diff --git a/.circleci/config.yml b/.circleci/config.yml
new file mode 100644
index 00000000..ee52be24
--- /dev/null
+++ b/.circleci/config.yml
@@ -0,0 +1,124 @@
+---
+#
+#  This build use extensive use of parameters
+#  https://circleci.com/docs/reusing-config/#using-the-parameters-declaration
+#
+#  And Conditional Steps
+#  https://circleci.com/docs/reusing-config/#defining-conditional-steps
+
+version: 2.1
+
+orbs:
+  node: circleci/node@5.2.0
+
+commands:
+  project-setup:
+    parameters:
+      working-dir:
+        type: string
+      node-version:
+        type: string
+      windows:
+        type: boolean
+        default: false
+    steps:
+      - checkout:
+          path: << parameters.working-dir >>
+      - when:
+          condition:
+            equal: [ true, << parameters.windows >> ]
+          steps:
+            - run: 
+                name: nvm-install
+                command: choco install nvm -y
+            - run: 
+                name: node-install
+                command: |
+                    Start-Process powershell -verb runAs -Args "-start GeneralProfile"
+                    nvm install << parameters.node-version >>
+                    nvm use << parameters.node-version >>
+            - run:
+                name: npm-install
+                command: npm ci
+      - when:
+          condition:
+            equal: [ false, << parameters.windows >> ]
+          steps:
+            - node/install:
+                node-version: << parameters.node-version >>
+                install-yarn: false
+            - node/install-packages:
+                check-cache: always
+                pkg-manager: npm
+                with-cache: false
+
+  lint-test:
+    steps:
+      - run:
+          command: npm run posttest
+  
+  unit-test:
+    steps:
+      - run:
+          command: npm run test
+  
+
+executors:
+  linux: # a Linux VM running Ubuntu 20.04
+    docker:
+      - image: cimg/base:2024.01
+    working_directory: /home/circleci/project/c8
+  macos: # macos executor running Xcode
+    macos:
+      xcode: 14.2.0
+    working_directory: /Users/distiller/project/c8
+  win:
+    machine:
+      image: 'windows-server-2019-vs2019:2023.10.1'
+      resource_class: windows.medium
+      shell: powershell.exe -ExecutionPolicy Bypass
+    working_directory: C:\Users\circleci\project\c8
+
+jobs:
+  # Refactor to a command
+  test:
+    parameters:
+      os:
+        type: string
+      node-version:
+        type: string
+    executor: << parameters.os >>
+    steps:
+      - when:
+          condition: 
+            equal: [ linux, << parameters.os >> ]
+          steps: 
+            - project-setup:
+                node-version: << parameters.node-version >>
+                working-dir: /home/circleci/project/c8
+      - when:
+          condition: 
+            equal: [ win , << parameters.os >> ]
+          steps: 
+            - project-setup:
+                node-version: << parameters.node-version >>
+                working-dir: C:\Users\circleci\project\c8
+                windows: true
+      - when:
+          condition: 
+            equal: [ macos, << parameters.os >> ]
+          steps:
+            - project-setup:
+                node-version: << parameters.node-version >>
+                working-dir: /Users/distiller/project/c8
+      - lint-test
+      - unit-test
+
+workflows:
+  matrix-test:
+    jobs:
+      - test:
+          matrix:
+            parameters:
+              os: [win, linux, macos]
+              node-version: ["14.21.3", "16.20.2", "18.19.0", "20.11.0"]
\ No newline at end of file
diff --git a/README.md b/README.md
index a266a1da..2712e420 100644
--- a/README.md
+++ b/README.md
@@ -18,13 +18,25 @@ The above example will output coverage metrics for `foo.js`.
 
 ## CLI Options / Configuration
 
-c8 can be configured via command-line flags, a `c8` section in `package.json`, or a JSON configuration file on disk.
-
-A configuration file can be specified by passing its path on the command line with `--config` or `-c`. If no config option is provided, c8 searches for files named `.c8rc`, `.c8rc.json`, `.nycrc`, or `.nycrc.json`, starting from
-`cwd` and walking up the filesystem tree.
+c8 can be configured via command-line flags, a `c8` section in `package.json`, or a configuration file on disk.
 
 When using `package.json` configuration or a dedicated configuration file, omit the `--` prefix from the long-form of the desired command-line option.
 
+A configuration file can be specified by passing its path on the command line with `--config` or `-c`. If no config option is provided, c8 searches for files named in the table below starting from `cwd` and walking up the filesystem tree.
+
+A robust configuration file naming convention is available in an effort to stay compatible with nyc configuration options and ensure dynamic configuration.
+
+| File name                                                                                           | File Association   |
+|-----------------------------------------------------------------------------------------------------|--------------------|
+| `.c8rc`, `.c8rc.json`                                                                               | JSON               |
+| `.c8rc.yml`, `.c8rc.yaml`                                                                           | YAML               |
+| `.c8rc.js`, `.c8rc.cjs`, `.c8.config.js`, `.c8.config.cjs`, `c8.config.js`, `c8.config.cjs`         | CommonJS export*   |
+| `.nycrc`, `.nycrc.json`                                                                             | JSON               |
+| `.nycrc.yaml`, `.nycrc.yml`                                                                         | YAML               |
+| `.nycrc.js`, `.nycrc.cjs`, `nyc.config.js`, `nyc.config.cjs`, `.nyc.config.js`, `.nyc.config.cjs`   | CommonJS export*   |
+
+For packages written in ESM module syntax, a static configuration option is supported in JSON or YAML syntax. A dynamic configuration is also supported.  These configuration files must be written in CommonJS utilizing one of the .cjs file options in the table above. At the moment ESM syntax is not supported for writing c8 configuration files.  This may change in the future, but please note, C8 is written in CommonJS syntax.  
+
 Here is a list of common options. Run `c8 --help` for the full list and documentation.
 
 | Option | Description | Type | Default |
diff --git a/lib/error-reporting.js b/lib/error-reporting.js
new file mode 100644
index 00000000..353e7d6b
--- /dev/null
+++ b/lib/error-reporting.js
@@ -0,0 +1,69 @@
+/* TODO: Refactor:
+ *
+ * Not sure if this the name we want to use for this class
+ * In the parameters it supports an error that has already
+ * been thrown, then appends it's own error message
+ * Is there a more general name we can use like
+ * AppendableError or MultiError?  Is this a good
+ * Candidate for the decorator design pattern?
+ *
+ *
+ * Note: this is different than javascript Decorators
+ */
+/**
+ * To be thrown when there's a problem parsing a configuration file.
