ProblemMatcher default values improvements

* by default regex group 0 should be used for message. If user has not
  specified the regex group - this means that message does not have one.
  Better to use whole line as default, than define regex group, which
  may not be in the regex.
* in case if line has not been defined, first line can be used to
  identify the problem.

Why are these defaults useful?

As an example I have a **py.test** output

```
tests/test_something.py .F.....................
```

`F` identifies that one of the test failed.

My problemMatcher pattern is very simple

```
"problemMatcher": {
        "owner": "python",
        "fileLocation": ["relative", "${workspaceRoot}"],
        "pattern": {
                "regexp": "([^\\s=]+) \\.*F\\.*",
                "file": 1
        }
}
```

As you can see I cannot define location. I can define message=0 on my
own, but guess that default=0 is better than 4.

src/vs/platform/markers/common/problemMatcher.ts

@@ -257,7 +257,7 @@ class AbstractLineMatcher implements ILineMatcher {
 			return this.parseLocationInfo(data.location);
 		}
 		if (!data.line) {
-			return null;
+			return this.createLocation(1, undefined, undefined, undefined);
 		}
 		let startLine = parseInt(data.line);
 		let startColumn = data.column ? parseInt(data.column) : undefined;
@@ -903,31 +903,28 @@ export class ProblemMatcherParser extends Parser {
 			}
 		});
 		if (setDefaults) {
+			// In case if patternMatcher does not have location and message defined
+			// use first line as location and whole line as a message.
 			if (result.location) {
 				result = Objects.mixin(result, {
 					file: 1,
-					message: 4
+					message: 0
 				}, false);
 			} else {
 				result = Objects.mixin(result, {
 					file: 1,
-					line: 2,
-					column: 3,
-					message: 4
+					message: 0
 				}, false);
 			}
 		}
 		return result;
 	}
 
 	private validateProblemPattern(values: ProblemPattern[]): void {
-		let file: boolean, message: boolean, location: boolean, line: boolean;
+		let file: boolean;
 		let regexp: number = 0;
 		values.forEach(pattern => {
 			file = file || !!pattern.file;
-			message = message || !!pattern.message;
-			location = location || !!pattern.location;
-			line = line || !!pattern.line;
 			if (pattern.regexp) {
 				regexp++;
 			}
@@ -936,9 +933,9 @@ export class ProblemMatcherParser extends Parser {
 			this.status.state = ValidationState.Error;
 			this.log(NLS.localize('ProblemMatcherParser.problemPattern.missingRegExp', 'The problem pattern is missing a regular expression.'));
 		}
-		if (!(file && message && (location || line))) {
+		if (!file) {
 			this.status.state = ValidationState.Error;
-			this.log(NLS.localize('ProblemMatcherParser.problemPattern.missingProperty', 'The problem pattern is invalid. It must have at least a file, message and line or location match group.'));
+			this.log(NLS.localize('ProblemMatcherParser.problemPattern.missingProperty', 'The problem pattern is invalid. It must have at least a file match group.'));
 		}
 	}
 

src/vs/platform/markers/test/common/problemMatcher.test.ts

@@ -0,0 +1,71 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+'use strict';
+
+
+import assert = require('assert');
+
+import * as Types from 'vs/base/common/types';
+
+import Severity from 'vs/base/common/severity';
+import {createLineMatcher, ProblemMatcher, ProblemPattern, ApplyToKind, FileLocationKind} from 'vs/platform/markers/common/problemMatcher';
+
+suite('Problem Matcher', () => {
+	test('default location for single line matcher', () => {
+		let problemMatcher = <ProblemMatcher>{
+			owner: "external",
+			applyTo: ApplyToKind.allDocuments,
+			fileLocation: FileLocationKind.Absolute,
+			pattern: <ProblemPattern>{
+				regexp: /([a-z]+) abc/,
+				file: 1,
+				message: 0
+			}
+		};
+		var lineMatcher = createLineMatcher(problemMatcher);
+		var result = lineMatcher.handle(["filename abc"]);
+		assert.ok(result.match);
+		assert.ok(!result.continue);
+		assert.ok(Types.isUndefined(result.match.marker.code));
+		assert.equal(result.match.marker.severity, Severity.Error);
+		assert.equal(result.match.marker.message, "filename abc");
+		assert.ok(Types.isUndefined(result.match.marker.source));
+		assert.equal(result.match.marker.startLineNumber, 1);
+		assert.equal(result.match.marker.startColumn, 1);
+		assert.equal(result.match.marker.endLineNumber, 1);
+		assert.equal(result.match.marker.endColumn, Number.MAX_VALUE);
+	});
+
+	test('default location for multi line matcher', () => {
+		let problemMatcher = <ProblemMatcher>{
+			owner: "external",
+			applyTo: ApplyToKind.allDocuments,
+			fileLocation: FileLocationKind.Absolute,
+			pattern: [
+				<ProblemPattern>{
+					regexp: /file = ([a-z]+)/,
+					file: 1,
+					message: 0
+				},
+				<ProblemPattern>{
+					regexp: /severity = ([a-z]+)/,
+					severity: 1
+				}
+			]
+		};
+		var lineMatcher = createLineMatcher(problemMatcher);
+		var result = lineMatcher.handle(["file = filename", "severity = warning"]);
+		assert.ok(result.match);
+		assert.ok(!result.continue);
+		assert.ok(Types.isUndefined(result.match.marker.code));
+		assert.equal(result.match.marker.severity, Severity.Warning);
+		assert.equal(result.match.marker.message, "file = filename");
+		assert.ok(Types.isUndefined(result.match.marker.source));
+		assert.equal(result.match.marker.startLineNumber, 1);
+		assert.equal(result.match.marker.startColumn, 1);
+		assert.equal(result.match.marker.endLineNumber, 1);
+		assert.equal(result.match.marker.endColumn, Number.MAX_VALUE);
+	})
+});

src/vs/workbench/parts/tasks/test/node/configuration.test.ts

@@ -171,9 +171,7 @@ class PatternBuilder {
 		this.result = {
 			regexp: regExp,
 			file: 1,
-			message: 4,
-			line: 2,
-			column : 3
+			message: 0
 		}
 	}