PY-49165 Add tests for PyPatternInspection and related quickfixes

GitOrigin-RevId: 0e35bd5d50e2d6b544cbd4467d184b6be21b7574

python/python-psi-impl/resources/messages/PyPsiBundle.properties

@@ -1370,7 +1370,7 @@ INSP.NAME.patterns=Invalid pattern in pattern matching
 INSP.patterns.pattern.can.be.simplified=Pattern can be simplified
 INSP.patterns.class.does.not.support.pattern.matching.with.positional.arguments=Class {0} does not support pattern matching with positional arguments
 INSP.patterns.too.many.positional.patterns.expected=Too many positional patterns, expected {0}
-INSP.patterns.attribute.already.specified.as.positional.pattern.at.position=Attribute ''{0}'' is already specified as positional pattern at position {1}1
+INSP.patterns.attribute.already.specified.as.positional.pattern.at.position=Attribute ''{0}'' is already specified as positional pattern at position {1}
 QFIX.simplify.as.pattern=Simplify 'as' pattern
 QFIX.NAME.remove.list.member=Remove list member
 QFIX.remove.pattern=Remove pattern

python/python-psi-impl/src/com/jetbrains/python/inspections/PyPatternInspection.kt

@@ -12,6 +12,7 @@ import com.intellij.psi.util.PsiTreeUtil
 import com.jetbrains.python.PyNames
 import com.jetbrains.python.PyPsiBundle
 import com.jetbrains.python.PyTokenTypes
+import com.jetbrains.python.documentation.PythonDocumentationProvider
 import com.jetbrains.python.psi.*
 import com.jetbrains.python.psi.impl.PyBuiltinCache
 import com.jetbrains.python.psi.impl.PyClassPatternImpl
@@ -83,7 +84,7 @@ private class PyPatternInspectionVisitor(holder: ProblemsHolder, context: TypeEv
       val keywordName = (keywordPattern as PyKeywordPattern).keyword
       val positionalIndex = positionalAttributeNames.indexOf(keywordName)
       if (positionalIndex >= 0) {
-        holder.problem(keywordPattern, PyPsiBundle.message("INSP.patterns.attribute.already.specified.as.positional.pattern.at.position", keywordName, positionalIndex))
+        holder.problem(keywordPattern, PyPsiBundle.message("INSP.patterns.attribute.already.specified.as.positional.pattern.at.position", keywordName, positionalIndex + 1))
           .fix(RemoveListMemberFix(keywordPattern))
           .register()
       }
@@ -96,12 +97,16 @@ private class PyPatternInspectionVisitor(holder: ProblemsHolder, context: TypeEv
       ?.findAssignedValue()
       ?.let { PyPsiUtils.flattenParens(it) } ?: return
     
-    val matchArgsType = myTypeEvalContext.getType(matchArgs)
-    val strType = PyBuiltinCache.getInstance(matchArgs).strType
-    val goodTuple = PyTupleType.createHomogeneous(matchArgs, strType)
+    val matchArgsType = myTypeEvalContext.getType(matchArgs) ?: return
+    val strType = PyBuiltinCache.getInstance(matchArgs).strType ?: return
+    val goodTuple = PyTupleType.createHomogeneous(matchArgs, strType) ?: return
     if (PyTypeChecker.match(goodTuple, matchArgsType, myTypeEvalContext)) return
     // __match_args__ must be a tuple[str, ...]
-    holder.problem(matchArgs, "__match_args__ must be a tuple[str, ...]").register()
+    holder.problem(matchArgs, PyPsiBundle.message(
+      "INSP.type.checker.expected.type.got.type.instead", 
+      PythonDocumentationProvider.getTypeName(goodTuple, myTypeEvalContext),
+      PythonDocumentationProvider.getTypeName(matchArgsType, myTypeEvalContext))
+    ).register()
   }
 }
 
