Parse the config input once

Co-authored-by: Copilot App <223556219+Copilot@users.noreply.github.com>

src/config/db-config.test.ts

@@ -626,6 +626,16 @@ test("mergeDefaultSetupAndUserConfigs - warns about invalid keys from Default Se
   ]);
 });
 
+/** Parses `contents` as a configuration without validating it. */
+function parseUnvalidatedConfig(contents: string): dbConfig.UserConfig {
+  return dbConfig.parseUserConfig(
+    getRunnerLogger(true),
+    "test",
+    contents,
+    false,
+  );
+}
+
 test("matchesDefaultSetupConfigSchema - returns true for configurations that only use Default Setup properties", (t) => {
   for (const contents of [
     [
@@ -637,7 +647,12 @@ test("matchesDefaultSetupConfigSchema - returns true for configurations that onl
     "threat-models: [ local ]",
     "{}",
   ]) {
-    t.true(dbConfig.matchesDefaultSetupConfigSchema(contents), contents);
+    t.true(
+      dbConfig.matchesDefaultSetupConfigSchema(
+        parseUnvalidatedConfig(contents),
+      ),
+      contents,
+    );
   }
 });
 
@@ -647,7 +662,12 @@ test("matchesDefaultSetupConfigSchema - returns false for configurations that us
     "paths-ignore: [ tests ]",
     "default-setup: { org: { model-packs: [], queries: [] } }",
   ]) {
-    t.false(dbConfig.matchesDefaultSetupConfigSchema(contents), contents);
+    t.false(
+      dbConfig.matchesDefaultSetupConfigSchema(
+        parseUnvalidatedConfig(contents),
+      ),
+      contents,
+    );
   }
 });
 
@@ -656,12 +676,22 @@ test("matchesDefaultSetupConfigSchema - returns false for invalid Default Setup
     "threat-models: local",
     "default-setup: { org: { model-packs: [ 1 ] } }",
   ]) {
-    t.false(dbConfig.matchesDefaultSetupConfigSchema(contents), contents);
+    t.false(
+      dbConfig.matchesDefaultSetupConfigSchema(
+        parseUnvalidatedConfig(contents),
+      ),
+      contents,
+    );
   }
 });
 
-test("matchesDefaultSetupConfigSchema - returns false for contents that aren't a YAML object", (t) => {
-  for (const contents of ["threat-models: [", "- threat-models", "local", ""]) {
-    t.false(dbConfig.matchesDefaultSetupConfigSchema(contents), contents);
+test("matchesDefaultSetupConfigSchema - returns false for configurations that aren't mappings", (t) => {
+  for (const contents of ["- threat-models", "local", "null"]) {
+    t.false(
+      dbConfig.matchesDefaultSetupConfigSchema(
+        parseUnvalidatedConfig(contents),
+      ),
+      contents,
+    );
   }
 });

src/config/db-config.ts

@@ -106,24 +106,16 @@ function checkDefaultSetupConfig(
 }
 
 /**
- * Returns whether `contents` is a YAML mapping that only sets the properties that Default Setup
- * uses, which are threat models and model packs, to valid values. Returns `false` otherwise,
- * including if `contents` isn't valid YAML.
+ * Returns whether `config` is a mapping that only sets the properties that Default Setup sets in
+ * the `config` input, to valid values.
  */
-export function matchesDefaultSetupConfigSchema(contents: string): boolean {
-  let config: unknown;
-  try {
-    config = yaml.load(contents);
-  } catch (error) {
-    if (error instanceof yaml.YAMLException) {
-      return false;
-    }
-    throw error;
-  }
+export function matchesDefaultSetupConfigSchema(config: UserConfig): boolean {
+  // Unless validation is enabled, `parseUserConfig` doesn't check that the YAML is a mapping.
   if (!json.isObject(config)) {
     return false;
   }
-  const result = checkDefaultSetupConfig(config);
+  const result = checkDefaultSetupConfig(config as json.UnvalidatedObject<any>);
+  // `valid` doesn't account for unknown properties.
   return result.valid && result.unknownKeys.length === 0;
 }