diff --git a/config/__tests__/CLIConfiguration.ts b/config/__tests__/CLIConfiguration.ts
index 54f8d957..d41d53ca 100644
--- a/config/__tests__/CLIConfiguration.ts
+++ b/config/__tests__/CLIConfiguration.ts
@@ -1,13 +1,130 @@
+import { ENVIRONMENTS } from '../../constants/environments';
 import config from '../CLIConfiguration';
 
-// TODO write tests for CLIConfiguration.ts
 describe('config/CLIConfiguration', () => {
+  afterAll(() => {
+    config.setActive(false);
+  });
+
   describe('constructor()', () => {
     it('initializes correctly', () => {
       expect(config).toBeDefined();
       expect(config.options).toBeDefined();
       expect(config.useEnvConfig).toBe(false);
       expect(config.config).toBe(null);
+      expect(config.active).toBe(false);
+    });
+  });
+
+  describe('isActive()', () => {
+    it('returns true when the class is being used', () => {
+      expect(config.isActive()).toBe(false);
+      config.setActive(true);
+      expect(config.isActive()).toBe(true);
+    });
+  });
+
+  describe('getAccount()', () => {
+    it('returns null when no config is loaded', () => {
+      expect(config.getAccount('account-name')).toBe(null);
+    });
+  });
+
+  describe('isConfigFlagEnabled()', () => {
+    it('returns default value when no config is loaded', () => {
+      expect(config.isConfigFlagEnabled('allowUsageTracking', false)).toBe(
+        false
+      );
+    });
+  });
+
+  describe('getAccountId()', () => {
+    it('returns null when it cannot find the account in the config', () => {
+      expect(config.getAccountId('account-name')).toBe(null);
+    });
+  });
+
+  describe('getDefaultAccount()', () => {
+    it('returns null when no config is loaded', () => {
+      expect(config.getDefaultAccount()).toBe(null);
+    });
+  });
+
+  describe('getConfigAccountIndex()', () => {
+    it('returns -1 when no config is loaded', () => {
+      expect(config.getConfigAccountIndex(123)).toBe(-1);
+    });
+  });
+
+  describe('isAccountInConfig()', () => {
+    it('returns false when no config is loaded', () => {
+      expect(config.isAccountInConfig(123)).toBe(false);
+    });
+  });
+
+  describe('getConfigForAccount()', () => {
+    it('returns null when no config is loaded', () => {
+      expect(config.getConfigForAccount(123)).toBe(null);
+    });
+  });
+
+  describe('getEnv()', () => {
+    it('returns PROD when no config is loaded', () => {
+      expect(config.getEnv(123)).toBe(ENVIRONMENTS.PROD);
+    });
+  });
+
+  describe('updateDefaultAccount()', () => {
+    it('throws when no config is loaded', () => {
+      expect(() => {
+        config.updateDefaultAccount('account-name');
+      }).toThrow();
+    });
+  });
+
+  describe('renameAccount()', () => {
+    it('throws when no config is loaded', () => {
+      expect(() => {
+        config.renameAccount('account-name', 'new-account-name');
+      }).toThrow();
+    });
+  });
+
+  describe('removeAccountFromConfig()', () => {
+    it('throws when no config is loaded', () => {
+      expect(() => {
+        config.removeAccountFromConfig('account-name');
+      }).toThrow();
+    });
+  });
+
+  describe('updateDefaultMode()', () => {
+    it('throws when no config is loaded', () => {
+      expect(() => {
+        config.updateDefaultMode('newMode');
+      }).toThrow();
+    });
+  });
+
+  describe('updateHttpTimeout()', () => {
+    it('throws when no config is loaded', () => {
+      expect(() => {
+        config.updateHttpTimeout('1000');
+      }).toThrow();
+    });
+  });
+
+  describe('updateAllowUsageTracking()', () => {
+    it('throws when no config is loaded', () => {
+      expect(() => {
+        config.updateAllowUsageTracking(true);
+      }).toThrow();
+    });
+  });
+
+  describe('isTrackingAllowed()', () => {
+    it('returns true when no config is loaded', () => {
+      expect(config.isTrackingAllowed()).toBe(true);
     });
   });
 });
diff --git a/errors/__tests__/fileSystemErrors.ts b/errors/__tests__/fileSystemErrors.ts
new file mode 100644
index 00000000..695d33e7
--- /dev/null
+++ b/errors/__tests__/fileSystemErrors.ts
@@ -0,0 +1,28 @@
+import { throwFileSystemError } from '../fileSystemErrors';
+import { BaseError } from '../../types/Error';
+
+export const newError = (overrides = {}): BaseError => {
+  return {
+    name: 'Error',
+    message: 'An error ocurred',
+    errno: 1,
+    code: 'error_code',
+    syscall: 'error_syscall',
+    errors: [],
+    ...overrides,
+  };
+};
+
+const fileSystemErrorContext = {
+  filepath: 'some/path',
+};
+
+describe('errors/fileSystemErrors', () => {
+  describe('throwFileSystemError()', () => {
+    it('throws a fileSystemError', () => {
+      expect(() => {
+        throwFileSystemError(newError(), fileSystemErrorContext);
+      }).toThrow();
+    });
+  });
+});
diff --git a/errors/fileSystemErrors.ts b/errors/fileSystemErrors.ts
index 1a9d6f0d..35f2bb48 100644
--- a/errors/fileSystemErrors.ts
+++ b/errors/fileSystemErrors.ts
@@ -4,6 +4,9 @@ import { BaseError, FileSystemErrorContext } from '../types/Error';
 