@@ -167,7 +172,11 @@ class AddMatchArgsFix(element: PyClass) : PsiUpdateModCommandAction<PyClass>(ele
       ?.toList() ?: emptyList()
     
     val generator = PyElementGenerator.getInstance(pyClass.project)
-    val matchArgsValue = "(" + positionalArgs.joinToString(", ") { "'$it'" } + ")"
+    val matchArgsValue = positionalArgs.joinToString(
+      prefix = "(",
+      postfix = if (positionalArgs.size != 1) ")" else ",)",
+      separator = ", "
+    ) { "'$it'" }
     val matchArgsAssignment = generator.createFromText(
       LanguageLevel.forElement(pyClass),
       PyAssignmentStatement::class.java,

python/python-psi-impl/src/com/jetbrains/python/psi/impl/PyClassPatternImpl.java

@@ -137,15 +137,25 @@ public class PyClassPatternImpl extends PyElementImpl implements PyClassPattern,
   }
 
   public static @Nullable List<@NotNull String> getMatchArgs(@NotNull PyClassType type, @NotNull TypeEvalContext context) {
-    List<String> matchArgs = type.getPyClass().getOwnMatchArgs();
-    if (matchArgs == null) {
-      matchArgs = PyNamedTupleTypeProvider.Companion.getGeneratedMatchArgs(type, context);
-    }
-    if (matchArgs == null) {
-      matchArgs = PyDataclassTypeProvider.Companion.getGeneratedMatchArgs(type, context);
+    final PyClass cls = type.getPyClass();
+    // TODO: change to getMemberType, when PyLiteralType can be created without PyExpression
+    
+    List<String> matchArgs = cls.getOwnMatchArgs();
+    if (matchArgs != null) return matchArgs;
+
+    matchArgs = PyNamedTupleTypeProvider.Companion.getGeneratedMatchArgs(type, context);
+    if (matchArgs != null) return matchArgs;
+    matchArgs = PyDataclassTypeProvider.Companion.getGeneratedMatchArgs(type, context);
+    if (matchArgs != null) return matchArgs;
+
+    for (PyClassLikeType baseType : type.getSuperClassTypes(context)) {
+      if (baseType instanceof PyClassType baseClassType) {
+        final List<String> inherited = getMatchArgs(baseClassType, context);
+        if (inherited != null) return inherited;
+      }
     }
 
-    return matchArgs;
+    return null;
   }
 
   @Nullable

python/testData/quickFixes/PyAddMatchArgsFixTest/addMatchArgsBasic.py

@@ -0,0 +1,9 @@
+class Point:
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+def f(p):
+    match p:
+        case Point(<warning descr="Class Point does not support pattern matching with positional arguments"><caret>1</warning>, <warning descr="Class Point does not support pattern matching with positional arguments">2</warning>):
+            pass

python/testData/quickFixes/PyAddMatchArgsFixTest/addMatchArgsBasic_after.py

@@ -0,0 +1,11 @@
+class Point:
+    __match_args__ = ('x', 'y')
+
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+def f(p):
+    match p:
+        case Point(1, 2):
+            pass

python/testData/quickFixes/PyAddMatchArgsFixTest/addMatchArgsFilterAttributes.py

@@ -0,0 +1,9 @@
+class C:
+    def __init__(self, a, b, c):
+        self.a = a
+        # b is not assigned to instance attribute
+
+def f(obj):
+    match obj:
+        case C(<warning descr="Class C does not support pattern matching with positional arguments"><caret>1</warning>, <warning descr="Class C does not support pattern matching with positional arguments">2</warning>):
+            pass

python/testData/quickFixes/PyAddMatchArgsFixTest/addMatchArgsFilterAttributes_after.py

@@ -0,0 +1,11 @@
+class C:
+    __match_args__ = ('a',)
+
+    def __init__(self, a, b, c):
+        self.a = a
+        # b is not assigned to instance attribute
+
+def f(obj):
+    match obj:
+        case C(1, 2):
+            pass

python/testData/quickFixes/PyAddMatchArgsFixTest/addMatchArgsNoInit.py

@@ -0,0 +1,7 @@
+class Empty:
+    pass
+
+def f(obj):
+    match obj:
+        case Empty(<warning descr="Class Empty does not support pattern matching with positional arguments"><caret>1</warning>):
+            pass

