Improve error messages for external config files

__tests__/config.test.ts

@@ -113,7 +113,7 @@ test('it reads an external config file', async () => {
 
 test('raises an error when the the config file was not found', async () => {
   setInput('config-file', 'fixtures/i-dont-exist')
-  await expect(readConfig()).rejects.toThrow(/Unable to fetch config file/)
+  await expect(readConfig()).rejects.toThrow(/Unable to fetch/)
 })
 
 test('it parses options from both sources', async () => {
@@ -232,6 +232,16 @@ test('it is not possible to disable both checks', async () => {
   )
 })
 
+test('it supports comma-separated lists', async () => {
+  setInput(
+    'config-file',
+    './__tests__/fixtures/inline-license-config-sample.yml'
+  )
+  let config = await readConfig()
+
+  expect(config.allow_licenses).toEqual(['MIT', 'GPL-2.0-only'])
+})
+
 describe('licenses that are not valid SPDX licenses', () => {
   beforeAll(() => {
     jest.spyOn(Utils, 'isSPDXValid').mockReturnValue(false)
@@ -240,14 +250,14 @@ describe('licenses that are not valid SPDX licenses', () => {
   test('it raises an error for invalid licenses in allow-licenses', async () => {
     setInput('allow-licenses', ' BSD, GPL 2')
     await expect(readConfig()).rejects.toThrow(
-      'Invalid license(s) in allow-licenses: BSD, GPL 2'
+      'Invalid license(s) in allow-licenses: BSD,GPL 2'
     )
   })
 
   test('it raises an error for invalid licenses in deny-licenses', async () => {
     setInput('deny-licenses', ' BSD, GPL 2')
     await expect(readConfig()).rejects.toThrow(
-      'Invalid license(s) in deny-licenses: BSD, GPL 2'
+      'Invalid license(s) in deny-licenses: BSD,GPL 2'
     )
   })
 })

__tests__/fixtures/inline-license-config-sample.yml

@@ -0,0 +1 @@
+allow-licenses: MIT, GPL-2.0-only

src/config.ts

@@ -80,12 +80,11 @@ function validateLicenses(
   if (licenses === undefined) {
     return
   }
+
   const invalid_licenses = licenses.filter(license => !isSPDXValid(license))
 
   if (invalid_licenses.length > 0) {
-    throw new Error(
-      `Invalid license(s) in ${key}: ${invalid_licenses.join(', ')}`
-    )
+    throw new Error(`Invalid license(s) in ${key}: ${invalid_licenses}`)
   }
 }
 
@@ -113,18 +112,41 @@ async function readConfigFile(
     }
     return parseConfigFile(data)
   } catch (error) {
-    core.debug(error as string)
-    throw new Error('Unable to fetch config file')
+    throw new Error(
+      `Unable to fetch or parse config file: ${(error as Error).message}`
+    )
   }
 }
 
 function parseConfigFile(configData: string): ConfigurationOptionsPartial {
   try {
     const data = YAML.parse(configData)
+
+    // These are the options that we support where the user can provide
+    // either a YAML list or a comma-separated string.
+    const listKeys = [
+      'allow-licenses',
+      'deny-licenses',
+      'fail-on-scopes',
+      'allow-ghsas'
+    ]
+
     for (const key of Object.keys(data)) {
+      // strings can contain list values (e.g. 'MIT, Apache-2.0'). In this
+      // case we need to parse that into a list (e.g. ['MIT', 'Apache-2.0']).
+      if (listKeys.includes(key)) {
+        const val = data[key]
+
+        if (typeof val === 'string') {
+          data[key] = val.split(',').map(x => x.trim())
+        }
+      }
+
+      // perform SPDX validation
       if (key === 'allow-licenses' || key === 'deny-licenses') {
         validateLicenses(key, data[key])
       }
+
       // get rid of the ugly dashes from the actions conventions
       if (key.includes('-')) {
         data[key.replace(/-/g, '_')] = data[key]