+ *
+ * More often than not the errors from the parsing engines are opaque and
+ * unhelpful, so this gives us the opportunity to provide better information
+ * to the user.
+ */
+class ConfigParsingError extends Error {
+  /**
+   * Constructs the error, given the path and error hints.
+   *
+   * @param {string} path The path to the file that had a parsing problem.
+   * @param {string} errorHints Any user-helpful hints.
+   * @param {unknown} [originalError] Optional: The original error thrown by the underlying parser.
+   */
+  constructor (path, errorHints, originalError) {
+    const originalErrorMessage =
+      originalError instanceof Error
+        ? ` Original error: ${originalError.message}`
+        : ''
+
+    super(
+      `Error loading configuration from file "${path}": ${errorHints}${originalErrorMessage}`
+    )
+
+    // this.name = ConfigParsingError.name
+
+    if (originalError instanceof Error) {
+      this.stack = originalError.stack
+    }
+  }
+}
+
+/**
+ * To be thrown when a file is loaded that is not one of the supported file
+ * types, especially when the file type is determined from the file extension.
+ */
+class UnsupportedFileTypeError extends Error {
+  /**
+   * Constructs the error, given the path and supported file types.
+   *
+   * @param {string} path The path to the file that is not supported.
+   * @param {string[]} supportedFileTypes An array of supported file types that will help the user understand when they need to do.
+   */
+  constructor (path, supportedFileTypes) {
+    const types = supportedFileTypes.join(', ')
+    super(
+      `Unsupported file type while reading file "${path}". Please make sure your file of one of the following file types: ${types}`
+    )
+    // this.name = UnsupportedFileTypeError.name
+  }
+}
+
+module.exports = {
+  ConfigParsingError,
+  UnsupportedFileTypeError
+}
diff --git a/lib/load-config.js b/lib/load-config.js
new file mode 100644
index 00000000..c484017e
--- /dev/null
+++ b/lib/load-config.js
@@ -0,0 +1,134 @@
+const { readFileSync } = require('fs')
+const { extname, basename } = require('path')
+const JsYaml = require('js-yaml')
+
+const {
+  UnsupportedFileTypeError,
+  ConfigParsingError
+} = require('./error-reporting')
+
+const CONFIG_FILE_NAMES = Object.freeze([
+  '.c8rc',
+  '.c8rc.json',
+  '.c8rc.yml',
+  '.c8rc.yaml',
+  '.c8rc.js',
+  '.c8rc.cjs',
+  '.c8.config.js',
+  '.c8.config.cjs',
+  'c8.config.js',
+  'c8.config.cjs',
+  '.nycrc',
+  '.nycrc.json',
+  '.nycrc.yml',
+  '.nycrc.yaml',
+  '.nyc.config.js',
+  '.nyc.config.cjs',
+  'nyc.config.js',
+  'nyc.config.cjs'
+])
+
+const JS_EXTS = Object.freeze(['.js', '.cjs'])
+const JSON_EXTS = Object.freeze(['.json'])
+const YAML_EXTS = Object.freeze(['.yml', '.yaml'])
+
+const NO_EXPORTS = Symbol('no exports')
+
+/**
+ * Loads a configuration file of whatever format from the given path.
+ *
+ * @param {string} path The path to load the configuration from.
+ * @param {readFile(path: string) => string, readJs(path: string) => C8Config} [_di] For test suite use only. Do not use.
+ * @returns {object} An object containing
+ * @throws {UnsupportedFileTypeError} When the given configuration file is of a type that is unsupported.
+ * @throws {ConfigParsingError} When the configuration file fails to be read. E.g. a syntax error, such as not using quoted keys in JSON.
+ */
+function loadConfigFile (path, _di) {
+  const di = {
+    // A variation of the Dependency Injection pattern that allows the test suites to overide any of these functions with mocks.
+    readFile: (path) => readFileSync(path, 'utf8'),
+    readJs: (path) => require(path),
+    ..._di // Note that making the DI argument a hidden argument by using the `arguments` array isn't a viable option in TypeScript, so this has been written in a way that is compatible with that.
+  }
+
+  let config
+
+  const fileName = basename(path)
+  const ext = extname(path).toLowerCase()
+
+  if (YAML_EXTS.includes(ext)) {
+    try {
+      // TODO: add YAML schema so that we get better errors for YAML users.
+      config = JsYaml.load(di.readFile(path))
+    } catch (error) {
+      if (error instanceof JsYaml.YAMLException) {
+        throw new ConfigParsingError(
+          path,
+          'must contain a valid c8 configuration object.',
+          error
+        )
+      }
+
+      throw error
+    }
+
+    if (!config) {
+      // TODO: remove this check once we get YAML schema validation.
+      throw new ConfigParsingError(path, 'invalid configuration')
+    }
+  } else if (JS_EXTS.includes(ext)) {
+    // Add a loader that allows us to check to see if anything was ever exported.
+    // Thank you to https://stackoverflow.com/a/70999950 for the inspiration. Please note that this code won't port to TypeScript nicely.
+    const extensions = module.constructor._extensions
+    const cjsLoader = extensions['.cjs']
+    const jsLoader = extensions['.js']
+    extensions['.cjs'] = extensions['.js'] = (module, filename) => {
+      module.exports[NO_EXPORTS] = filename
+      jsLoader(module, filename)
+    }
+    try {
+      config = di.readJs(path)
+    } finally {
+      // Undo the global state mutation, even if an error was thrown.
+      extensions['.cjs'] = cjsLoader
+      extensions['.js'] = jsLoader
+    }
+    if (NO_EXPORTS in config) {
+      throw new ConfigParsingError(
+        path,
+        'does not export a c8 configuration object.'
+      )
+    }
+  } else if (JSON_EXTS.includes(ext) || CONFIG_FILE_NAMES.includes(fileName)) {
+    try {
+      config = JSON.parse(di.readFile(path))
+    } catch (error) {
+      if (error instanceof SyntaxError) {
+        throw new ConfigParsingError(
+          path,
+          'must contain a valid c8 configuration object.',
+          error
+        )
+      }
+
+      throw error
+    }
+  } else {
+    // If the user supplied a bad configuration file that we can't figure out how to read, then it's on them to solve it.
+    // Attempting to use some other config, even a default one, will result in unexpected behavior: aka ignoring the config that was explicitly specified is not intuitive.