python/testData/quickFixes/PyAddMatchArgsFixTest/addMatchArgsNoInit_after.py

@@ -0,0 +1,8 @@
+class Empty:
+    __match_args__ = ()
+    pass
+
+def f(obj):
+    match obj:
+        case Empty(1):
+            pass

python/testData/quickFixes/PyAddMatchArgsFixTest/addMatchArgsOnlySelf.py

@@ -0,0 +1,8 @@
+class OnlySelf:
+    def __init__(self):
+        pass
+
+def f(obj):
+    match obj:
+        case OnlySelf(<warning descr="Class OnlySelf does not support pattern matching with positional arguments"><caret>1</warning>):
+            pass

python/testData/quickFixes/PyAddMatchArgsFixTest/addMatchArgsOnlySelf_after.py

@@ -0,0 +1,10 @@
+class OnlySelf:
+    __match_args__ = ()
+
+    def __init__(self):
+        pass
+
+def f(obj):
+    match obj:
+        case OnlySelf(1):
+            pass

python/testData/quickFixes/PyRemovePatternFixTest/removeConflictingKeyword.py

@@ -0,0 +1,10 @@
+class Point:
+    __match_args__ = ("x", "y")
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+def f(p):
+    match p:
+        case Point(0, <warning descr="Attribute 'x' is already specified as positional pattern at position 1"><caret>x=0</warning>):
+            pass

python/testData/quickFixes/PyRemovePatternFixTest/removeConflictingKeyword_after.py

@@ -0,0 +1,10 @@
+class Point:
+    __match_args__ = ("x", "y")
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+def f(p):
+    match p:
+        case Point(0):
+            pass

python/testData/quickFixes/PyRemovePatternFixTest/removeLastExtraPositional.py

@@ -0,0 +1,10 @@
+class Point:
+    __match_args__ = ("x", "y")
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+def f(p):
+    match p:
+        case Point(a, b, <warning descr="Too many positional patterns, expected 2"><caret>c</warning>):
+            pass

python/testData/quickFixes/PyRemovePatternFixTest/removeLastExtraPositional_after.py

@@ -0,0 +1,10 @@
+class Point:
+    __match_args__ = ("x", "y")
+    def __init__(self, x, y):
+        self.x = x
+        self.y = y
+
+def f(p):
+    match p:
+        case Point(a, b):
+            pass

python/testData/quickFixes/PyRemovePatternFixTest/removeSingleExtraPositional.py

@@ -0,0 +1,7 @@
+class Z:
+    __match_args__ = ()
+
+def f(z):
+    match z:
+        case Z(<warning descr="Too many positional patterns, expected 0"><caret>1</warning>):
+            pass

python/testData/quickFixes/PyRemovePatternFixTest/removeSingleExtraPositional_after.py

@@ -0,0 +1,7 @@
+class Z:
+    __match_args__ = ()
+
+def f(z):
+    match z:
+        case Z():
+            pass

python/testData/quickFixes/PySimplifyAsPatternFixTest/simplifyIntAsPattern.py

@@ -0,0 +1,5 @@
+x = 42
+
+match x:
+    case <weak_warning descr="Pattern can be simplified"><caret>int() as n</weak_warning>:
+        pass

python/testData/quickFixes/PySimplifyAsPatternFixTest/simplifyIntAsPattern_after.py

@@ -0,0 +1,5 @@
+x = 42
+
+match x:
+    case int(n):
+        pass

python/testData/quickFixes/PySimplifyAsPatternFixTest/simplifyListAsPattern.py

@@ -0,0 +1,5 @@
+x = []
+
+match x:
+    case <weak_warning descr="Pattern can be simplified"><caret>list() as xs</weak_warning>:
+        pass

python/testData/quickFixes/PySimplifyAsPatternFixTest/simplifyListAsPattern_after.py

