Split off SkylarkSemanticsOptions into an immutable class
This is a first step toward making the core Skylark interpreter (the syntax/ directory) not depend on the options parser. Subsequent CLs will replace uses of SkylarkSemanticsOptions within the interpreter with uses of SkylarkSemantics, and move SkylarkSemanticsOptions to the packages/ directory alongside SkylarkSemanticsCodec.
SkylarkSemantics will also replace SkylarkSemanticsOptions as the value that gets passed through Skyframe. This is nice because SkylarkSemantics is strictly immutable, whereas options classes are only kinda-sorta-immutable.
The downside is significantly more redundancy when defining new options. But some of the work is saved by using AutoValue, and there are tests that protect us from dumb mechanical errors. The details are outlined in the javadoc for SkylarkSemanticsOptions and SkylarkSemanticsConsistencyTest.
RELNOTES: None
PiperOrigin-RevId: 171060034
diff --git a/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java b/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
new file mode 100644
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--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/packages/SkylarkSemanticsConsistencyTest.java
@@ -0,0 +1,160 @@
+// Copyright 2017 The Bazel Authors. 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.google.devtools.build.lib.packages;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import com.google.devtools.build.lib.skyframe.serialization.testutils.TestUtils;
+import com.google.devtools.build.lib.syntax.SkylarkSemantics;
+import com.google.devtools.build.lib.syntax.SkylarkSemanticsOptions;
+import com.google.devtools.common.options.Options;
+import com.google.devtools.common.options.OptionsParser;
+import java.util.Arrays;
+import java.util.Random;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/**
+ * Tests for the flow of flags from {@link SkylarkSemanticsOptions} to {@link SkylarkSemantics}, and
+ * to and from {@code SkylarkSemantics}' serialized representation.
+ *
+ * <p>When adding a new option, it is trivial to make a transposition error or a copy/paste error.
+ * These tests guard against such errors. The following possible bugs are considered:
+ * <ul>
+ * <li>If a new option is added to {@code SkylarkSemantics} but not to {@code
+ * SkylarkSemanticsOptions}, or vice versa, then the programmer will either be unable to
+ * implement its behavior, or unable to test it from the command line and add user
+ * documentation. We hope that the programmer notices this on their own.
+ *
+ * <li>If {@link SkylarkSemanticsOptions#toSkylarkSemantics} or {@link
+ * SkylarkSemanticsCodec#deserialize} is not updated to set all fields of {@code
+ * SkylarkSemantics}, then it will fail immediately because all fields of {@link
+ * SkylarkSemantics.Builder} are mandatory.
+ *
+ * <li>To catch a copy/paste error where the wrong field's data is threaded through {@code
+ * toSkylarkSemantics()} or {@code deserialize(...)}, we repeatedly generate matching random
+ * instances of the input and expected output objects.
+ *
+ * <li>The {@link #checkDefaultsMatch} test ensures that there is no divergence between the
+ * default values of the two classes.
+ *
+ * <li>There is no test coverage for failing to update the non-generated webpage documentation.
+ * So don't forget that!
+ * </ul>
+ */
+@RunWith(JUnit4.class)
+public class SkylarkSemanticsConsistencyTest {
+
+ private static final int NUM_RANDOM_TRIALS = 10;
+
+ /**
+ * Checks that a randomly generated {@link SkylarkSemanticsOptions} object can be converted to a
+ * {@link SkylarkSemantics} object with the same field values.
+ */
+ @Test
+ public void optionsToSemantics() throws Exception {
+ for (int i = 0; i < NUM_RANDOM_TRIALS; i++) {
+ long seed = i;
+ SkylarkSemanticsOptions options = buildRandomOptions(new Random(seed));
+ SkylarkSemantics semantics = buildRandomSemantics(new Random(seed));
+ SkylarkSemantics semanticsFromOptions = options.toSkylarkSemantics();
+ assertThat(semanticsFromOptions).isEqualTo(semantics);
+ }
+ }
+
+ /*
+ * Checks that a randomly generated {@link SkylarkSemantics} object can be serialized and
+ * deserialized to an equivalent object.