+    throw new UnsupportedFileTypeError(path, [
+      ...JSON_EXTS,
+      ...JS_EXTS,
+      ...YAML_EXTS
+    ])
+  }
+
+  // TODO: validate the object schema so that we get validation of JS-like configs. Might want to refactor the above test cases so that the YAML isn't being validated twice.
+
+  return config
+}
+
+module.exports = {
+  CONFIG_FILE_NAMES,
+  loadConfigFile
+}
diff --git a/lib/parse-args.js b/lib/parse-args.js
index 21a9cd7a..40a9d1dd 100644
--- a/lib/parse-args.js
+++ b/lib/parse-args.js
@@ -1,24 +1,25 @@
 const defaultExclude = require('@istanbuljs/schema/default-exclude')
 const defaultExtension = require('@istanbuljs/schema/default-extension')
 const findUp = require('find-up')
-const { readFileSync } = require('fs')
 const Yargs = require('yargs/yargs')
 const { applyExtends } = require('yargs/helpers')
 const parser = require('yargs-parser')
 const { resolve } = require('path')
 
+const { CONFIG_FILE_NAMES, loadConfigFile } = require('./load-config')
+
 function buildYargs (withCommands = false) {
   const yargs = Yargs([])
     .usage('$0 [opts] [script] [opts]')
     .options('config', {
       alias: 'c',
       config: true,
-      describe: 'path to JSON configuration file',
+      describe: 'path to configuration file',
       configParser: (path) => {
-        const config = JSON.parse(readFileSync(path))
+        const config = loadConfigFile(path)
         return applyExtends(config, process.cwd(), true)
       },
-      default: () => findUp.sync(['.c8rc', '.c8rc.json', '.nycrc', '.nycrc.json'])
+      default: () => findUp.sync(CONFIG_FILE_NAMES)
     })
     .option('reporter', {
       alias: 'r',
diff --git a/package-lock.json b/package-lock.json
index 2c60c943..4df36c53 100644
--- a/package-lock.json
+++ b/package-lock.json
@@ -16,6 +16,7 @@
         "istanbul-lib-coverage": "^3.2.0",
         "istanbul-lib-report": "^3.0.1",
         "istanbul-reports": "^3.1.6",
+        "js-yaml": "^4.1.0",
         "test-exclude": "^6.0.0",
         "v8-to-istanbul": "^9.0.0",
         "yargs": "^17.7.2",
@@ -222,9 +223,9 @@
       "dev": true
     },
     "node_modules/@types/node": {
-      "version": "20.10.6",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.10.6.tgz",
-      "integrity": "sha512-Vac8H+NlRNNlAmDfGUP7b5h/KA+AtWIzuXy0E6OyP8f1tCLYAtPvKRRDJjAPqhpCb0t6U2j7/xqAuLEebW2kiw==",
+      "version": "20.10.7",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.10.7.tgz",
+      "integrity": "sha512-fRbIKb8C/Y2lXxB5eVMj4IU7xpdox0Lh8bUPEdtLysaylsml1hOOx1+STloRs/B9nf7C6kPRmmg/V7aQW7usNg==",
       "dev": true,
       "dependencies": {
         "undici-types": "~5.26.4"
@@ -334,8 +335,7 @@
     "node_modules/argparse": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/argparse/-/argparse-2.0.1.tgz",
-      "integrity": "sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q==",
-      "dev": true
+      "integrity": "sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q=="
     },
     "node_modules/array-buffer-byte-length": {
       "version": "1.0.0",
@@ -533,9 +533,9 @@
       }
     },
     "node_modules/chai": {
-      "version": "4.3.10",
-      "resolved": "https://registry.npmjs.org/chai/-/chai-4.3.10.tgz",
-      "integrity": "sha512-0UXG04VuVbruMUYbJ6JctvH0YnC/4q3/AkT18q4NaITo91CUm0liMS9VqzT9vZhVQ/1eqPanMWjBM+Juhfb/9g==",
+      "version": "4.4.0",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-4.4.0.tgz",
+      "integrity": "sha512-x9cHNq1uvkCdU+5xTkNh5WtgD4e4yDFCsp9jVc7N7qVeKeftv3gO/ZrviX5d+3ZfxdYnZXZYujjRInu1RogU6A==",
       "dev": true,
       "dependencies": {
         "assertion-error": "^1.1.0",
@@ -2463,7 +2463,6 @@
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-4.1.0.tgz",
       "integrity": "sha512-wpxZs9NoxZaJESJGIZTyDEaYpl0FKSA+FB9aJiyemKhMwkxQg63h4T1KJgUGHpTqPDNRcmmYLugrRjJlBtWvRA==",
-      "dev": true,
       "dependencies": {
         "argparse": "^2.0.1"
       },
@@ -4737,9 +4736,9 @@
       "dev": true
     },
     "@types/node": {
-      "version": "20.10.6",
-      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.10.6.tgz",
-      "integrity": "sha512-Vac8H+NlRNNlAmDfGUP7b5h/KA+AtWIzuXy0E6OyP8f1tCLYAtPvKRRDJjAPqhpCb0t6U2j7/xqAuLEebW2kiw==",
+      "version": "20.10.7",
+      "resolved": "https://registry.npmjs.org/@types/node/-/node-20.10.7.tgz",
+      "integrity": "sha512-fRbIKb8C/Y2lXxB5eVMj4IU7xpdox0Lh8bUPEdtLysaylsml1hOOx1+STloRs/B9nf7C6kPRmmg/V7aQW7usNg==",
       "dev": true,
       "requires": {
         "undici-types": "~5.26.4"
@@ -4822,8 +4821,7 @@
     "argparse": {
       "version": "2.0.1",
       "resolved": "https://registry.npmjs.org/argparse/-/argparse-2.0.1.tgz",
-      "integrity": "sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q==",
-      "dev": true
+      "integrity": "sha512-8+9WqebbFzpX9OR+Wa6O29asIogeRMzcGtAINdpMHHyAg10f05aSFVBbcEqGf/PXw1EjAZ+q2/bEBg3DvurK3Q=="
     },
     "array-buffer-byte-length": {
       "version": "1.0.0",
@@ -4964,9 +4962,9 @@
       "dev": true
     },
     "chai": {
-      "version": "4.3.10",
-      "resolved": "https://registry.npmjs.org/chai/-/chai-4.3.10.tgz",
-      "integrity": "sha512-0UXG04VuVbruMUYbJ6JctvH0YnC/4q3/AkT18q4NaITo91CUm0liMS9VqzT9vZhVQ/1eqPanMWjBM+Juhfb/9g==",
+      "version": "4.4.0",
+      "resolved": "https://registry.npmjs.org/chai/-/chai-4.4.0.tgz",
+      "integrity": "sha512-x9cHNq1uvkCdU+5xTkNh5WtgD4e4yDFCsp9jVc7N7qVeKeftv3gO/ZrviX5d+3ZfxdYnZXZYujjRInu1RogU6A==",
       "dev": true,
       "requires": {
         "assertion-error": "^1.1.0",
@@ -6380,7 +6378,6 @@
       "version": "4.1.0",
       "resolved": "https://registry.npmjs.org/js-yaml/-/js-yaml-4.1.0.tgz",
       "integrity": "sha512-wpxZs9NoxZaJESJGIZTyDEaYpl0FKSA+FB9aJiyemKhMwkxQg63h4T1KJgUGHpTqPDNRcmmYLugrRjJlBtWvRA==",
-      "dev": true,
       "requires": {
         "argparse": "^2.0.1"
       }
diff --git a/package.json b/package.json
index 59446446..4ef63bf7 100644
--- a/package.json
+++ b/package.json
@@ -40,6 +40,7 @@
     "istanbul-lib-coverage": "^3.2.0",
     "istanbul-lib-report": "^3.0.1",
     "istanbul-reports": "^3.1.6",