@@ -0,0 +1,5 @@
+x = []
+
+match x:
+    case list(xs):
+        pass

python/testSrc/com/jetbrains/python/inspections/PyPatternInspectionTest.java

@@ -55,16 +55,7 @@ def f(p):
   public void testInvalidMatchArgsType() {
     doTestByText("""
 class D:
-    __match_args__ = <warning descr="__match_args__ must be a tuple[str, ...]">42</warning>
-        """);
-  }
-
-  public void testUnknownAttributeInMatchArgs() {
-    doTestByText("""
-class E:
-    def __init__(self):
-        self.x = 0
-    __match_args__ = ("x", <warning descr="String 'y' does not refer to any instance attribute">'y'</warning>)
+    __match_args__ = <warning descr="Expected type 'tuple[str, ...]', got 'int' instead">42</warning>
         """);
   }
 
@@ -140,7 +131,7 @@ class A:
 
 def f(a):
     match a:
-        case A(x, <warning descr=\"Too many positional patterns, expected 1\">y</warning>, <warning descr=\"Too many positional patterns, expected 1\">z</warning>):
+        case A(x, <warning descr="Too many positional patterns, expected 1">y</warning>, <warning descr="Too many positional patterns, expected 1">z</warning>):
             pass
     """);
   }
@@ -150,7 +141,7 @@ def f(a):
 class D:
     def __init__(self):
         self.x = 0
-    __match_args__ = ("x", 1)
+    __match_args__ = (<warning descr="Expected type 'tuple[str, ...]', got 'tuple[str, int]' instead">"x", 1</warning>)
     """);
   }
 
@@ -233,6 +224,105 @@ class E:
     """);
   }
 
+  public void testSimplifyAsPatternInt() {
+    doTestByText("""
+x = 42
+
+match x:
+    case <weak_warning descr="Pattern can be simplified">int() as n</weak_warning>:
+        pass
+        """);
+  }
+
+  public void testSimplifyAsPatternDict() {
+    doTestByText("""
+x = {}
+
+match x:
+    case <weak_warning descr="Pattern can be simplified">dict() as d</weak_warning>:
+        pass
+        """);
+  }
+
+  public void testSimplifyAsPatternWithArgumentsNoWarning() {
+    doTestByText("""
+x = []
+
+match x:
+    case list(1, 2) as xs:
+        pass
+    """);
+  }
+
+  public void testMatchArgsInvalidTypeList() {
+    doTestByText("""
+class D:
+    __match_args__ = <warning descr="Expected type 'tuple[str, ...]', got 'list[str]' instead">["x", "y"]</warning>
+    """);
+  }
+
+  public void testMatchArgsInvalidTypeSet() {
+    doTestByText("""
+class D:
+    __match_args__ = <warning descr="Expected type 'tuple[str, ...]', got 'set[str]' instead">{"x", "y"}</warning>
+    """);
+  }
+
+  public void testMatchArgsInvalidTypeNone() {
+    doTestByText("""
+class D:
+    __match_args__ = <warning descr="Expected type 'tuple[str, ...]', got 'None' instead">None</warning>
+    """);
+  }
+
+  public void testMatchArgsInvalidTupleOfInts() {
+    doTestByText("""
+class D:
+    __match_args__ = (<warning descr="Expected type 'tuple[str, ...]', got 'tuple[int, int, int]' instead">1, 2, 3</warning>)
+    """);
+  }
+
+  public void testInheritedMatchArgsFromBase() {
+    doTestByText("""
+class Base:
+    __match_args__ = ("x",)
+    def __init__(self, x):
+        self.x = x
+
+class Derived(Base):
+    pass
+
+def f(d):
+    match d:
+        case Derived(1):
+            pass
+    """);
+  }
+
+  public void testClassWithoutInitNoWarning() {
+    doTestByText("""
+class C:
+    pass
+
+def f(c):
+    match c:
+        case C(a=1):
+            pass
+    """);
+  }
+
+  public void testEmptyClassWithPositionalPatternWarning() {
+    doTestByText("""
+class C:
+    pass
+
+def f(c):
+    match c:
+        case C(<warning descr="Class C does not support pattern matching with positional arguments">1</warning>):
+            pass
+    """);
+  }
+
   @NotNull
   @Override
   protected Class<? extends PyInspection> getInspectionClass() {

