Added an optional TSLintErrorSeverity flag (#45)

* Added an optional `TSLintErrorSeverity` flag

Optional MSBuild error severity override, as `"error"` or `"warning"`.

Fixes #19.

* Fixed README.md ordering for error severity

* Moved the "X errors found" message above errors

Now that error printing is a source of errors (albeit very unlikely) it
makes sense to have the summary first.

README.md

@@ -20,6 +20,7 @@ The following properties may be overidden via your targets:
 * **TSLintBreakBuildOnError** -  Whether linting failures should break the build. Defaults to `false`.
 * **TSLintConfig** - Path to a specific tslint.json. Defaults to blank, for any tslint.json on the path.
 * **TSLintDeleteFileListFile** - Whether to delete the file list file when done. Defaults to `true`.
+* **TSLintErrorSeverity** - Optional MSBuild error severity override, as `"error"` or `"warning"`.
 * **TSLintExclude** - Blob of matching file names to exclude. Defaults to none.
 * **TSLintFilesRootDir** - Root directory to work within. Defaults to `$(MSBuildProjectDirectory)`.
 * **TSLintFileListDir** - Directory to put the file list in. Defaults to `$(IntermediateOutDir)`.

src/ArgumentsCollection.ts

@@ -7,6 +7,11 @@ interface ICollected {
      */
     "--config"?: string;
 
+    /**
+     * Override for MSBuild error severity level.
+     */
+    "--error-severity"?: "error" | "warning";
+
     /**
      * A glob path to exclude from linting.
      */
@@ -36,7 +41,7 @@ export class ArgumentsCollection {
      * Whitelist of allowed keys from the .targets file.
      */
     private static allowedKeys: Set<string> = new Set<string>([
-        "--config", "--exclude", "--file-list-file", "--files-root-dir", "--rules-directory"
+        "--config", "--error-severity", "--exclude", "--file-list-file", "--files-root-dir", "--rules-directory"
     ]);
 
     /**
@@ -92,6 +97,13 @@ export class ArgumentsCollection {
         return this.collected["--config"];
     }
 
+    /**
+     * @returns The override for MSBuild error severity level.
+     */
+    public getErrorSeverity(): "error" | "warning" {
+        return this.collected["--error-severity"];
+    }
+
     /**
      * @returns The root directory to work within.
      */

src/ErrorsPrinter.ts

@@ -0,0 +1,110 @@
+/**
+ * MSBuild error printers, keyed by severity level.
+ */
+interface IErrorPrinters {
+    [i: string]: IErrorPrinter;
+}
+
+/**
+ * Prints a single pre-formatted MSBuild error.
+ * 
+ * @param error   A pre-formatted MSBuild error.
+ */
+interface IErrorPrinter {
+    (error: string): void;
+}
+
+/**
+ * Prints MSBuild errors from the TSLint CLI with a severity level.
+ */
+export class ErrorsPrinter {
+    /**
+     * MSBuild error printers, keyed by severity level.
+     */
+    private errorPrinters: IErrorPrinters = {
+        error: (error: string): void => console.error(error),
+        warning: (error: string): void => console.warn(error)
+    };
+
+    /**
+     * Overridden severity level for errors, if provided.
+     */
+    private severityOverride: string;
+
+    /**
+     * Initializes a new instance of the ErrorsPrinter class.
+     * 
+     * @param severityOverride   Overridden severity level for errors, if provided.
+     */
+    public constructor(severityOverride?: string) {
+        this.severityOverride = severityOverride;
+    }
+
+    /**
+     * Prints MSBuild errors.
+     * 
+     * @param errors   MSBuild errors.
+     */
+    public print(errors: string[]): void {
+        for (const error of errors) {
+            this.printError(error);
+        }
+    }
+
+    /**
+     * Prints an MSBuild error.
+     * 
+     * @param error   An MSBuild error.
+     */
+    public printError(error: string): void {
+        const errorSeverity = this.getSeverityFromError(error);
+
+        if (this.severityOverride && this.severityOverride !== errorSeverity) {
+            error = this.replaceErrorSeverity(error, errorSeverity, this.severityOverride);
+        }
+
+        const severity = this.severityOverride || errorSeverity;
+        const printer = this.errorPrinters[severity];
+
+        if (!printer) {
+            throw new Error(`Unknown error severity: '${severity}'.`);
+        }
+
+        printer(error);
+    }
+
+    /**
+     * @param error   An MSBuild error.
+     * @returns The error's severity.
+     */
+    private getSeverityFromError(error: string): string {
+        return error
+            .match(/\):\s.+:/)
+            [0]
+            .replace(/\W/g, "");
+    }
+
+    /**
+     * Replaces an error's severity with a new severity.
+     * 
+     * @param error   An MSBuild error.
+     * @param originalSeverity   The current severity level of the error.
+     * @param newSeverity   A new severity level for the error.
+     * @returns A copy of the error with thenew severity level.
+     */
+    private replaceErrorSeverity(error: string, originalSeverity: string, newSeverity: string): string {
+        return error.replace(
+            this.wrapErrorFormat(originalSeverity),
+            this.wrapErrorFormat(newSeverity));
+    }
+
+    /**
+     * Wraps a severity string with find-and-replace safe markers.
+     * 
+     * @param severity   A severity level.
+     * @returns The severity with find-and-replace safe markers.
+     */
+    private wrapErrorFormat(severity: string): string {
+        return `): ${severity}`;
+    }
+}