+    "js-yaml": "^4.1.0",
     "test-exclude": "^6.0.0",
     "v8-to-istanbul": "^9.0.0",
     "yargs": "^17.7.2",
diff --git a/test/error-reporting.js b/test/error-reporting.js
new file mode 100644
index 00000000..2dfc2f51
--- /dev/null
+++ b/test/error-reporting.js
@@ -0,0 +1,67 @@
+/* global describe, it */
+
+const { expect } = require('chai')
+
+const {
+  UnsupportedFileTypeError,
+  ConfigParsingError
+} = require('../lib/error-reporting')
+
+describe(__filename, () => {
+  describe(ConfigParsingError.name, () => {
+    it('is an Error subclass', () => {
+      expect(new ConfigParsingError('', '')).to.be.instanceof(Error)
+    })
+
+    it('has the correct static name property', () => {
+      expect(ConfigParsingError).to.have.property('name', 'ConfigParsingError')
+    })
+
+    it('creates the correct error message when not provided an original error', () => {
+      expect(
+        new ConfigParsingError('path/goes/here', 'a hint.')
+      ).to.have.property(
+        'message',
+        'Error loading configuration from file "path/goes/here": a hint.'
+      )
+    })
+
+    it('creates the correct error message when provided an original error', () => {
+      expect(
+        new ConfigParsingError(
+          'path/goes/here',
+          'a hint.',
+          new Error('some error thrown by a parsing engine')
+        )
+      ).to.have.property(
+        'message',
+        'Error loading configuration from file "path/goes/here": a hint. Original error: some error thrown by a parsing engine'
+      )
+    })
+  })
+
+  describe(UnsupportedFileTypeError.name, () => {
+    it('is an Error subclass', () => {
+      expect(new UnsupportedFileTypeError('', [])).to.be.instanceof(Error)
+    })
+
+    it('has the correct static name property', () => {
+      expect(UnsupportedFileTypeError).to.have.property(
+        'name',
+        'UnsupportedFileTypeError'
+      )
+    })
+
+    it('creates the correct error message', () => {
+      expect(
+        new UnsupportedFileTypeError('path/goes/here', [
+          'fileType1',
+          'fileType2'
+        ])
+      ).to.have.property(
+        'message',
+        'Unsupported file type while reading file "path/goes/here". Please make sure your file of one of the following file types: fileType1, fileType2'
+      )
+    })
+  })
+})
diff --git a/test/fixtures/config/.c8.config.cjs b/test/fixtures/config/.c8.config.cjs
new file mode 100644
index 00000000..290e529a
--- /dev/null
+++ b/test/fixtures/config/.c8.config.cjs
@@ -0,0 +1,11 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 45,
+  "branches": "72",
+  "statements": "65"
+}
+
+module.exports = config
diff --git a/test/fixtures/config/.c8.config.js b/test/fixtures/config/.c8.config.js
new file mode 100644
index 00000000..4e420f80
--- /dev/null
+++ b/test/fixtures/config/.c8.config.js
@@ -0,0 +1,11 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 47,
+  "branches": "72",
+  "statements": "65"
+}
+
+module.exports = config
diff --git a/test/fixtures/config/.c8.config.py b/test/fixtures/config/.c8.config.py
new file mode 100644
index 00000000..290e529a
--- /dev/null
+++ b/test/fixtures/config/.c8.config.py
@@ -0,0 +1,11 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 45,
+  "branches": "72",
+  "statements": "65"
+}
+
+module.exports = config
diff --git a/test/fixtures/config/.c8rc b/test/fixtures/config/.c8rc
new file mode 100644
index 00000000..acbcfcee
--- /dev/null
+++ b/test/fixtures/config/.c8rc
@@ -0,0 +1,10 @@
+  {
+    "reporter": [
+      "lcov",
+      "json"
+    ],
+    "statements": 29,
+    "branches": 81,
+    "lines": 78,
+    "functions": 93
+  }
diff --git a/test/fixtures/config/.c8rc.cjs b/test/fixtures/config/.c8rc.cjs
new file mode 100644
index 00000000..52218a57
--- /dev/null
+++ b/test/fixtures/config/.c8rc.cjs
@@ -0,0 +1,11 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 32,
+  "branches": "72",
+  "statements": "65"
+}
+
+module.exports = config
diff --git a/test/fixtures/config/.c8rc.js b/test/fixtures/config/.c8rc.js
new file mode 100644
index 00000000..b13cb027
--- /dev/null
+++ b/test/fixtures/config/.c8rc.js
@@ -0,0 +1,11 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 22,
+  "branches": "72",
+  "statements": "65"
+}
+
+module.exports = config
diff --git a/test/fixtures/config/.c8rc.yaml b/test/fixtures/config/.c8rc.yaml
new file mode 100644
index 00000000..fb8519bb
--- /dev/null
+++ b/test/fixtures/config/.c8rc.yaml
@@ -0,0 +1,8 @@
+---
+reporter:
+- html
+- text
+statements: 83
+branches: 88
+lines: 10
+functions: 12
diff --git a/test/fixtures/config/.c8rc.yml b/test/fixtures/config/.c8rc.yml
new file mode 100644
index 00000000..93795b31
--- /dev/null
+++ b/test/fixtures/config/.c8rc.yml
@@ -0,0 +1,8 @@
+---
+reporter:
+- html
+- text
+statements: 89
+branches: 58
+lines: 69
+functions: 54
diff --git a/test/fixtures/config/.nyc.config.cjs b/test/fixtures/config/.nyc.config.cjs
new file mode 100644
index 00000000..cda7b494
--- /dev/null
+++ b/test/fixtures/config/.nyc.config.cjs
@@ -0,0 +1,12 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "statements": 54,
+  "branches": 40,
+  "lines": 71,
+  "functions": 0
+}
+
+module.exports = config
diff --git a/test/fixtures/config/.nyc.config.js b/test/fixtures/config/.nyc.config.js
new file mode 100644
index 00000000..19ca1525
--- /dev/null
+++ b/test/fixtures/config/.nyc.config.js
@@ -0,0 +1,12 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "statements": 54,
+  "branches": 40,
+  "lines": 85,
+  "functions": 0
+}
+
+module.exports = config
diff --git a/test/fixtures/config/.nycrc b/test/fixtures/config/.nycrc
new file mode 100644
index 00000000..ed44728c
--- /dev/null
+++ b/test/fixtures/config/.nycrc
@@ -0,0 +1,7 @@
+  {
+    "statements": 95,
+    "branches": 40,
+    "lines": 51,
+    "functions": 89
+  }
+  
\ No newline at end of file
diff --git a/test/fixtures/config/.nycrc.json b/test/fixtures/config/.nycrc.json
new file mode 100644
index 00000000..b9c9a301
--- /dev/null
+++ b/test/fixtures/config/.nycrc.json
@@ -0,0 +1,9 @@
+{
