Add tests

__tests__/installer.test.ts

@@ -17,5 +17,58 @@ describe('installer tests', () => {
     await io.rmRF(tempDir);
   });
 
-  it('TODO - Add tests', async () => {});
+  afterAll(async () => {
+    try {
+      await io.rmRF(toolDir);
+      await io.rmRF(tempDir);
+    } catch {
+      console.log('Failed to remove test directories');
+    }
+  }, 100000);
+
+  it('Acquires version of dotnet if no matching version is installed', async () => {
+    await getDotnet('2.2.104');
+    const nodeDir = path.join(toolDir, 'dncs', '2.2.104', os.arch());
+
+    expect(fs.existsSync(`${nodeDir}.complete`)).toBe(true);
+    expect(fs.existsSync(path.join(nodeDir, 'dotnet.exe'))).toBe(true);
+  }, 100000);
+  
+  it('Throws if no location contains correct dotnet version', async () => {
+    let thrown = false;
+    try {
+      await getDotnet('1000.0.0')
+    } catch {
+      thrown = true;
+    }
+    expect(thrown).toBe(true);
   });
+
+  it('Uses version of dotnet installed in cache', async () => {
+    const dotnetDir: string = path.join(toolDir, 'dncs', '250.0.0', os.arch());
+    await io.mkdirP(dotnetDir);
+    fs.writeFileSync(`${dotnetDir}.complete`, 'hello');
+    // This will throw if it doesn't find it in the cache (because no such version exists)
+    await getDotnet('250.0.0');
+    return;
+  });
+
+  it('Doesnt use version of dotnet that was only partially installed in cache', async () => {
+    const dotnetDir: string = path.join(toolDir, 'dncs', '251.0.0', os.arch());
+    await io.mkdirP(dotnetDir);
+    let thrown = false;
+    try {
+      // This will throw if it doesn't find it in the cache (because no such version exists)
+      await getDotnet('251.0.0');
+    } catch {
+      thrown = true;
+    }
+    expect(thrown).toBe(true);
+    return;
+  });
+});
+
+async function getDotnet(version: string): Promise<void> {
+  const dotnetInstaller = new installer.DotnetCoreInstaller(version);
+  await dotnetInstaller.installDotnet();
+}