Avoid trying to save descriptors to cache when their computation failed (#1304)

Author: guillaume-dequenne

python-frontend/src/main/java/org/sonar/python/semantic/ProjectLevelSymbolTable.java

@@ -169,6 +169,7 @@ public void insertEntry(String moduleName, Set<Descriptor> descriptors) {
     this.globalDescriptorsByModuleName.put(moduleName, descriptors);
   }
 
+  @CheckForNull
   public Set<Descriptor> descriptorsForModule(String moduleName) {
     return globalDescriptorsByModuleName.get(moduleName);
   }

sonar-python-plugin/src/main/java/org/sonar/plugins/python/indexer/SonarQubePythonIndexer.java

@@ -154,8 +154,13 @@ private void saveGlobalSymbolsInCache(List<InputFile> files) {
     for (InputFile inputFile : files) {
       String moduleFQN = inputFileToFQN.get(inputFile);
       Set<Descriptor> descriptors = projectLevelSymbolTable().descriptorsForModule(moduleFQN);
-      caching.writeProjectLevelSymbolTableEntry(inputFile.key(), descriptors);
-      caching.writeImportsMapEntry(inputFile.key(), projectLevelSymbolTable().importsByModule().get(moduleFQN));
+      Set<String> imports = projectLevelSymbolTable().importsByModule().get(moduleFQN);
+      if (descriptors != null && imports != null) {
+        // Descriptors/imports map may be null if the file failed to parse.
+        // We don't try to save information in the cache in that case.
+        caching.writeProjectLevelSymbolTableEntry(inputFile.key(), descriptors);
+        caching.writeImportsMapEntry(inputFile.key(), imports);
+      }
     }
   }
 

sonar-python-plugin/src/test/java/org/sonar/plugins/python/indexer/SonarQubePythonIndexerTest.java

@@ -326,6 +326,17 @@ public void test_regular_scan_when_scan_without_parsing_fails() {
     assertThat(logTester.logs(LoggerLevel.INFO)).contains("1/1 source file has been analyzed");
   }
 
+  @Test
+  public void test_no_data_in_cache_for_parse_error() {
+    file1 = createInputFile(baseDir, "parse_error.py", InputFile.Status.ADDED, InputFile.Type.MAIN);
+
+    List<InputFile> inputFiles = new ArrayList<>(List.of(file1));
+
+    pythonIndexer = new SonarQubePythonIndexer(inputFiles, cacheContext);
+    pythonIndexer.buildOnce(context);
+    assertThat(writeCache.getData().containsKey(projectSymbolTableCacheKey("moduleKey:parse_error.py"))).isFalse();
+  }
+
   private byte[] importsAsByteArray(List<String> mod) {
     return String.join(";", mod).getBytes(StandardCharsets.UTF_8);
   }

sonar-python-plugin/src/test/resources/org/sonar/plugins/python/indexer/parse_error.py

@@ -0,0 +1 @@
+Hello! I'm a parse error!