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 96,
+  "branches": "82",
+  "statements": "95"
+}
diff --git a/test/fixtures/config/.nycrc.yaml b/test/fixtures/config/.nycrc.yaml
new file mode 100644
index 00000000..c7d8c2ff
--- /dev/null
+++ b/test/fixtures/config/.nycrc.yaml
@@ -0,0 +1,7 @@
+---
+reporter:
+- html
+- text
+lines: 98
+branches: '82'
+statements: '95'
diff --git a/test/fixtures/config/.nycrc.yml b/test/fixtures/config/.nycrc.yml
new file mode 100644
index 00000000..602b4999
--- /dev/null
+++ b/test/fixtures/config/.nycrc.yml
@@ -0,0 +1,7 @@
+---
+reporter:
+- html
+- text
+lines: 99
+branches: '82'
+statements: '95'
diff --git a/test/fixtures/config/blank.cjs b/test/fixtures/config/blank.cjs
new file mode 100644
index 00000000..e69de29b
diff --git a/test/fixtures/config/blank.js b/test/fixtures/config/blank.js
new file mode 100644
index 00000000..e69de29b
diff --git a/test/fixtures/config/c8.config.cjs b/test/fixtures/config/c8.config.cjs
new file mode 100644
index 00000000..400266dc
--- /dev/null
+++ b/test/fixtures/config/c8.config.cjs
@@ -0,0 +1,12 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "statements": 95,
+  "branches": 40,
+  "lines": 51,
+  "functions": 89
+}
+
+module.exports = config
diff --git a/test/fixtures/config/c8.config.js b/test/fixtures/config/c8.config.js
new file mode 100644
index 00000000..e23d4ae5
--- /dev/null
+++ b/test/fixtures/config/c8.config.js
@@ -0,0 +1,12 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "statements": 54,
+  "branches": 40,
+  "lines": 47,
+  "functions": 0
+}
+
+module.exports = config
diff --git a/test/fixtures/config/nonstandard.json b/test/fixtures/config/nonstandard.json
new file mode 100644
index 00000000..00e307d1
--- /dev/null
+++ b/test/fixtures/config/nonstandard.json
@@ -0,0 +1,5 @@
+{
+  "temp-directory": "./foo",
+  "lines": 420,
+  "functions": 24
+}
diff --git a/test/fixtures/config/nyc.config.cjs b/test/fixtures/config/nyc.config.cjs
new file mode 100644
index 00000000..c602be3b
--- /dev/null
+++ b/test/fixtures/config/nyc.config.cjs
@@ -0,0 +1,11 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 94,
+  "branches": "82",
+  "statements": "95"
+}
+
+module.exports = config
diff --git a/test/fixtures/config/nyc.config.js b/test/fixtures/config/nyc.config.js
new file mode 100644
index 00000000..6b03355c
--- /dev/null
+++ b/test/fixtures/config/nyc.config.js
@@ -0,0 +1,11 @@
+const config = {
+  "reporter": [
+    "html",
+    "text"
+  ],
+  "lines": 95,
+  "branches": "82",
+  "statements": "95"
+}
+
+module.exports = config
diff --git a/test/integration.js.snap b/test/integration.js.snap
index a9279c7e..ee9d0bbe 100644
--- a/test/integration.js.snap
+++ b/test/integration.js.snap
@@ -156,7 +156,7 @@ hey
 ---------------------------------------|---------|----------|---------|---------|------------------------
 File                                   | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s      
 ---------------------------------------|---------|----------|---------|---------|------------------------
-All files                              |    3.52 |     12.5 |    6.52 |    3.52 |                        
+All files                              |    3.03 |    10.71 |    5.55 |    3.03 |                        
  c8                                    |       0 |        0 |       0 |       0 |                        
   index.js                             |       0 |        0 |       0 |       0 | 1                      
  c8/bin                                |       0 |        0 |       0 |       0 |                        
@@ -166,7 +166,9 @@ All files                              |    3.52 |     12.5 |    6.52 |    3.52
   prettify.js                          |       0 |        0 |       0 |       0 | 1-2                    
   sorter.js                            |       0 |        0 |       0 |       0 | 1-196                  
  c8/lib                                |       0 |        0 |       0 |       0 |                        
-  parse-args.js                        |       0 |        0 |       0 |       0 | 1-224                  
+  error-reporting.js                   |       0 |        0 |       0 |       0 | 1-69                   
+  load-config.js                       |       0 |        0 |       0 |       0 | 1-134                  
+  parse-args.js                        |       0 |        0 |       0 |       0 | 1-225                  
   report.js                            |       0 |        0 |       0 |       0 | 1-402                  
   source-map-from-file.js              |       0 |        0 |       0 |       0 | 1-100                  
  c8/lib/commands                       |       0 |        0 |       0 |       0 |                        
@@ -194,6 +196,13 @@ All files                              |    3.52 |     12.5 |    6.52 |    3.52
   main.js                              |       0 |        0 |       0 |       0 | 1-4                    
  c8/test/fixtures/all/vanilla/dir      |       0 |        0 |       0 |       0 |                        
   unloaded.js                          |       0 |        0 |       0 |       0 | 1-5                    
+ c8/test/fixtures/config               |       0 |        0 |       0 |       0 |                        
+  .c8.config.js                        |       0 |        0 |       0 |       0 | 1-11                   
+  .c8rc.js                             |       0 |        0 |       0 |       0 | 1-11                   
+  .nyc.config.js                       |       0 |        0 |       0 |       0 | 1-12                   
+  blank.js                             |       0 |        0 |       0 |       0 | 1                      
+  c8.config.js                         |       0 |        0 |       0 |       0 | 1-12                   
+  nyc.config.js                        |       0 |        0 |       0 |       0 | 1-11                   
  c8/test/fixtures/multidir1            |       0 |        0 |       0 |       0 |                        
