Change message parsing in BaseLinter so it respects python.linting.ma…

…xNumberOfProblems (#2208)

news/2 Fixes/2198.md

@@ -0,0 +1,2 @@
+Change linter message parsing so it respects `python.linting.maxNumberOfProblems`.
+(thanks [Scott Saponas](https://github.com/saponas/))

src/client/linters/baseLinter.ts

@@ -149,21 +149,21 @@ export abstract class BaseLinter implements ILinter {
     }
 
     private parseLines(outputLines: string[], regEx: string): ILintMessage[] {
-        return outputLines
-            .filter((value, index) => index <= this.pythonSettings.linting.maxNumberOfProblems)
-            .map(line => {
-                try {
-                    const msg = this.parseLine(line, regEx);
-                    if (msg) {
-                        return msg;
+        const messages: ILintMessage[] = [];
+        for (const line of outputLines) {
+            try {
+                const msg = this.parseLine(line, regEx);
+                if (msg) {
+                    messages.push(msg);
+                    if (messages.length >= this.pythonSettings.linting.maxNumberOfProblems) {
+                        break;
                     }
-                } catch (ex) {
-                    this.logger.logError(`Linter '${this.info.id}' failed to parse the line '${line}.`, ex);
                 }
-                return;
-            })
-            .filter(item => item !== undefined)
-            .map(item => item!);
+            } catch (ex) {
+                this.logger.logError(`Linter '${this.info.id}' failed to parse the line '${line}.`, ex);
+            }
+        }
+        return messages;
     }
 
     private displayLinterResultHeader(data: string) {

src/test/linters/lint.test.ts

@@ -23,6 +23,7 @@ const pep8ConfigPath = path.join(pythoFilesPath, 'pep8config');
 const pydocstyleConfigPath27 = path.join(pythoFilesPath, 'pydocstyleconfig27');
 const pylintConfigPath = path.join(pythoFilesPath, 'pylintconfig');
 const fileToLint = path.join(pythoFilesPath, 'file.py');
+const threeLineLintsPath = path.join(pythoFilesPath, 'threeLineLints.py');
 
 const pylintMessagesToBeReturned: ILintMessage[] = [
     { line: 24, column: 0, severity: LintMessageSeverity.Information, code: 'I0011', message: 'Locally disabling no-member (E1101)', provider: '', type: '' },
@@ -279,4 +280,22 @@ suite('Linting - General Tests', () => {
         assert.notEqual(messages!.filter(x => x.source === 'pylint').length, 0, 'No pylint messages.');
         assert.notEqual(messages!.filter(x => x.source === 'flake8').length, 0, 'No flake8 messages.');
     });
+    // tslint:disable-next-line:no-any
+    async function testLinterMessageCount(product: Product, pythonFile: string, messageCountToBeReceived: number): Promise<any> {
+        const outputChannel = ioc.serviceContainer.get<MockOutputChannel>(IOutputChannel, STANDARD_OUTPUT_CHANNEL);
+        const cancelToken = new CancellationTokenSource();
+        const document = await workspace.openTextDocument(pythonFile);
+
+        await linterManager.setActiveLintersAsync([product], document.uri);
+        const linter = linterManager.createLinter(product, outputChannel, ioc.serviceContainer);
+
+        const messages = await linter.lint(document, cancelToken.token);
+        assert.equal(messages.length, messageCountToBeReceived, 'Expected number of lint errors does not match lint error count');
+    }
+    test('Three line output counted as one message', async () => {
+        const maxErrors = 5;
+        const target = IS_MULTI_ROOT_TEST ? ConfigurationTarget.WorkspaceFolder : ConfigurationTarget.Workspace;
+        await configService.updateSettingAsync('linting.maxNumberOfProblems', maxErrors, rootWorkspaceUri, target);
+        await testLinterMessageCount(Product.pylint, threeLineLintsPath, maxErrors);
+    });
 });

src/test/pythonFiles/linting/threeLineLints.py

@@ -0,0 +1,24 @@
+"""pylint messages with three lines of output"""
+
+__revision__ = None
+
+class Foo(object):
+
+    def __init__(self):
+        pass
+
+    def meth1(self,arg):
+        """missing a space between 'self' and 'arg'. This should trigger the
+        following three line lint warning::
+
+          C: 10, 0: Exactly one space required after comma
+              def meth1(self,arg):
+                             ^ (bad-whitespace)
+
+        The following three lines of tuples should also cause three-line lint
+        errors due to "Exactly one space required after comma" messages.
+        """
+        a = (1,2)
+        b = (1,2)
+        c = (1,2)
+        print (self)