feature: Expand env variables (#391)

Closes #178

docs/configuration.md

@@ -692,6 +692,29 @@ pre-commit:
       run: bundle exec rspec
 ```
 
+#### Extending PATH
+
+If your hook is run by GUI program, and you use some PATH tweaks in your ~/.<shell>rc, you might see an error saying *executable not found*. In that case You can extend the **$PATH** variable with `lefthook-local.yml` configuration the following way.
+
+```yml
+# lefthook.yml
+
+pre-commit:
+  commands:
+    test:
+      run: yarn test
+```
+
+```yml
+# lefthook-local.yml
+
+pre-commit:
+  commands:
+    test:
+      env:
+        PATH: $PATH:/home/me/path/to/yarn
+```
+
 **Notes**
 
 This option is useful when using lefthook on different OSes or shells where ENV variables are set in different ways.

internal/lefthook/runner/execute_unix.go

@@ -41,7 +41,7 @@ func (e CommandExecutor) Execute(opts ExecuteOptions) (*bytes.Buffer, error) {
 	for name, value := range opts.env {
 		envList = append(
 			envList,
-			fmt.Sprintf("%s=%s", strings.ToUpper(name), value),
+			fmt.Sprintf("%s=%s", strings.ToUpper(name), os.ExpandEnv(value)),
 		)
 	}
 

internal/lefthook/runner/execute_windows.go

@@ -25,7 +25,7 @@ func (e CommandExecutor) Execute(opts ExecuteOptions) (*bytes.Buffer, error) {
 	for name, value := range opts.env {
 		envList = append(
 			envList,
-			fmt.Sprintf("%s=%s", strings.ToUpper(name), value),
+			fmt.Sprintf("%s=%s", strings.ToUpper(name), os.ExpandEnv(value)),
 		)
 	}
 

internal/templates/hook.tmpl

@@ -42,6 +42,4 @@ call_lefthook()
   fi
 }
 
-{{.AutoInstall}}
-
 call_lefthook "run {{.HookName}} $@"

internal/templates/templates.go

@@ -14,9 +14,8 @@ const checksumFormat = "%s %d\n"
 var templatesFS embed.FS
 
 type hookTmplData struct {
-	AutoInstall string
-	HookName    string
-	Extension   string
+	HookName  string
+	Extension string
 }
 
 func Hook(hookName string) []byte {