+ */
+ @Test
+ public void serializationRoundTrip() throws Exception {
+ SkylarkSemanticsCodec codec = new SkylarkSemanticsCodec();
+ for (int i = 0; i < NUM_RANDOM_TRIALS; i++) {
+ SkylarkSemantics semantics = buildRandomSemantics(new Random(i));
+ SkylarkSemantics deserialized =
+ TestUtils.fromBytes(codec, TestUtils.toBytes(codec, semantics));
+ assertThat(deserialized).isEqualTo(semantics);
+ }
+ }
+
+ @Test
+ public void checkDefaultsMatch() {
+ SkylarkSemanticsOptions defaultOptions = Options.getDefaults(SkylarkSemanticsOptions.class);
+ SkylarkSemantics defaultSemantics = SkylarkSemantics.DEFAULT_SEMANTICS;
+ SkylarkSemantics semanticsFromOptions = defaultOptions.toSkylarkSemantics();
+ assertThat(semanticsFromOptions).isEqualTo(defaultSemantics);
+ }
+
+ /**
+ * Constructs a {@link SkylarkSemanticsOptions} object with random fields. Must access {@code
+ * rand} using the same sequence of operations (for the same fields) as {@link
+ * #buildRandomSemantics}.
+ */
+ private static SkylarkSemanticsOptions buildRandomOptions(Random rand) throws Exception {
+ return parseOptions(
+ // <== Add new options here in alphabetic order ==>
+ "--incompatible_bzl_disallow_load_after_statement=" + rand.nextBoolean(),
+ "--incompatible_checked_arithmetic=" + rand.nextBoolean(),
+ "--incompatible_comprehension_variables_do_not_leak=" + rand.nextBoolean(),
+ "--incompatible_depset_is_not_iterable=" + rand.nextBoolean(),
+ "--incompatible_descriptive_string_representations=" + rand.nextBoolean(),
+ "--incompatible_dict_literal_has_no_duplicates=" + rand.nextBoolean(),
+ "--incompatible_disallow_dict_plus=" + rand.nextBoolean(),
+ "--incompatible_disallow_keyword_only_args=" + rand.nextBoolean(),
+ "--incompatible_disallow_set_constructor=" + rand.nextBoolean(),
+ "--incompatible_disallow_toplevel_if_statement=" + rand.nextBoolean(),
+ "--incompatible_list_plus_equals_inplace=" + rand.nextBoolean(),
+ "--incompatible_load_argument_is_label=" + rand.nextBoolean(),
+ "--incompatible_new_actions_api=" + rand.nextBoolean(),
+ "--incompatible_string_is_not_iterable=" + rand.nextBoolean(),
+ "--internal_do_not_export_builtins=" + rand.nextBoolean(),
+ "--internal_skylark_flag_test_canary=" + rand.nextBoolean()
+ );
+ }
+
+ /**
+ * Constructs a {@link SkylarkSemantics} object with random fields. Must access {@code rand} using
+ * the same sequence of operations (for the same fields) as {@link #buildRandomOptions}.
+ */
+ private static SkylarkSemantics buildRandomSemantics(Random rand) {
+ return SkylarkSemantics.builder()
+ // <== Add new options here in alphabetic order ==>
+ .incompatibleBzlDisallowLoadAfterStatement(rand.nextBoolean())
+ .incompatibleCheckedArithmetic(rand.nextBoolean())
+ .incompatibleComprehensionVariablesDoNotLeak(rand.nextBoolean())
+ .incompatibleDepsetIsNotIterable(rand.nextBoolean())
+ .incompatibleDescriptiveStringRepresentations(rand.nextBoolean())
+ .incompatibleDictLiteralHasNoDuplicates(rand.nextBoolean())
+ .incompatibleDisallowDictPlus(rand.nextBoolean())
+ .incompatibleDisallowKeywordOnlyArgs(rand.nextBoolean())
+ .incompatibleDisallowSetConstructor(rand.nextBoolean())
+ .incompatibleDisallowToplevelIfStatement(rand.nextBoolean())
+ .incompatibleListPlusEqualsInplace(rand.nextBoolean())
+ .incompatibleLoadArgumentIsLabel(rand.nextBoolean())
+ .incompatibleNewActionsApi(rand.nextBoolean())
+ .incompatibleStringIsNotIterable(rand.nextBoolean())
+ .internalDoNotExportBuiltins(rand.nextBoolean())
+ .internalSkylarkFlagTestCanary(rand.nextBoolean())
+ .build();
+ }
+
+ private static SkylarkSemanticsOptions parseOptions(String... args) throws Exception {
+ OptionsParser parser = OptionsParser.newOptionsParser(SkylarkSemanticsOptions.class);
+ parser.setAllowResidue(false);
+ parser.parse(Arrays.asList(args));
+ return parser.getOptions(SkylarkSemanticsOptions.class);
+ }
+}