   file1.js                             |       0 |        0 |       0 |       0 | 1                      
  c8/test/fixtures/multidir2            |       0 |        0 |       0 |       0 |                        
@@ -521,7 +530,7 @@ hey
 ---------------------------------------|---------|----------|---------|---------|------------------------
 File                                   | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s      
 ---------------------------------------|---------|----------|---------|---------|------------------------
-All files                              |    3.52 |     12.5 |    6.52 |    3.52 |                        
+All files                              |    3.03 |    10.71 |    5.55 |    3.03 |                        
  c8                                    |       0 |        0 |       0 |       0 |                        
   index.js                             |       0 |        0 |       0 |       0 | 1                      
  c8/bin                                |       0 |        0 |       0 |       0 |                        
@@ -531,7 +540,9 @@ All files                              |    3.52 |     12.5 |    6.52 |    3.52
   prettify.js                          |       0 |        0 |       0 |       0 | 1-2                    
   sorter.js                            |       0 |        0 |       0 |       0 | 1-196                  
  c8/lib                                |       0 |        0 |       0 |       0 |                        
-  parse-args.js                        |       0 |        0 |       0 |       0 | 1-224                  
+  error-reporting.js                   |       0 |        0 |       0 |       0 | 1-69                   
+  load-config.js                       |       0 |        0 |       0 |       0 | 1-134                  
+  parse-args.js                        |       0 |        0 |       0 |       0 | 1-225                  
   report.js                            |       0 |        0 |       0 |       0 | 1-402                  
   source-map-from-file.js              |       0 |        0 |       0 |       0 | 1-100                  
  c8/lib/commands                       |       0 |        0 |       0 |       0 |                        
@@ -559,6 +570,13 @@ All files                              |    3.52 |     12.5 |    6.52 |    3.52
   main.js                              |       0 |        0 |       0 |       0 | 1-4                    
  c8/test/fixtures/all/vanilla/dir      |       0 |        0 |       0 |       0 |                        
   unloaded.js                          |       0 |        0 |       0 |       0 | 1-5                    
+ c8/test/fixtures/config               |       0 |        0 |       0 |       0 |                        
+  .c8.config.js                        |       0 |        0 |       0 |       0 | 1-11                   
+  .c8rc.js                             |       0 |        0 |       0 |       0 | 1-11                   
+  .nyc.config.js                       |       0 |        0 |       0 |       0 | 1-12                   
+  blank.js                             |       0 |        0 |       0 |       0 | 1                      
+  c8.config.js                         |       0 |        0 |       0 |       0 | 1-12                   
+  nyc.config.js                        |       0 |        0 |       0 |       0 | 1-11                   
  c8/test/fixtures/multidir1            |       0 |        0 |       0 |       0 |                        
   file1.js                             |       0 |        0 |       0 |       0 | 1                      
  c8/test/fixtures/multidir2            |       0 |        0 |       0 |       0 |                        
diff --git a/test/load-config-helper.js b/test/load-config-helper.js
new file mode 100644
index 00000000..93b39d1a
--- /dev/null
+++ b/test/load-config-helper.js
@@ -0,0 +1,34 @@
+const { mkdirSync, copyFileSync, rmSync, existsSync } = require('fs')
+const { join } = require('path')
+
+const testPath = './test/fixtures/tmp-config-test'
+
+const testConfigFile = function (filePath, fileNameLineNumberMap, callback) {
+  Object.keys(fileNameLineNumberMap).forEach((fileName) => {
+    const expectedLines = fileNameLineNumberMap[fileName]
+    callback(fileName, expectedLines)
+  })
+}
+
+const beforeTestReadingConfigFile = (configFileName) => {
+  afterTestReadingConfigFile()
+  // make the directory tmp-config-test
+  mkdirSync(testPath)
+
+  // Copy config file in fileName and test/fixtures/normal.js to dir above
+  copyFileSync('./test/fixtures/normal.js', join(testPath, '/normal.js'))
+  copyFileSync('./test/fixtures/async.js', join(testPath, '/async.js'))
+  copyFileSync('./test/fixtures/config/' + configFileName, join(testPath, configFileName))
+}
+
+const afterTestReadingConfigFile = () => {
+  if (existsSync(testPath)) {
+    rmSync(testPath, { recursive: true, force: true })
+  }
+}
+
+module.exports = {
+  testConfigFile: testConfigFile,
+  beforeTestReadingConfigFile: beforeTestReadingConfigFile,
+  afterTestReadingConfigFile: afterTestReadingConfigFile
+}
diff --git a/test/load-config.js b/test/load-config.js
new file mode 100644
index 00000000..ed2b7893
--- /dev/null
+++ b/test/load-config.js
@@ -0,0 +1,336 @@
+/* global describe, it, beforeEach, after */
+
+const { assert, expect } = require('chai')
+const { existsSync } = require('fs')
+const { join } = require('path')
+const { buildYargs } = require('../lib/parse-args')
+const chaiJestSnapshot = require('chai-jest-snapshot')
+const { spawnSync } = require('child_process')
+
+const {
+  UnsupportedFileTypeError,
+  ConfigParsingError
+} = require('../lib/error-reporting')
+const { CONFIG_FILE_NAMES, loadConfigFile } = require('../lib/load-config')
+
+const {
+  testConfigFile,
+  beforeTestReadingConfigFile,
+  afterTestReadingConfigFile
+} = require('./load-config-helper.js')
+
+const c8Path = require.resolve('../bin/c8')
+const nodePath = process.execPath
+
+describe(__filename, () => {
+  const baseDI = {
+    // These specify default functions for all the DI calls.