python/testSrc/com/jetbrains/python/quickFixes/PyAddMatchArgsFixTest.kt

@@ -0,0 +1,26 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.jetbrains.python.quickFixes
+
+import com.intellij.testFramework.TestDataPath
+import com.jetbrains.python.PyPsiBundle
+import com.jetbrains.python.PyQuickFixTestCase
+import com.jetbrains.python.inspections.PyPatternInspection
+
+@TestDataPath("\$CONTENT_ROOT/../testData/quickFixes/PyAddMatchArgsFixTest")
+class PyAddMatchArgsFixTest : PyQuickFixTestCase() {
+  fun testAddMatchArgsBasic() {
+    doQuickFixTest(PyPatternInspection::class.java, PyPsiBundle.message("QFIX.add.match.args.to.class", "Point"))
+  }
+
+  fun testAddMatchArgsFilterAttributes() {
+    doQuickFixTest(PyPatternInspection::class.java, PyPsiBundle.message("QFIX.add.match.args.to.class", "C"))
+  }
+
+  fun testAddMatchArgsNoInit() {
+    doQuickFixTest(PyPatternInspection::class.java, PyPsiBundle.message("QFIX.add.match.args.to.class", "Empty"))
+  }
+
+  fun testAddMatchArgsOnlySelf() {
+    doQuickFixTest(PyPatternInspection::class.java, PyPsiBundle.message("QFIX.add.match.args.to.class", "OnlySelf"))
+  }
+}

python/testSrc/com/jetbrains/python/quickFixes/PyRemovePatternFixTest.kt

@@ -0,0 +1,22 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.jetbrains.python.quickFixes
+
+import com.intellij.testFramework.TestDataPath
+import com.jetbrains.python.PyPsiBundle
+import com.jetbrains.python.PyQuickFixTestCase
+import com.jetbrains.python.inspections.PyPatternInspection
+
+@TestDataPath($$"$CONTENT_ROOT/../testData/quickFixes/PyRemovePatternFixTest")
+class PyRemovePatternFixTest : PyQuickFixTestCase() {
+  fun testRemoveLastExtraPositional() {
+    doQuickFixTest(PyPatternInspection::class.java, PyPsiBundle.message("QFIX.remove.pattern"))
+  }
+
+  fun testRemoveConflictingKeyword() {
+    doQuickFixTest(PyPatternInspection::class.java, PyPsiBundle.message("QFIX.remove.pattern"))
+  }
+
+  fun testRemoveSingleExtraPositional() {
+    doQuickFixTest(PyPatternInspection::class.java, PyPsiBundle.message("QFIX.remove.pattern"))
+  }
+}

python/testSrc/com/jetbrains/python/quickFixes/PySimplifyAsPatternFixTest.kt

@@ -0,0 +1,30 @@
+// Copyright 2000-2025 JetBrains s.r.o. and contributors. Use of this source code is governed by the Apache 2.0 license.
+package com.jetbrains.python.quickFixes
+
+import com.intellij.testFramework.TestDataPath
+import com.jetbrains.python.PyPsiBundle
+import com.jetbrains.python.PyQuickFixTestCase
+import com.jetbrains.python.inspections.PyPatternInspection
+
+@TestDataPath("\$CONTENT_ROOT/../testData/quickFixes/PySimplifyAsPatternFixTest")
+class PySimplifyAsPatternFixTest : PyQuickFixTestCase() {
+  fun testSimplifyListAsPattern() {
+    doQuickFixTest(PyPsiBundle.message("QFIX.simplify.as.pattern"))
+  }
+
+  fun testSimplifyIntAsPattern() {
+    doQuickFixTest(PyPsiBundle.message("QFIX.simplify.as.pattern"))
+  }
+
+  // Overriden to enable weak warnings
+  override fun doQuickFixTest(hint: String) {
+    val testFileName = getTestName(true)
+    myFixture.enableInspections(PyPatternInspection::class.java)
+    myFixture.configureByFile("$testFileName.py")
+    myFixture.checkHighlighting(false, false, true)
+    val intentionAction = myFixture.findSingleIntention(hint)
+    assertNotNull(intentionAction)
+    myFixture.launchAction(intentionAction)
+    myFixture.checkResultByFile(testFileName + "_after.py", true)
+  }
+}