Add conformance tests for Final dataclass fields (#1741)

Author: carljm

conformance/results/mypy/dataclasses_final.toml

@@ -0,0 +1,22 @@
+conformant = "Partial"
+notes = """
+Wrongly requires a Final dataclass field to be initialized at class level.
+Doesn't support Final nested inside ClassVar.
+"""
+conformance_automated = "Fail"
+errors_diff = """
+Line 16: Expected 1 errors
+Line 6: Unexpected errors ['dataclasses_final.py:6: error: Final name must be initialized with a value  [misc]']
+Line 8: Unexpected errors ['dataclasses_final.py:8: error: Final can be only used as an outermost qualifier in a variable annotation  [valid-type]']
+Line 13: Unexpected errors ['dataclasses_final.py:13: error: Expression is of type "Any", not "int"  [assert-type]']
+"""
+output = """
+dataclasses_final.py:6: error: Final name must be initialized with a value  [misc]
+dataclasses_final.py:8: error: Final can be only used as an outermost qualifier in a variable annotation  [valid-type]
+dataclasses_final.py:13: error: Expression is of type "Any", not "int"  [assert-type]
+dataclasses_final.py:24: error: Cannot assign to final attribute "final_no_default"  [misc]
+dataclasses_final.py:25: error: Cannot assign to final attribute "final_with_default"  [misc]
+dataclasses_final.py:26: error: Cannot access final instance attribute "final_no_default" on class object  [misc]
+dataclasses_final.py:26: error: Cannot assign to final attribute "final_no_default"  [misc]
+dataclasses_final.py:27: error: Cannot assign to final attribute "final_with_default"  [misc]
+"""

conformance/results/mypy/version.toml

@@ -1,2 +1,2 @@
 version = "mypy 1.10.0"
-test_duration = 1.4
+test_duration = 1.0

conformance/results/pyre/dataclasses_final.toml

@@ -0,0 +1,19 @@
+conformant = "Partial"
+notes = """
+Mis-handles Final nested inside ClassVar.
+"""
+conformance_automated = "Fail"
+errors_diff = """
+Line 8: Unexpected errors ['dataclasses_final.py:8:4 Incompatible attribute type [8]: Attribute `final_classvar` declared in class `D` has type `Final[int]` but is used as type `int`.', 'dataclasses_final.py:8:4 Invalid type [31]: Expression `Final[int]` is not a valid type. Final cannot be nested.']
+Line 13: Unexpected errors ['dataclasses_final.py:13:0 Incompatible parameter type [6]: In call `assert_type`, for 1st positional argument, expected `int` but got `Final[int]`.']
+"""
+output = """
+dataclasses_final.py:8:4 Incompatible attribute type [8]: Attribute `final_classvar` declared in class `D` has type `Final[int]` but is used as type `int`.
+dataclasses_final.py:8:4 Invalid type [31]: Expression `Final[int]` is not a valid type. Final cannot be nested.
+dataclasses_final.py:13:0 Incompatible parameter type [6]: In call `assert_type`, for 1st positional argument, expected `int` but got `Final[int]`.
+dataclasses_final.py:16:0 Incompatible attribute type [8]: Attribute `final_classvar` declared in class `D` has type `Final[int]` but is used as type `int`.
+dataclasses_final.py:24:0 Invalid assignment [41]: Cannot reassign final attribute `d.final_no_default`.
+dataclasses_final.py:25:0 Invalid assignment [41]: Cannot reassign final attribute `d.final_with_default`.
+dataclasses_final.py:26:0 Invalid assignment [41]: Cannot reassign final attribute `D.final_no_default`.
+dataclasses_final.py:27:0 Invalid assignment [41]: Cannot reassign final attribute `D.final_with_default`.
+"""

conformance/results/pyre/version.toml

@@ -1,2 +1,2 @@
 version = "pyre 0.9.21"
-test_duration = 3.2
+test_duration = 1.9

conformance/results/pyright/dataclasses_final.toml

@@ -0,0 +1,29 @@
+conformant = "Partial"
+notes = """
+Doesn't support Final nested inside ClassVar.
+"""
+conformance_automated = "Fail"
+errors_diff = """
+Line 8: Unexpected errors ['dataclasses_final.py:8:30 - error: "Final" is not allowed in this context', 'dataclasses_final.py:8:44 - error: Expression of type "Literal[4]" is incompatible with declared type "Final"']
+Line 13: Unexpected errors ['dataclasses_final.py:13:13 - error: "assert_type" mismatch: expected "int" but received "Final" (reportAssertTypeFailure)']
+"""
+output = """
+dataclasses_final.py:8:30 - error: "Final" is not allowed in this context
+dataclasses_final.py:8:44 - error: Expression of type "Literal[4]" is incompatible with declared type "Final"
+  "Literal[4]" is incompatible with "Final" (reportAssignmentType)
+dataclasses_final.py:13:13 - error: "assert_type" mismatch: expected "int" but received "Final" (reportAssertTypeFailure)
+dataclasses_final.py:16:20 - error: Cannot assign to attribute "final_classvar" for class "type[D]"
+  "Literal[10]" is incompatible with "Final" (reportAttributeAccessIssue)
+dataclasses_final.py:24:3 - error: Cannot assign to attribute "final_no_default" for class "D"
+  "final_no_default" is declared as Final and cannot be reassigned
+    Attribute "__set__" is unknown (reportAttributeAccessIssue)
+dataclasses_final.py:25:3 - error: Cannot assign to attribute "final_with_default" for class "D"
+  "final_with_default" is declared as Final and cannot be reassigned
+    Attribute "__set__" is unknown (reportAttributeAccessIssue)
+dataclasses_final.py:26:3 - error: Cannot assign to attribute "final_no_default" for class "type[D]"
+  "final_no_default" is declared as Final and cannot be reassigned
+    Attribute "__set__" is unknown (reportAttributeAccessIssue)
+dataclasses_final.py:27:3 - error: Cannot assign to attribute "final_with_default" for class "type[D]"
+  "final_with_default" is declared as Final and cannot be reassigned
+    Attribute "__set__" is unknown (reportAttributeAccessIssue)
+"""