src/LintRunner.ts

@@ -40,7 +40,7 @@ export class LintRunner {
      * 
      * @returns A promise for TSLint errors, in alphabetical order of file path.
      */
-    public runTSLint(): Promise<string> {
+    public runTSLint(): Promise<string[]> {
         const linter: ChildProcess = this.runSpawn(
             "node",
             [
@@ -50,11 +50,16 @@ export class LintRunner {
                 "msbuild",
                 ...this.filePaths
             ]);
-        let errors: string = "";
+        let errors: string[] = [];
 
-        return new Promise((resolve: (errors: string) => void, reject: (error: string) => void): void => {
+        return new Promise((resolve: (errors: string[]) => void, reject: (error: string) => void): void => {
             linter.stdout.on("data", (data: Buffer): void => {
-                errors += data.toString();
+                errors.push(
+                    ...data
+                        .toString()
+                        .replace(/\r/g, "")
+                        .split(/\n/g)
+                        .filter((error: string): boolean => !!error));
             });
 
             linter.stderr.on("data", (data: Buffer): void => {

src/TSLint.MSBuild.targets

@@ -13,6 +13,7 @@
       <TSLintBreakBuildOnError Condition="'$(TSLintBreakBuildOnError)' == ''">false</TSLintBreakBuildOnError>
       <TSLintConfig Condition="'$(TSLintConfig)' == ''"></TSLintConfig>
       <TSLintDeleteFileListFile Condition="'$(TSLintDeleteFileListFile)' == ''">true</TSLintDeleteFileListFile>
+      <TSLintErrorSeverity Condition="'$(TSLintErrorSeverity)' == ''"></TSLintErrorSeverity>
       <TSLintExclude Condition="'$(TSLintExclude)' == ''"></TSLintExclude>
       <TSLintFilesRootDir Condition="'$(TSLintFilesRootDir)' == ''">$(MSBuildProjectDirectory)</TSLintFilesRootDir>
       <TSLintFileListDir Condition="'$(TSLintFileListDir)' == ''">$(IntermediateOutDir)</TSLintFileListDir>
@@ -36,7 +37,7 @@
 
     <!-- Run TSLint via the runner -->
     <Exec 
-      Command="&quot;$(TSLintNodeExe)&quot; --harmony --harmony_modules &quot;$(TSLintRunnerScript)&quot; --config &quot;$(TSLintConfig)&quot; --exclude &quot;$(TSLintExclude)&quot; --file-list-file &quot;$(TSLintFileListFile)&quot; --files-root-dir &quot;$(TSLintFilesRootDir)&quot; --rules-directory &quot;$(TSLintRulesDirectory)&quot;"
+      Command="&quot;$(TSLintNodeExe)&quot; --harmony --harmony_modules &quot;$(TSLintRunnerScript)&quot; --config &quot;$(TSLintConfig)&quot; --error-severity &quot;$(TSLintErrorSeverity)&quot; --exclude &quot;$(TSLintExclude)&quot; --file-list-file &quot;$(TSLintFileListFile)&quot; --files-root-dir &quot;$(TSLintFilesRootDir)&quot; --rules-directory &quot;$(TSLintRulesDirectory)&quot;"
       IgnoreExitCode="true">
       <Output TaskParameter="ExitCode" PropertyName="ErrorCode" />
     </Exec>

src/index.ts

@@ -5,6 +5,7 @@ console.log("Starting TSLint runner.");
 import * as fs from "fs";
 import * as path from "path";
 import { ArgumentsCollection } from "./ArgumentsCollection";
+import { ErrorsPrinter } from "./ErrorsPrinter";
 import { LintRunner } from "./LintRunner";
 
 /**
@@ -33,14 +34,9 @@ function getInputFilesList(filePath): string[] {
     console.log(`Running TSLint on ${filePaths.length} file(s).`);
 
     runner.runTSLint()
-        .then(lintErrors => {
-            const numErrors = lintErrors.match(/\n/g).length;
-
-            if (numErrors !== 0) {
-                console.error(lintErrors);
-            }
-
-            console.log(`${numErrors} error(s) found in ${filePaths.length} file(s).`);
+        .then((lintErrors: string[]): void => {
+            console.log(`${lintErrors.length} error(s) found in ${filePaths.length} file(s).`);
+            new ErrorsPrinter(argumentsCollection.getErrorSeverity()).print(lintErrors);
         })
         .catch(error => {
             console.error("Error running TSLint!");

tsconfig.json

@@ -8,6 +8,7 @@
     },
     "files": [
         "src/ArgumentsCollection.ts",
+        "src/ErrorsPrinter.ts",
         "src/index.ts",
         "src/LintRunner.ts",
         "src/TSLintSearcher.ts"