New pattern to update module

.grit/patterns/edit_module.md

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+---
+title: Edit module
+---
+
+Update a module by specifying its old `source` and the new one.
+
+It will update the `source` attribute of the modules and remove all variables that
+are not found on another module `path`.
+
+```grit
+engine marzano(0.1)
+language hcl
+
+pattern fix_module($old_source, $new_source, $allow_variables) {
+    `module $_ {
+        $args
+    }` where {
+        // Make sure we're looking at a module with $old_source
+        $args <: contains `source = $old_source` => `source = $new_source`,
+        // Check all attributes
+        $args <: maybe contains bubble($allow_variables) `$key = $value` as $attr where {
+            $key <: or {
+                // Remap some keys
+                `identifier` => `db_identifier`,
+                // Keep source
+                `source`,
+                // Keep meta-arguments
+                `count`,
+                `depends_on`,
+                `for_each`,
+                `lifecycle`,
+                `provider`,
+                $_ where {
+                    $allow_variables <: some bubble($key) $candidate where { $candidate <: $key }
+                },
+                // Finally, delete others we don't recognize
+                $_ where { $attr => .}
+            }
+
+            // Remove others
+            // or {
+            //     `version = $_`,
+            //     `storage_encrypted = $_`,
+            //     `apply_immediately = $_`
+            // } => .
+        } until attribute()
+    }
+}
+
+pattern collect_variables($var_names) {
+    `variable $name {
+        $_
+    }` where {
+        $name <: string_lit($content),
+        if ($var_names <: undefined) {
+            $var_names = []
+        },
+        $var_names += $content,
+    }
+}
+
+pattern edit_module($old_source, $new_source, $module_path) {
+    $var_names = [],
+    some bubble($var_names) file($name, $body) where {
+      $name <: r"\./variables/.*", // Path to get variables from
+      $body <: contains collect_variables($var_names),
+    },
+    some bubble($old_source, $new_source, $var_names) file($name, $body) where {
+        $body <: contains fix_module($old_source, $new_source, allow_variables=$var_names)
+    }
+}
+
+files(files = edit_module(old_source=`"old_source"`, new_source=`"new_source"`, module_path=""))
+```

.grit/patterns/test_edit_module/expected/main.tf

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+module "test_module1" {
+  source = "new_source"
+  variable1 = "variable1"
+  variable2 = "variable2"
+
+
+}
+
+module "test_module2" {
+  source = "new_source"
+  variable1 = "variable1"
+  variable2 = "variable2"
+
+
+}
+
+module "test_module3" {
+  source    = "another_source"
+  variable1 = "variable1"
+  variable2 = "variable2"
+  variable3 = "variable3"
+  variable4 = "variable4"
+}

.grit/patterns/test_edit_module/input/main.tf

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+module "test_module1" {
+  source    = "old_source"
+  variable1 = "variable1"
+  variable2 = "variable2"
+  variable3 = "variable3"
+  variable4 = "variable4"
+}
+
+module "test_module2" {
+  source    = "old_source"
+  variable1 = "variable1"
+  variable2 = "variable2"
+  variable3 = "variable3"
+  variable4 = "variable4"
+}
+
+module "test_module3" {
+  source    = "another_source"
+  variable1 = "variable1"
+  variable2 = "variable2"
+  variable3 = "variable3"
+  variable4 = "variable4"
+}

.grit/patterns/test_edit_module/test.sh

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+#!/bin/bash
+
+# test.sh should be run from the current directory: hcl/.grit/patterns/test_edit_module
+
+set -e
+cp input/main.tf input/main.tf.bak                      # 1. Backup input.tf
+grit apply ../edit_module.md --force --suppress-output  # 2. Apply pattern
+diff input/main.tf expected/main.tf                     # 3. Check that the modified input.tf equals expect.tf
+mv input/main.tf.bak input/main.tf                      # 4. Restore input.tf from the backup
+echo "Test successful"

.grit/patterns/test_edit_module/variables/variables.tf

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+variable "variable1" {}
+variable "variable2" {
+  description = "description"
+}

.grit/patterns/test_edit_module/variables_not_to_use/variables.tf

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+variable "variable3" {}
+variable "variable4" {
+  description = "description"
+}