conformance/results/pyright/version.toml

@@ -1,2 +1,2 @@
 version = "pyright 1.1.363"
-test_duration = 1.4
+test_duration = 1.7

conformance/results/pytype/dataclasses_final.toml

@@ -0,0 +1,17 @@
+conformant = "Partial"
+notes = """
+Doesn't handle Final nested inside ClassVar.
+"""
+errors_diff = """
+Line 16: Expected 1 errors
+Line 24: Expected 1 errors
+Line 26: Expected 1 errors
+Line 8: Unexpected errors ['File "dataclasses_final.py", line 8, in D: Invalid use of typing.Final [final-error]', 'File "dataclasses_final.py", line 8, in D: Invalid type annotation \\'ClassVar[Final[int]]\\'  [invalid-annotation]']
+"""
+output = """
+File "dataclasses_final.py", line 8, in D: Invalid use of typing.Final [final-error]
+File "dataclasses_final.py", line 8, in D: Invalid type annotation 'ClassVar[Final[int]]'  [invalid-annotation]
+File "dataclasses_final.py", line 25, in <module>: Assigning to attribute final_with_default, which was annotated with Final [final-error]
+File "dataclasses_final.py", line 27, in <module>: Assigning to attribute final_with_default, which was annotated with Final [final-error]
+"""
+conformance_automated = "Fail"

conformance/results/pytype/version.toml

@@ -1,2 +1,2 @@
 version = "pytype 2024.04.11"
-test_duration = 30.6
+test_duration = 28.3

conformance/results/results.html

@@ -159,16 +159,16 @@ <h3>Python Type System Conformance Test Results</h3>
         <div class="table_container"><table><tbody>
 <tr><th class="col1">&nbsp;</th>
 <th class='tc-header'><div class='tc-name'>mypy 1.10.0</div>
-<div class='tc-time'>1.4sec</div>
+<div class='tc-time'>1.0sec</div>
 </th>
 <th class='tc-header'><div class='tc-name'>pyright 1.1.363</div>
-<div class='tc-time'>1.4sec</div>
+<div class='tc-time'>1.7sec</div>
 </th>
 <th class='tc-header'><div class='tc-name'>pyre 0.9.21</div>
-<div class='tc-time'>3.2sec</div>
+<div class='tc-time'>1.9sec</div>
 </th>
 <th class='tc-header'><div class='tc-name'>pytype 2024.04.11</div>
-<div class='tc-time'>30.6sec</div>
+<div class='tc-time'>28.3sec</div>
 </th>
 </tr>
 <tr><th class="column" colspan="5">
@@ -690,6 +690,12 @@ <h3>Python Type System Conformance Test Results</h3>
 <th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Incorrectly generates error when calling constructor of dataclass with descriptor.</p></span></div></th>
 <th class="column col2 not-conformant"><div class="hover-text">Unsupported<span class="tooltip-text" id="bottom"><p>Does not understand descriptor objects in dataclass.</p></span></div></th>
 </tr>
+<tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dataclasses_final</th>
+<th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Wrongly requires a Final dataclass field to be initialized at class level.</p><p>Doesn't support Final nested inside ClassVar.</p></span></div></th>
+<th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Doesn't support Final nested inside ClassVar.</p></span></div></th>
+<th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Mis-handles Final nested inside ClassVar.</p></span></div></th>
+<th class="column col2 partially-conformant"><div class="hover-text">Partial<span class="tooltip-text" id="bottom"><p>Doesn't handle Final nested inside ClassVar.</p></span></div></th>
+</tr>
 <tr><th class="column col1">&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;dataclasses_frozen</th>
 <th class="column col2 conformant">Pass</th>
 <th class="column col2 conformant">Pass</th>

conformance/tests/dataclasses_final.py

@@ -0,0 +1,27 @@
+from dataclasses import dataclass
+from typing import assert_type, ClassVar, Final
+
+@dataclass
+class D:
+    final_no_default: Final[int]
+    final_with_default: Final[str] = "foo"
+    final_classvar: ClassVar[Final[int]] = 4
+    # we don't require support for Final[ClassVar[...]] because the dataclasses
+    # runtime implementation won't recognize it as a ClassVar either
+
+# An explicitly marked ClassVar can be accessed on the class:
+assert_type(D.final_classvar, int)
+
+# ...but not assigned to, because it's Final:
+D.final_classvar = 10  # E: can't assign to final attribute
+
+# A non-ClassVar attribute (with or without default) is a dataclass field:
+d = D(final_no_default=1, final_with_default="bar")
+assert_type(d.final_no_default, int)
+assert_type(d.final_with_default, str)
+
+# ... but can't be assigned to (on the class or on an instance):
+d.final_no_default = 10  # E: can't assign to final attribute
+d.final_with_default = "baz"  # E: can't assign to final attribute
+D.final_no_default  = 10  # E: can't assign to final attribute / can't assign instance attr on class
+D.final_with_default  = "baz"  # E: can't assign to final attribute / can't assign instance attr on class

conformance/tests/qualifiers_final_annotation.py

@@ -98,7 +98,7 @@ class ClassCChild(ClassC):
 
 # > Type checkers should infer a final attribute that is initialized in a class
 # > body as being a class variable. Variables should not be annotated with both
-# > ClassVar and Final.
+# > ClassVar and Final. (Except in a dataclass; see dataclasses_final.py.)
 
 
 class ClassD: