acc: Fix schemas CRUD and add test for schema deployment (#2664)

## Changes
- Fix testserver's schemas CRUD to merge PATCH requests properly.
- Add an acceptance test for modifying schema resource.
- Add a script to read selected state from terraform in tests.

## Why
This test helps validate testserver. I'm also using it in terraform
removal branch to validate my prototype.

## Tests
Existing tests.

Author: denik

acceptance/bin/read_state.py

@@ -0,0 +1,38 @@
+#!/usr/bin/env python3
+"""
+Print selected attributes from terraform state.
+
+Usage: <section> <name> [attr...]
+"""
+
+import sys
+import os
+import json
+
+
+def print_resource_terraform(section, name, *attrs):
+    resource_type = "databricks_" + section[:-1]
+    filename = ".databricks/bundle/default/terraform/terraform.tfstate"
+    data = json.load(open(filename))
+    available = []
+    found = 0
+    for r in data["resources"]:
+        r_type = r["type"]
+        r_name = r["name"]
+        if r_type != resource_type:
+            available.append((r_type, r_name))
+            continue
+        if r_name != name:
+            available.append((r_type, r_name))
+            continue
+        for inst in r["instances"]:
+            attribute_values = inst.get("attributes")
+            if attribute_values:
+                values = [f"{x}={attribute_values.get(x)!r}" for x in attrs]
+                print(section, name, " ".join(values))
+                found += 1
+    if not found:
+        print(f"Resource {(resource_type, name)} not found. Available: {available}")
+
+
+print_resource_terraform(*sys.argv[1:])

acceptance/bundle/resources/schemas/databricks.yml

@@ -0,0 +1,9 @@
+bundle:
+  name: schema-test
+
+resources:
+  schemas:
+    schema1:
+      name: myschema
+      catalog_name: main
+      comment: COMMENT1

acceptance/bundle/resources/schemas/output.txt

@@ -0,0 +1,56 @@
+
+>>> [CLI] bundle deploy
+Uploading bundle files to /Workspace/Users/[USERNAME]/.bundle/schema-test/default/files...
+Deploying resources...
+Updating deployment state...
+Deployment complete!
+
+>>> print_requests
+{
+  "method": "POST",
+  "path": "/api/2.1/unity-catalog/schemas",
+  "body": {
+    "catalog_name": "main",
+    "comment": "COMMENT1",
+    "name": "myschema"
+  }
+}
+schemas schema1 id='main.myschema' name='myschema' catalog_name='main' comment='COMMENT1'
+
+=== Update comment and re-deploy
+>>> update_file.py databricks.yml COMMENT1 COMMENT2
+
+>>> [CLI] bundle deploy
+Uploading bundle files to /Workspace/Users/[USERNAME]/.bundle/schema-test/default/files...
+Deploying resources...
+Updating deployment state...
+Deployment complete!
+
+>>> print_requests
+{
+  "method": "PATCH",
+  "path": "/api/2.1/unity-catalog/schemas/main.myschema",
+  "body": {
+    "comment": "COMMENT2"
+  }
+}
+schemas schema1 id='main.myschema' name='myschema' catalog_name='main' comment='COMMENT2'
+
+=== Restore comment to original value and re-deploy
+>>> update_file.py databricks.yml COMMENT2 COMMENT1
+
+>>> [CLI] bundle deploy
+Uploading bundle files to /Workspace/Users/[USERNAME]/.bundle/schema-test/default/files...
+Deploying resources...
+Updating deployment state...
+Deployment complete!
+
+>>> print_requests
+{
+  "method": "PATCH",
+  "path": "/api/2.1/unity-catalog/schemas/main.myschema",
+  "body": {
+    "comment": "COMMENT1"
+  }
+}
+schemas schema1 id='main.myschema' name='myschema' catalog_name='main' comment='COMMENT1'

acceptance/bundle/resources/schemas/script

@@ -0,0 +1,22 @@
+echo "*" > .gitignore
+trace $CLI bundle deploy
+
+print_requests() {
+    jq 'select(.method != "GET" and (.path | contains("/unity")))' < out.requests.txt
+    rm out.requests.txt
+}
+
+trace print_requests
+read_state.py schemas schema1 id name catalog_name comment
+
+title "Update comment and re-deploy"
+trace update_file.py databricks.yml COMMENT1 COMMENT2
+trace $CLI bundle deploy
+trace print_requests
+read_state.py schemas schema1 id name catalog_name comment
+
+title "Restore comment to original value and re-deploy"
+trace update_file.py databricks.yml COMMENT2 COMMENT1
+trace $CLI bundle deploy
+trace print_requests
+read_state.py schemas schema1 id name catalog_name comment

acceptance/bundle/resources/schemas/test.toml

@@ -0,0 +1 @@
+RecordRequests = true

libs/testserver/schemas.go

@@ -43,7 +43,7 @@ func (s *FakeWorkspace) SchemasUpdate(req Request, name string) Response {
 		}
 	}
 
-	err := mergo.Merge(&existing, schemaUpdate)
+	err := mergo.Merge(&existing, schemaUpdate, mergo.WithOverride)
 	if err != nil {
 		return Response{
 			Body:       fmt.Sprintf("mergo error: %s", err),