")
+                .addOutputLines(
+                        "Test.java",
+                        "import " + ImmutableMap.class.getName() + ";",
+                        "class Test {",
+                        "  Object f(ImmutableMap.Builder<String, String> b) {",
+                        "    return b.buildOrThrow();",
+                        "  }",
+                        "}")
+                .doTest();
+    }
+
+    @Test
+    void testImmutableSortedMap() {
+        helper().addInputLines(
+                        "Test.java",
+                        "import " + ImmutableSortedMap.class.getName() + ";",
+                        "class Test {",
+                        "  Object f(ImmutableSortedMap.Builder<String, String> b) {",
+                        "    return b.build();",
+                        "  }",
+                        "}")
+                .addOutputLines(
+                        "Test.java",
+                        "import " + ImmutableSortedMap.class.getName() + ";",
+                        "class Test {",
+                        "  Object f(ImmutableSortedMap.Builder<String, String> b) {",
+                        "    return b.buildOrThrow();",
+                        "  }",
+                        "}")
+                .doTest();
+    }
+
+    private RefactoringValidator helper() {
+        return RefactoringValidator.of(ImmutableMapDuplicateKeyStrategy.class, getClass());
+    }
+}

changelog/@unreleased/pr-2416.v2.yml

@@ -0,0 +1,7 @@
+type: improvement
+improvement:
+  description: Implement ImmutableMapDuplicateKeyStrategy for obvious map construction.
+    By default we suggest replacing `build()` with the more descriptive `buildOrThrow()`,
+    however `buildKeepingLast()` may be the original intent in some cases.
+  links:
+  - https://github.com/palantir/gradle-baseline/pull/2416

gradle-baseline-java/src/main/groovy/com/palantir/baseline/extensions/BaselineErrorProneExtension.java

@@ -43,6 +43,7 @@ public class BaselineErrorProneExtension {
             "ExtendsErrorOrThrowable",
             "FinalClass",
             "IllegalSafeLoggingArgument",
+            "ImmutableMapDuplicateKeyStrategy",
             "ImmutablesStyle",
             "ImplicitPublicBuilderConstructor",
             "JavaTimeDefaultTimeZone",