 const i18nKey = 'errors.fileSystemErrors';
 
+/**
+ * @throws
+ */
 export function throwFileSystemError(
   error: BaseError,
   context: FileSystemErrorContext
diff --git a/lib/__tests__/logger.ts b/lib/__tests__/logger.ts
new file mode 100644
index 00000000..2c9d2df0
--- /dev/null
+++ b/lib/__tests__/logger.ts
@@ -0,0 +1,146 @@
+import chalk from 'chalk';
+import {
+  Styles,
+  stylize,
+  setLogLevel,
+  getLogLevel,
+  LOG_LEVEL,
+  logger,
+  shouldLog,
+} from '../logging/logger';
+
+describe('lib/logging/logger', () => {
+  afterEach(() => {
+    setLogLevel(LOG_LEVEL.LOG);
+  });
+
+  describe('stylize()', () => {
+    it('stylizes input', () => {
+      const res = stylize('[ERROR]', Styles.error, ['test']);
+
+      expect(res[0]).toEqual(`${chalk.reset.red('[ERROR]')} test`);
+    });
+  });
+
+  describe('setLogLevel()', () => {
+    it('sets the log level for the logger', () => {
+      setLogLevel(LOG_LEVEL.DEBUG);
+      expect(getLogLevel()).toBe(LOG_LEVEL.DEBUG);
+
+      setLogLevel(LOG_LEVEL.WARN);
+      expect(getLogLevel()).toBe(LOG_LEVEL.WARN);
+
+      setLogLevel(LOG_LEVEL.NONE);
+      expect(getLogLevel()).toBe(LOG_LEVEL.NONE);
+    });
+  });
+
+  describe('shouldLog()', () => {
+    it('returns false for all logs when the currentLogLevel is NONE', () => {
+      setLogLevel(LOG_LEVEL.NONE);
+      expect(shouldLog(LOG_LEVEL.DEBUG)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.LOG)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.WARN)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.ERROR)).toBeFalsy();
+    });
+
+    it('returns true for all logs when the currentLogLevel is DEBUG', () => {
+      setLogLevel(LOG_LEVEL.DEBUG);
+      expect(shouldLog(LOG_LEVEL.DEBUG)).toBeTruthy();
+      expect(shouldLog(LOG_LEVEL.LOG)).toBeTruthy();
+      expect(shouldLog(LOG_LEVEL.WARN)).toBeTruthy();
+      expect(shouldLog(LOG_LEVEL.ERROR)).toBeTruthy();
+    });
+
+    it('returns false for debugs when the currentLogLevel is LOG', () => {
+      setLogLevel(LOG_LEVEL.LOG);
+      expect(shouldLog(LOG_LEVEL.DEBUG)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.LOG)).toBeTruthy();
+      expect(shouldLog(LOG_LEVEL.WARN)).toBeTruthy();
+      expect(shouldLog(LOG_LEVEL.ERROR)).toBeTruthy();
+    });
+
+    it('returns false for debugs and logs when the currentLogLevel is WARN', () => {
+      setLogLevel(LOG_LEVEL.WARN);
+      expect(shouldLog(LOG_LEVEL.DEBUG)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.LOG)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.WARN)).toBeTruthy();
+      expect(shouldLog(LOG_LEVEL.ERROR)).toBeTruthy();
+    });
+
+    it('returns false for debugs, logs, and warns when the currentLogLevel is ERROR', () => {
+      setLogLevel(LOG_LEVEL.ERROR);
+      expect(shouldLog(LOG_LEVEL.DEBUG)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.LOG)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.WARN)).toBeFalsy();
+      expect(shouldLog(LOG_LEVEL.ERROR)).toBeTruthy();
+    });
+  });
+
+  describe('logger()', () => {
+    let warnSpy: jest.SpyInstance;
+    let logSpy: jest.SpyInstance;
+    let debugSpy: jest.SpyInstance;
+    let infoSpy: jest.SpyInstance;
+    let groupSpy: jest.SpyInstance;
+    let groupEndSpy: jest.SpyInstance;
+
+    beforeEach(() => {
+      setLogLevel(LOG_LEVEL.LOG);
