use empty string to "unset" variables

the memento[1] and environment variable collection[2] apis
don't support "unsetting" variables,
only deleting them from the collection,
which leads to those variables being left along.
this change uses the empty string instead.
posix calls this value "null" for environment variables,
and it's technically different from the variable being unset
but the closest we can get.

[1]: https://code.visualstudio.com/api/references/vscode-api#Memento
[2]: https://code.visualstudio.com/api/references/vscode-api#EnvironmentVariableCollection

CHANGELOG.md

@@ -7,6 +7,10 @@ Check [Keep a Changelog](http://keepachangelog.com/) for recommendations on how
 ## [Unreleased]
 ### Changed
 - Require VSCode 1.66
+- "Unset" variables by setting them to the empty string
+### Fixed
+- Avoid continuously asking to restart
+	If this keeps happening to you, please let us know!
 
 ## [0.6.1] - 2022-03-25
 ### Fixed

src/extension.ts

@@ -112,7 +112,7 @@ class Direnv implements vscode.Disposable {
 		await this.cache.update(
 			Cached.environment,
 			Object.fromEntries(
-				[...this.backup.entries()].map(([key]) => [key, process.env[key]]),
+				[...this.backup.entries()].map(([key]) => [key, process.env[key] ?? '']),
 			),
 		)
 	}
@@ -124,13 +124,9 @@ class Direnv implements vscode.Disposable {
 				this.backup.set(key, process.env[key])
 			}
 
-			if (value !== null) {
-				process.env[key] = value
-				this.environment.replace(key, value)
-			} else {
-				delete process.env[key]
-				this.environment.delete(key) // can't unset the variable
-			}
+			value ??= '' // can't unset, set to empty instead
+			process.env[key] = value
+			this.environment.replace(key, value)
 		})
 	}
 

src/test/runTest.ts

@@ -6,10 +6,11 @@ async function main() {
 	try {
 		const extensionDevelopmentPath = path.resolve(__dirname, '../../')
 		const extensionTestsPath = path.resolve(__dirname, './suite/index')
+		const extensionTestsEnv = { ['PREDEFINED']: 'value' }
 		const workspacePath = path.resolve(__dirname, '../../test/workspace')
 		const disableExtensions = '--disable-extensions'
 		const launchArgs = [workspacePath, disableExtensions]
-		await runTests({ extensionDevelopmentPath, extensionTestsPath, launchArgs })
+		await runTests({ extensionDevelopmentPath, extensionTestsPath, extensionTestsEnv, launchArgs })
 	} catch (err) {
 		console.error('Failed to run tests')
 		process.exit(1)

test/workspace/.envrc

@@ -1,2 +1,3 @@
 # shellcheck shell=bash
 export VARIABLE=value
+unset PREDEFINED

test/workspace/.vscode/tasks.json

@@ -7,14 +7,14 @@
 			"label": "test-task",
 			"detail": "test that the .envrc environment is available in the task shell",
 			"type": "shell",
-			"command": "test -n \"$VARIABLE\"",
+			"command": "test -n \"$VARIABLE\" && test -z \"$PREDEFINED\"",
 			"problemMatcher": []
 		},
 		{
 			"label": "test-process",
 			"detail": "test that the .envrc environment is available in process.env",
 			"type": "shell",
-			"command": "test -n \"${env:VARIABLE}\"",
+			"command": "test -n \"${env:VARIABLE}\" && test -z \"${env:PREDEFINED}\"",
 			"problemMatcher": []
 		},
 	]