+    // Each should throw an error if called so that the tests have to override the ones that are expected.
+    // Any test that actually fails with one of these errors was either not set up correctly or the code that's being tested isn't writen correctly.
+    readFile () {
+      throw new Error('Test not set up to handle calls to readFile!')
+    },
+    readJs () {
+      throw new Error('Test not set up to handle calls to readJs!')
+    }
+  }
+
+  describe(loadConfigFile.name, () => {
+    it('config directory should contain all variations of the config file naming convention', () => {
+      let count = 0
+      const fileMessages = []
+      CONFIG_FILE_NAMES.forEach((file) => {
+        const fullPath = './test/fixtures/config/' + file
+        if (existsSync(fullPath)) {
+          count++
+        } else {
+          fileMessages.push(
+            `Missing ${file} from ./test/fixtures/config directory`
+          )
+        }
+      })
+
+      if (count === CONFIG_FILE_NAMES.length) {
+        assert.equal(count, CONFIG_FILE_NAMES.length)
+      } else {
+        const msg = fileMessages.join(' \n      ')
+        assert.equal(fileMessages.length, 0, msg)
+      }
+    })
+
+    describe('should be able to read config files with .json, .yml, .yaml, .js, .cjs extensions', () => {
+      const filePath = './fixtures/config/'
+      const testData = {
+        c8: {
+          description: 'c8 variations of config file',
+          fileNameLineNumberMap: {
+            '.c8rc.json': 101,
+            '.c8rc.yml': 69,
+            '.c8rc.yaml': 10,
+            'c8.config.js': 47,
+            'c8.config.cjs': 51,
+            '.c8rc.js': 22,
+            '.c8rc.cjs': 32,
+            '.c8.config.js': 47,
+            '.c8.config.cjs': 45
+          }
+        },
+        nyc: {
+          description: 'nyc variations of config file',
+          fileNameLineNumberMap: {
+            '.nycrc': 51,
+            '.nycrc.json': 96,
+            '.nycrc.yml': 99,
+            '.nycrc.yaml': 98,
+            'nyc.config.js': 95,
+            'nyc.config.cjs': 94,
+            '.nyc.config.js': 85,
+            '.nyc.config.cjs': 71
+          }
+        }
+      }
+
+      Object.keys(testData).forEach((key) => {
+        const { description, fileNameLineNumberMap } = testData[key]
+        describe(description, function () {
+          testConfigFile(
+            filePath,
+            fileNameLineNumberMap,
+            function (fileName, expectedLines) {
+              beforeEach(() => beforeTestReadingConfigFile(fileName))
+              it(`should be able to resolve config file ${fileName} with --config flag`, () => {
+                const configFilePath = join(filePath, fileName)
+                const argv = buildYargs().parse([
+                  'node',
+                  'c8',
+                  'my-app',
+                  '--config',
+                  require.resolve(`./${configFilePath}`)
+                ])
+                argv.lines.should.be.equal(expectedLines)
+              })
+
+              // skipping for the moment.  Need another patch for this test to successfully run
+              it.skip(`should be able to resolve config file ${fileName} by detection`, function () {
+                // set the snapshot filename
+                chaiJestSnapshot.setTestName(
+                  `should be able to resolve config file ${fileName} by detection`
+                )
+                chaiJestSnapshot.setFilename(
+                  './test/fixtures/config/snapshots/' + fileName + '.snap'
+                )
+
+                // Run V8 in the dir above
+                const { output } = spawnSync(
+                  nodePath,
+                  [
+                    c8Path,
+                    '--temp-directory=tmp/normal',
+                    '--all',
+                    '--src=./test/fixtures/tmp-config-test',
+                    nodePath,
+                    require.resolve('./fixtures/tmp-config-test/normal.js')
+                  ],
+                  { cwd: './test/fixtures/tmp-config-test' }
+                )
+                output.toString('utf8').should.matchSnapshot()
+              })
+              after(afterTestReadingConfigFile)
+            }
+          )
+        })
+      })
+    })
+
+    it('throws an error message if an invalid configuration file name is passed', function () {
+      const invalidConfig = './fixtures/config/.c8.config.py'
+
+      expect(() => loadConfigFile(invalidConfig, baseDI)).to.throw(
+        UnsupportedFileTypeError
+      )
+    })
+
+    describe('handles file extensions in a case insensitive manner', () => {
+      for (const ext of ['.jSoN', '.JSON']) {
+        it(`reads a JSON file with extension ${ext}`, () => {
+          expect(
+            loadConfigFile(`test${ext}`, {
+              ...baseDI,
+              readFile: () => '{"statements":12}'
+            })
+          ).to.deep.equal({ statements: 12 })
+        })
+      }
+
+      for (const ext of ['.CJS', '.CJs', '.jS', '.JS']) {
+        it(`reads a Common JS file with extension ${ext}`, () => {
+          expect(
+            loadConfigFile(`test${ext}`, {
+              ...baseDI,
+              readJs: () => ({
+                statements: 12
+              })
+            })
+          ).to.deep.equal({ statements: 12 })
+        })
+      }
+
+      for (const ext of ['.Yml', '.YAML']) {
+        it(`reads a YAML file with extension ${ext}`, () => {
+          expect(
+            loadConfigFile(`test${ext}`, {
+              ...baseDI,
+              readFile: () => 'statements: 12'
+            })
+          ).to.deep.equal({ statements: 12 })
+        })
+      }
+    })
+
+    describe('.json', () => {
+      it('throws an error if the JSON file is empty', () => {
+        expect(() =>
+          loadConfigFile('test.json', {
+            ...baseDI,
+            readFile: () => ''
+          })
+        ).to.throw(ConfigParsingError, /Unexpected end of JSON input/)
+      })
+
+      it('throws an error if the JSON file is invalid JSON', () => {
+        expect(() =>
+          loadConfigFile('test.json', {
+            ...baseDI,
+            readFile: () => 'not valid json'
+          })
+        ).to.throw(ConfigParsingError, /Unexpected token /)
+      })
+
+      it('returns an empty config if the JSON file has an empty object', () => {
+        expect(
+          loadConfigFile('test.json', {
+            ...baseDI,
+            readFile: () => '{}'
+          })
+        ).to.deep.equal({})
+      })
+
+      it('throws the expected error if the file reader throws', () => {
+        const expectedError = new Error('the expected error')
+
+        expect(() =>
+          loadConfigFile('test.json', {
+            ...baseDI,
+            readFile: () => {
+              throw expectedError
+            }
+          })
+        ).to.throw(Error, expectedError.message)
+      })
+    })
+
+    describe('.cjs', () => {
+      it('throws an error if the CJS file is empty', () => {
+        const { readJs: _readJs, ...di } = baseDI
+        // Note: allowing require to access the file will only work on one test in the entire test suite due to NodeJS global module caching.
