Skylint: check for bad operations

So far, only checks for usages of '+' on dictionary literals and
comprehensions.

RELNOTES: none
PiperOrigin-RevId: 170336917

2 files changed, 72 insertions, 1 deletions

diff --git a/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/BadOperationCheckerTest.java b/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/BadOperationCheckerTest.java
new file mode 100644
index 0000000000..a9a2a46ff1
--- /dev/null
+++ b/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/BadOperationCheckerTest.java
@@ -0,0 +1,70 @@
+// 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.skylark.skylint;
+
+import com.google.common.truth.Truth;
+import com.google.devtools.build.lib.syntax.BuildFileAST;
+import java.util.List;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+@RunWith(JUnit4.class)
+public class BadOperationCheckerTest {
+  private static List<Issue> findIssues(String... lines) {
+    String content = String.join("\n", lines);
+    BuildFileAST ast =
+        BuildFileAST.parseString(
+            event -> {
+              throw new IllegalArgumentException(event.getMessage());
+            },
+            content);
+    return BadOperationChecker.check(ast);
+  }
+
+  @Test
+  public void dictionaryLiteralPlusOperator() {
+    Truth.assertThat(findIssues("{} + foo").toString())
+        .contains(":1:1: '+' operator is deprecated and should not be used on dictionaries");
+    Truth.assertThat(findIssues("foo + {}").toString())
+        .contains(":1:1: '+' operator is deprecated and should not be used on dictionaries");
+    Truth.assertThat(findIssues("foo += {}").toString())
+        .contains(":1:1: '+' operator is deprecated and should not be used on dictionaries");
+  }
+
+  @Test
+  public void dictionaryComprehensionPlusOperator() {
+    Truth.assertThat(findIssues("{k:v for k,v in []} + foo").toString())
+        .contains(":1:1: '+' operator is deprecated and should not be used on dictionaries");
+    Truth.assertThat(findIssues("foo + {k:v for k,v in []}").toString())
+        .contains(":1:1: '+' operator is deprecated and should not be used on dictionaries");
+    Truth.assertThat(findIssues("foo += {k:v for k,v in []}").toString())
+        .contains(":1:1: '+' operator is deprecated and should not be used on dictionaries");
+  }
+
+  @Test
+  public void dictionaryPlusOperatorNested() {
+    Truth.assertThat(findIssues("foo + ({} + bar)").toString())
+        .contains(":1:7: '+' operator is deprecated and should not be used on dictionaries");
+    Truth.assertThat(findIssues("foo + (bar + {})").toString())
+        .contains(":1:7: '+' operator is deprecated and should not be used on dictionaries");
+  }
+
+  @Test
+  public void plusOperatorNoIssue() {
+    Truth.assertThat(findIssues("foo + bar")).isEmpty();
+    Truth.assertThat(findIssues("foo += bar")).isEmpty();
+  }
+}
diff --git a/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/LinterTest.java b/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/LinterTest.java
index 3bbade4733..98c4bfc8d5 100644
--- a/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/LinterTest.java
+++ b/src/tools/skylark/javatests/com/google/devtools/skylark/skylint/LinterTest.java
@@ -29,7 +29,7 @@ public class LinterTest {
     final String file =
         String.join(
             "\n",
-            "_unusedVar = function()",
+            "_unusedVar = function() + {}",
             "load(':foo.bzl', 'bar')",
             "def function():",
             "  return",
@@ -39,6 +39,7 @@ public class LinterTest {
             .setFileContentsReader(p -> file.getBytes(StandardCharsets.ISO_8859_1))
             .lint(Paths.get("foo"))
             .toString();
+    Truth.assertThat(errorMessages).contains("'+' operator is deprecated"); // bad operation checker
     Truth.assertThat(errorMessages).contains("unreachable statement"); // control flow checker
     Truth.assertThat(errorMessages).contains("has no module docstring"); // docstring checker
     Truth.assertThat(errorMessages)