[TypeScript] 期待した通りのコンパイルエラーが出るかどうかテストするやつ

_runner.ts

/*
 * 1. ../tsconfig.json に設定ファイルを置く
 * 2. ../cases/ の中に example.ts みたいなファイルを置く (/// TSXXXX: ～ でその行で期待するコンパイルを記述する。～の部分は正規表現)
 * 3. _runner.ts を ava で実行すると、出力サンプルみたいな感じで結果が出力される
 */

import * as ts from "typescript/lib/typescript";
import * as fs from "fs";
import * as path from "path";
import * as glob from "glob";
import test from "ava";

interface ExpectedError {
    code: string;
    message?: RegExp;
}
interface ActualError {
    code: string;
    message?: string;
}

const NoError = { code: "<no error>" };

function getExpectedErrors(file: string): ExpectedError[] {
    const lines = fs.readFileSync(file).toString().split(/\r?\n/);
    const ret: ExpectedError[] = [];
    lines.forEach((line, n) => {
        const match = /\/\/\/\s*(TS[0-9]+)\s*:\s*(.*)$/.exec(line);
        if (match) {
            ret[n + 1] = { code: match[1], message: new RegExp(match[2]) };
        }
    });
    return ret;
}

function getFailureMessage(line: number, expected: ExpectedError, actual: ActualError) {
    const expectedString = expected.message ? `${ expected.code }: ${ expected.message }` : expected.code;
    const actualString = actual.message ? `${ actual.code }: ${ actual.message }` : actual.code;

    return (
        `At line ${line}
........ -----------
........ [expected]
........ ${ expectedString.replace(/^/gm, "  ") }
........ [actual]
........ ${ actualString.replace(/^/gm, "  ") }
........ `.replace(/^\.+ /gm, ""));
}

const baseDir = path.dirname(__dirname);
const configPath = path.join(baseDir, "tsconfig.json");

const configContent = fs.readFileSync(configPath).toString();
const parsed = ts.parseJsonConfigFileContent(JSON.parse(configContent), ts.sys, baseDir);

const cases = glob.sync(path.join(baseDir, "cases/*.ts"));
const host: ts.LanguageServiceHost = {
    getScriptFileNames: () => cases,
    getScriptVersion: f => "0",
    getScriptSnapshot: f => {
        if (!fs.existsSync(f)) {
            return undefined;
        }
        return ts.ScriptSnapshot.fromString(fs.readFileSync(f).toString());
    },
    getCurrentDirectory: () => process.cwd(),
    getCompilationSettings: () => parsed.options,
    getDefaultLibFileName: options => ts.getDefaultLibFileName(options)
}

const service = ts.createLanguageService(host, ts.createDocumentRegistry());
cases.forEach(f => {
    const filename = path.basename(f);

    test(filename, t => {
        const expectedErrors = getExpectedErrors(f);
        const output = service.getEmitOutput(f);
        const errors: ActualError[] = [];
        service.getSemanticDiagnostics(f).forEach(d => {
            const { line, character } = d.file.getLineAndCharacterOfPosition(d.start);
            const message = ts.flattenDiagnosticMessageText(d.messageText, "\n");
            errors[line + 1] = { code: `TS${d.code}`, message };
        });
        const msg: string[] = [];
        for (let i = 0; i < expectedErrors.length || i < errors.length; ++i) {
            const expected = expectedErrors[i] || NoError;
            const actual = errors[i] || NoError;
            if (expected.code !== actual.code) {
                msg.push(getFailureMessage(i, expected, actual));
            }
            else if (expected.message && actual.message && !expected.message.test(actual.message)) {
                msg.push(getFailureMessage(i, expected, actual));
            }
        }
        if (msg.length > 0) {
            msg.push(`> ${msg.length} failures are found.`)
            t.fail("\n" + msg.join("\n"));
        }
    });
});

example.ts

interface Foo {
    foo: string;
    bar: number;
}

function testfunc(foo: Foo) {   /// TS9999: unknown error
    console.log(foo.fooo);      /// TS2339: Property 'fooo' does not exist
}

testfunc({ foo: true });        /// TS2345: Property 'bar' is missing in

出力サンプル

  × example.ts
At line 6
-----------
[expected]
  TS9999: /unknown error/
[actual]
  <no error>

At line 10
-----------
[expected]
  TS2345: /Property 'bar' is missing in/
[actual]
  TS2345: Argument of type '{ foo: boolean; }' is not assignable to parameter of type 'Foo'.
    Types of property 'foo' are incompatible.
      Type 'boolean' is not assignable to type 'string'.

> 2 failures are found.

1 test failed [20:24:04]