From 9af238586117768be09ed2cd8ae98128991f6513 Mon Sep 17 00:00:00 2001
From: Vincent Koeman <vincent.koeman@teampicnic.com>
Date: Fri, 6 Oct 2023 17:24:34 +0200
Subject: [PATCH] Introduce `JUnitParameterizedMethodDeclaration` bug checker

---
 .../JUnitParameterizedMethodDeclaration.java  | 48 +++++++++++++++++++
 ...nitParameterizedMethodDeclarationTest.java | 30 ++++++++++++
 2 files changed, 78 insertions(+)
 create mode 100644 error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitParameterizedMethodDeclaration.java
 create mode 100644 error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/JUnitParameterizedMethodDeclarationTest.java

diff --git a/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitParameterizedMethodDeclaration.java b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitParameterizedMethodDeclaration.java
new file mode 100644
index 00000000000..4ba2eec526b
--- /dev/null
+++ b/error-prone-contrib/src/main/java/tech/picnic/errorprone/bugpatterns/JUnitParameterizedMethodDeclaration.java
@@ -0,0 +1,48 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import static com.google.errorprone.BugPattern.LinkType.CUSTOM;
+import static com.google.errorprone.BugPattern.SeverityLevel.SUGGESTION;
+import static com.google.errorprone.BugPattern.StandardTags.SIMPLIFICATION;
+import static com.google.errorprone.matchers.ChildMultiMatcher.MatchType.AT_LEAST_ONE;
+import static com.google.errorprone.matchers.Matchers.annotations;
+import static com.google.errorprone.matchers.Matchers.isType;
+import static tech.picnic.errorprone.bugpatterns.util.Documentation.BUG_PATTERNS_BASE_URL;
+
+import com.google.auto.service.AutoService;
+import com.google.errorprone.BugPattern;
+import com.google.errorprone.VisitorState;
+import com.google.errorprone.bugpatterns.BugChecker;
+import com.google.errorprone.bugpatterns.BugChecker.MethodTreeMatcher;
+import com.google.errorprone.matchers.Description;
+import com.google.errorprone.matchers.Matcher;
+import com.sun.source.tree.MethodTree;
+
+/**
+ * A {@link BugChecker} that flags test methods using {@link
+ * org.junit.jupiter.params.ParameterizedTest} without actually having any arguments.
+ */
+@AutoService(BugChecker.class)
+@BugPattern(
+    summary = "JUnit parameterized test used without arguments",
+    link = BUG_PATTERNS_BASE_URL + "JUnitParameterizedMethodDeclaration",
+    linkType = CUSTOM,
+    severity = SUGGESTION,
+    tags = SIMPLIFICATION)
+public final class JUnitParameterizedMethodDeclaration extends BugChecker
+    implements MethodTreeMatcher {
+  private static final long serialVersionUID = 1L;
+  private static final Matcher<MethodTree> IS_PARAMETERIZED_TEST =
+      annotations(AT_LEAST_ONE, isType("org.junit.jupiter.params.ParameterizedTest"));
+
+  /** Instantiates a new {@link JUnitParameterizedMethodDeclaration} instance. */
+  public JUnitParameterizedMethodDeclaration() {}
+
+  @Override
+  public Description matchMethod(MethodTree tree, VisitorState state) {
+    if (IS_PARAMETERIZED_TEST.matches(tree, state) && tree.getParameters().isEmpty()) {
+      return describeMatch(tree);
+    }
+
+    return Description.NO_MATCH;
+  }
+}
diff --git a/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/JUnitParameterizedMethodDeclarationTest.java b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/JUnitParameterizedMethodDeclarationTest.java
new file mode 100644
index 00000000000..14e26f79693
--- /dev/null
+++ b/error-prone-contrib/src/test/java/tech/picnic/errorprone/bugpatterns/JUnitParameterizedMethodDeclarationTest.java
@@ -0,0 +1,30 @@
+package tech.picnic.errorprone.bugpatterns;
+
+import com.google.errorprone.CompilationTestHelper;
+import org.junit.jupiter.api.Test;
+
+final class JUnitParameterizedMethodDeclarationTest {
+  @Test
+  void identification() {
+    CompilationTestHelper.newInstance(JUnitParameterizedMethodDeclaration.class, getClass())
+        .addSourceLines(
+            "A.java",
+            "import org.junit.jupiter.api.Test;",
+            "import org.junit.jupiter.params.ParameterizedTest;",
+            "",
+            "class A {",
+            "  @Test",
+            "  void test() {}",
+            "",
+            "  @ParameterizedTest",
+            "  // BUG: Diagnostic contains:",
+            "  void badParameterizedTest() {}",
+            "",
+            "  @ParameterizedTest",
+            "  void goodParameterizedTest(Object someArgument) {}",
+            "",
+            "  void nonTest() {}",
+            "}")
+        .doTest();
+  }
+}