+      warnSpy = jest.spyOn(console, 'warn').mockImplementation(() => null);
+      logSpy = jest.spyOn(console, 'log').mockImplementation(() => null);
+      debugSpy = jest.spyOn(console, 'debug').mockImplementation(() => null);
+      infoSpy = jest.spyOn(console, 'info').mockImplementation(() => null);
+      groupSpy = jest.spyOn(console, 'group').mockImplementation(() => null);
+      groupEndSpy = jest
+        .spyOn(console, 'groupEnd')
+        .mockImplementation(() => null);
+    });
+
+    afterAll(() => {
+      warnSpy.mockReset();
+      logSpy.mockReset();
+      debugSpy.mockReset();
+      infoSpy.mockReset();
+      groupSpy.mockReset();
+      groupEndSpy.mockReset();
+    });
+
+    it('handles warnings', () => {
+      logger.log('test log');
+      expect(warnSpy).not.toHaveBeenCalled();
+
+      logger.warn('test log');
+      expect(warnSpy).toHaveBeenCalled();
+    });
+
+    it('handles logs', () => {
+      logger.debug('test log');
+      expect(debugSpy).not.toHaveBeenCalled();
+
+      logger.log('test log');
+      expect(logSpy).toHaveBeenCalled();
+
+      setLogLevel(LOG_LEVEL.DEBUG);
+      logger.debug('test log');
+      expect(debugSpy).toHaveBeenCalled();
+    });
+
+    it('handles info', () => {
+      logger.info('test log');
+      expect(infoSpy).toHaveBeenCalled();
+    });
+
+    it('handles success', () => {
+      logger.success('test log');
+      expect(logSpy).toHaveBeenCalled();
+    });
+
+    it('handles group and groupEnd', () => {
+      logger.group('test log');
+      logger.groupEnd();
+      expect(groupSpy).toHaveBeenCalled();
+      expect(groupEndSpy).toHaveBeenCalled();
+    });
+  });
+});
diff --git a/lib/__tests__/text.ts b/lib/__tests__/text.ts
new file mode 100644
index 00000000..ce81f0f2
--- /dev/null
+++ b/lib/__tests__/text.ts
@@ -0,0 +1,23 @@
+import { commaSeparatedValues } from '../text';
+
+describe('lib/text', () => {
+  describe('commaSeparatedValues()', () => {
+    it('returns a string with comma separated values', () => {
+      const res = commaSeparatedValues(['first', 'second', 'third']);
+
+      expect(res).toBe('first, second, and third');
+    });
+
+    it('supports a custom conjuction', async () => {
+      const res = commaSeparatedValues(['first', 'second', 'third'], 'custom');
+
+      expect(res).toBe('first, second, custom third');
+    });
+
+    it('supports a custom if empty case', async () => {
+      const res = commaSeparatedValues([], null, 'input is empty');
+
+      expect(res).toBe('input is empty');
+    });
+  });
+});
diff --git a/lib/logging/logger.ts b/lib/logging/logger.ts
index 98d5c7af..520d2170 100644
--- a/lib/logging/logger.ts
+++ b/lib/logging/logger.ts
@@ -90,8 +90,8 @@ export function setLogLevel(level: number): void {
   }
 }
 
-export function shouldLog(level: number): number {
-  return currentLogLevel & level;
+export function shouldLog(level: number): boolean {
+  return !!(currentLogLevel & level);
 }
 
 export function getLogLevel(): number {
diff --git a/lib/text.ts b/lib/text.ts
index c6e908e1..8fa08249 100644
--- a/lib/text.ts
+++ b/lib/text.ts
@@ -1,6 +1,6 @@
 export function commaSeparatedValues(
   arr: Array<string>,
-  conjunction = 'and',
+  conjunction: null | string = 'and',
   ifempty = ''
 ): string {
   const l = arr.length;