feat(sam): filter known sam cli errors

The sam cli may fail when executing operations
internally. An example is trying to debug a
lambda using python, but a specific python
version does not exist.

This commit now has the sam cli invoker collect
accepted errors (based off certain prefixes)
and throws them instead of indicating
'no message available'

You can test this by:
- Running the 'Extenstion' debugger
- Creating a python3.7 SAM lambda application
- Run and debug the lambda function
- An error message window will appear
  telling you it could not find the python3.7
  runtime (assuming you don't have it locally)

Signed-off-by: Nikolas Komonen <[email protected]>

Author: nkomonen-amazon

src/shared/sam/cli/samCliInvokerUtils.ts

@@ -55,6 +55,42 @@ export function logAndThrowIfUnexpectedExitCode(processResult: ChildProcessResul
             message = processResult.error.message
         }
     }
+    const usefulErrors = collectAcceptedErrorMessages(processResult.stderr).join('\n')
+    throw makeUnexpectedExitCodeError(message ?? usefulErrors)
+}
+
+/**
+ * Collect known errors messages from a sam error message
+ * that may have multiple errors in one message.
+ * @param errors A string that can have multiple error messages
+ */
+export function collectAcceptedErrorMessages(errorMessage: string): string[] {
+    const errors = errorMessage.split('\n')
+    const shouldCollectFuncs = [_startsWithEscapeSequence, _startsWithError]
+    return errors.filter(error => {
+        return shouldCollectFuncs.some(shouldCollect => {
+            return shouldCollect(error)
+        })
+    })
+}
+
+/**
+ * Returns true if text starts with an escape
+ * sequence with one of the accepted sequences.
+ */
+function _startsWithEscapeSequence(text: string): boolean {
+    const escapeInDecimal = 27
+    if (text.charCodeAt(0) !== escapeInDecimal) {
+        return false
+    }
+
+    const remainingText = text.substring(1)
+    const acceptedSequences = ['[33m']
+    return acceptedSequences.some(code => {
+        return remainingText.startsWith(code)
+    })
+}
 
-    throw makeUnexpectedExitCodeError(message ?? 'no message available')
+function _startsWithError(text: string): boolean {
+    return text.startsWith('Error:')
 }

src/test/shared/sam/cli/samCliInvokerUtils.test.ts

@@ -5,6 +5,7 @@
 
 import * as assert from 'assert'
 import {
+    collectAcceptedErrorMessages,
     logAndThrowIfUnexpectedExitCode,
     makeUnexpectedExitCodeError,
 } from '../../../../shared/sam/cli/samCliInvokerUtils'
@@ -42,3 +43,41 @@ describe('logAndThrowIfUnexpectedExitCode', async function () {
         await assertLogContainsBadExitInformation(getTestLogger(), childProcessResult, 456)
     })
 })
+
+/**
+ * Returns a string with the 'Escape' character
+ * prepended to the given text.
+ *
+ * This exists because using '\e' does not
+ * work.
+ */
+function prependEscapeCode(text: string): string {
+    return String.fromCharCode(27) + text
+}
+
+describe('collectAcceptedErrorMessages()', async () => {
+    let result: string[]
+
+    before(async () => {
+        const input = [
+            prependEscapeCode('[33m This is an accepted escape sequence'),
+            prependEscapeCode('[100m This is not an accepted escape sequence'),
+            'This will be ignored',
+            'Error: This is accepted due to the prefix',
+        ].join('\n')
+        result = collectAcceptedErrorMessages(input)
+    })
+
+    it('has the expected amount of messages', async () => {
+        assert.strictEqual(result.length, 2)
+    })
+    it('collects the "Error:" prefix', async () => {
+        assert(result.includes('Error: This is accepted due to the prefix'))
+    })
+    it('collects accepted escape sequence prefixes', async () => {
+        assert(result.includes(prependEscapeCode('[33m This is an accepted escape sequence')))
+    })
+    it('ignores non-accepted escape sequence prefixes', async () => {
+        assert(!result.includes(prependEscapeCode('[100m This is not an accepted escape sequence')))
+    })
+})