Add installer

* start

* Add tests

* Clean up changes

* Update tool-cache we consume

* Use custom 7zr

__tests__/installer.test.ts

@@ -0,0 +1,96 @@
+import io = require('@actions/io');
+import fs = require('fs');
+import os = require('os');
+import path = require('path');
+
+const toolDir = path.join(__dirname, 'runner', 'tools');
+const tempDir = path.join(__dirname, 'runner', 'temp');
+
+process.env['RUNNER_TOOLSDIRECTORY'] = toolDir;
+process.env['RUNNER_TEMPDIRECTORY'] = tempDir;
+import * as installer from '../src/installer';
+
+describe('installer tests', () => {
+  beforeAll(() => {});
+  beforeAll(async () => {
+    await io.rmRF(toolDir);
+    await io.rmRF(tempDir);
+  });
+
+  it('Acquires version of node if no matching version is installed', async () => {
+    await installer.getNode('10.16.0');
+    const nodeDir = path.join(toolDir, 'node', '10.16.0', os.arch());
+
+    expect(fs.existsSync(`${nodeDir}.complete`)).toBe(true);
+    expect(fs.existsSync(path.join(nodeDir, 'node.exe'))).toBe(true);
+  }, 100000);
+
+  if (process.platform === 'win32') {
+    it('Falls back to backup location if first one doesnt contain correct version', async () => {
+      await installer.getNode('5.10.1');
+      const nodeDir = path.join(toolDir, 'node', '5.10.1', os.arch());
+
+      expect(fs.existsSync(`${nodeDir}.complete`)).toBe(true);
+      expect(fs.existsSync(path.join(nodeDir, 'node.exe'))).toBe(true);
+    }, 100000);
+
+    it('Falls back to third location if second one doesnt contain correct version', async () => {
+      await installer.getNode('0.12.18');
+      const nodeDir = path.join(toolDir, 'node', '0.12.18', os.arch());
+
+      expect(fs.existsSync(`${nodeDir}.complete`)).toBe(true);
+      expect(fs.existsSync(path.join(nodeDir, 'node.exe'))).toBe(true);
+    }, 100000);
+  }
+
+  it('Throws if no location contains correct node version', async () => {
+    let thrown = false;
+    try {
+      await installer.getNode('1000');
+    } catch {
+      thrown = true;
+    }
+    expect(thrown).toBe(true);
+  });
+
+  it('Acquires version of node with long paths', async () => {
+    const toolpath = await installer.getNode('8.8.1');
+    const nodeDir = path.join(toolDir, 'node', '8.8.1', os.arch());
+
+    expect(fs.existsSync(`${nodeDir}.complete`)).toBe(true);
+    expect(fs.existsSync(path.join(nodeDir, 'node.exe'))).toBe(true);
+  }, 100000);
+
+  it('Uses version of node installed in cache', async () => {
+    const nodeDir: string = path.join(toolDir, 'node', '250.0.0', os.arch());
+    await io.mkdirP(nodeDir);
+    fs.writeFileSync(`${nodeDir}.complete`, 'hello');
+    // This will throw if it doesn't find it in the cache (because no such version exists)
+    await installer.getNode('250.0.0');
+    return;
+  });
+
+  it('Doesnt use version of node that was only partially installed in cache', async () => {
+    const nodeDir: string = path.join(toolDir, 'node', '250.0.0', os.arch());
+    await io.mkdirP(nodeDir);
+    let thrown = false;
+    try {
+      // This will throw if it doesn't find it in the cache (because no such version exists)
+      await installer.getNode('251.0.0');
+    } catch {
+      thrown = true;
+    }
+    expect(thrown).toBe(true);
+    return;
+  });
+
+  it('Resolves semantic versions of node installed in cache', async () => {
+    const nodeDir: string = path.join(toolDir, 'node', '250.0.0', os.arch());
+    await io.mkdirP(nodeDir);
+    fs.writeFileSync(`${nodeDir}.complete`, 'hello');
+    // These will throw if it doesn't find it in the cache (because no such version exists)
+    await installer.getNode('250.0.0');
+    await installer.getNode('250');
+    await installer.getNode('250.0');
+  });
+});