+        expect(() =>
+          loadConfigFile('../test/fixtures/config/blank.cjs', di)
+        ).to.throw(
+          ConfigParsingError,
+          /does not export a c8 configuration object/
+        )
+      })
+
+      it('throws the error given by require if the CJS file is invalid Common JS', () => {
+        expect(() =>
+          loadConfigFile('test.cjs', {
+            ...baseDI,
+            readJs: () => {
+              throw new Error('invalid CJS test')
+            }
+          })
+        ).to.throw(Error, 'invalid CJS test')
+      })
+
+      it('returns an empty config if the CJS file exports an empty object', () => {
+        expect(
+          loadConfigFile('test.cjs', {
+            ...baseDI,
+            readJs: () => ({}) // require('./test.cjs') returns {} when the file contains module.exports = {}
+          })
+        ).to.deep.equal({})
+      })
+    })
+
+    describe('.js', () => {
+      it('returns an empty config if the JS file is empty', () => {
+        const { readJs: _readJs, ...di } = baseDI
+        // Note: allowing require to access the file will only work on one test in the entire test suite due to NodeJS global module caching.
+        expect(() =>
+          loadConfigFile('../test/fixtures/config/blank.js', di)
+        ).to.throw(
+          ConfigParsingError,
+          /does not export a c8 configuration object/
+        )
+      })
+
+      it('throws the error given by require if the JS file is invalid Common JS', () => {
+        expect(() =>
+          loadConfigFile('test.js', {
+            ...baseDI,
+            readJs: () => {
+              throw new Error('invalid JS test')
+            }
+          })
+        ).to.throw(Error, 'invalid JS test')
+      })
+
+      it('returns an empty config if the JS file exports an empty object', () => {
+        expect(
+          loadConfigFile('test.js', {
+            ...baseDI,
+            readJs: () => ({}) // require('./test.js') returns {} when the file contains module.exports = {}
+          })
+        ).to.deep.equal({})
+      })
+    })
+
+    for (const ext of ['.yaml', '.yml']) {
+      describe(ext, () => {
+        it('throws an error if the YAML file is empty', () => {
+          expect(() =>
+            loadConfigFile(`test${ext}`, {
+              ...baseDI,
+              readFile: () => ''
+            })
+          ).to.throw(ConfigParsingError, /invalid configuration/i)
+        })
+
+        it('throws an error if the YAML file is invalid', () => {
+          expect(() =>
+            loadConfigFile(`test${ext}`, {
+              ...baseDI,
+              readFile: () => '%not valid'
+            })
+          ).to.throw(
+            ConfigParsingError,
+            /must contain a valid c8 configuration object/i
+          )
+        })
+
+        it('throws the expected error if the file reader throws', () => {
+          const expectedError = new Error('the expected error')
+
+          expect(() =>
+            loadConfigFile(`test${ext}`, {
+              ...baseDI,
+              readFile: () => {
+                throw expectedError
+              }
+            })
+          ).to.throw(Error, expectedError.message)
+        })
+      })
+    }
+  })
+})
diff --git a/test/parse-args.js b/test/parse-args.js
index fa2d5267..ae441ea6 100644
--- a/test/parse-args.js
+++ b/test/parse-args.js
@@ -1,12 +1,17 @@
 /* global describe, it */
 
+const { resolve, join } = require('path')
+const chaiJestSnapshot = require('chai-jest-snapshot')
+
 const {
   buildYargs,
   hideInstrumenteeArgs,
   hideInstrumenterArgs
 } = require('../lib/parse-args')
 
-const { join, resolve } = require('path')
+require('chai')
+  .use(chaiJestSnapshot)
+  .should()
 
 describe('parse-args', () => {
   describe('hideInstrumenteeArgs', () => {
@@ -15,6 +20,12 @@ describe('parse-args', () => {
       const instrumenterArgs = hideInstrumenteeArgs()
       instrumenterArgs.should.eql(['--foo=99', 'my-app'])
     })
+
+    it('test early exit from function if no arguments are passed', () => {
+      process.argv = []
+      const instrumenterArgs = hideInstrumenteeArgs()
+      instrumenterArgs.length.should.eql(0)
+    })
   })
 
   describe('hideInstrumenterArgs', () => {
@@ -25,6 +36,14 @@ describe('parse-args', () => {
       instrumenteeArgs.should.eql(['my-app', '--help'])
       argv.tempDirectory.endsWith(join('coverage', 'tmp')).should.be.equal(true)
     })
+
+    it('interprets first args after -- as Node.js execArgv', async () => {
+      const expected = [process.execPath, '--expose-gc', 'index.js']
+      process.argv = ['node', 'c8', '--', '--expose-gc', 'index.js']
+      const argv = buildYargs().parse(hideInstrumenteeArgs())
+      const munged = hideInstrumenterArgs(argv)
+      munged.should.deep.equal(expected)
+    })
   })
 
   describe('with NODE_V8_COVERAGE already set', () => {
@@ -47,11 +66,19 @@ describe('parse-args', () => {
       const argv = buildYargs().parse(['node', 'c8', '--config', require.resolve('./fixtures/config/.c8rc.json')])
       argv.lines.should.be.equal(101)
       argv.tempDirectory.should.be.equal('./foo')
+      argv.functions.should.be.equal(24)
+    })
+    it('should use config file specified in --config even if it is not a known file name', () => {
+      const argv = buildYargs().parse(['node', 'c8', '--config', require.resolve('./fixtures/config/nonstandard.json')])
+      argv.lines.should.be.equal(420)
+      argv.tempDirectory.should.be.equal('./foo')
+      argv.functions.should.be.equal(24)
     })
     it('should have -c as an alias', () => {
       const argv = buildYargs().parse(['node', 'c8', '-c', require.resolve('./fixtures/config/.c8rc.json')])
       argv.lines.should.be.equal(101)
       argv.tempDirectory.should.be.equal('./foo')
+      argv.functions.should.be.equal(24)
     })
     it('should respect options on the command line over config file', () => {
       const argv = buildYargs().parse(['node', 'c8', '--lines', '100', '--config', require.resolve('./fixtures/config/.c8rc.json')])