biome: fix silent failures (warnings + .gitignore in sandbox)

linters/biome/biome.test.ts

@@ -1,5 +1,49 @@
-import { linterCheckTest, linterFmtTest } from "tests";
+import { linterCheckTest, linterFmtTest, TestCallback } from "tests";
 
 linterCheckTest({ linterName: "biome", namedTestPrefixes: ["basic_check"] });
 
 linterFmtTest({ linterName: "biome", namedTestPrefixes: ["basic_fmt", "basic_json"] });
+
+// Verify warning-level findings ('!' marker) are captured by parse_regex,
+// not just errors ('×'). Regression coverage for trunk-io/plugins#1113.
+const enableWarnRule: TestCallback = (driver) => {
+  driver.writeFile(
+    "biome.json",
+    JSON.stringify({
+      $schema: "https://biomejs.dev/schemas/2.3.4/schema.json",
+      linter: {
+        enabled: true,
+        rules: {
+          recommended: false,
+          style: { noNonNullAssertion: "warn" },
+        },
+      },
+    }),
+  );
+};
+linterCheckTest({
+  linterName: "biome",
+  namedTestPrefixes: ["warning_check"],
+  preCheck: enableWarnRule,
+});
+
+// Verify .gitignore reaches the sandbox so vcs.useIgnoreFile works. Without
+// the symlinks: directive in plugin.yaml, biome aborts with internalError/fs
+// when it can't find the ignore file and silently drops all findings.
+// Regression coverage for trunk-io/plugins#1113 issue 2.
+const setupGitignoreRepo: TestCallback = (driver) => {
+  driver.writeFile(
+    "biome.json",
+    JSON.stringify({
+      $schema: "https://biomejs.dev/schemas/2.3.4/schema.json",
+      vcs: { clientKind: "git", enabled: true, useIgnoreFile: true },
+      linter: { enabled: true, rules: { recommended: true } },
+    }),
+  );
+  driver.writeFile(".gitignore", "");
+};
+linterCheckTest({
+  linterName: "biome",
+  namedTestPrefixes: ["gitignore_check"],
+  preCheck: setupGitignoreRepo,
+});

linters/biome/plugin.yaml

@@ -22,9 +22,15 @@ lint:
       commands:
         - name: lint
           output: regex
+          # Match both errors (×) and warnings (!). The marker line must be
+          # the immediate next line (after a blank line) following the header,
+          # so each diagnostic is parsed as a self-contained block — the prior
+          # regex lazily matched across diagnostics and silently mis-attributed
+          # path/line/col to a different finding's message. Info-level (i) is
+          # intentionally excluded; biome surfaces those for hints, not gating.
           parse_regex:
-            ' *(?P<path>.*?):(?P<line>\d+):(?P<col>\d+) (?P<code>[^ ]+)(?:[^×]*\n).*×
-            (?P<message>.*)\n'
+            ' *(?P<path>[^\n]*?):(?P<line>\d+):(?P<col>\d+) (?P<code>[^ \n]+)[^\n]*\n[ \t]*\n[
+            \t]+[×!] (?P<message>[^\n]+)'
           run: biome check ${target}
           success_codes: [0, 1]
           batch: true
@@ -51,3 +57,10 @@ lint:
       version_command:
         parse_regex: biome CLI version ${semver}
         run: biome --version
+      symlinks:
+        # biome's vcs.useIgnoreFile reads .gitignore from the sandbox root.
+        # Without this, the per-target sandbox lacks .gitignore and biome
+        # aborts with internalError/fs, silently dropping all findings.
+        # See trunk-io/plugins#1113.
+        - from: ${workspace}/.gitignore
+          to: .gitignore

linters/biome/test_data/biome_v2.3.4_basic_check.check.shot

@@ -4,14 +4,14 @@ exports[`Testing linter biome test basic_check 1`] = `
 {
   "issues": [
     {
-      "code": "lint/complexity/noUselessLoneBlockStatements",
-      "column": "3",
+      "code": "lint/correctness/noUnusedVariables",
+      "column": "7",
       "file": "test_data/basic_check.in.ts",
       "issueClass": "ISSUE_CLASS_EXISTING",
       "level": "LEVEL_HIGH",
-      "line": "13",
+      "line": "6",
       "linter": "biome",
-      "message": "Formatter would have printed the following content:",
+      "message": "This variable foo is unused.",
       "targetType": "typescript",
     },
   ],

linters/biome/test_data/biome_v2.3.4_gitignore_check.check.shot

@@ -0,0 +1,51 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Testing linter biome test gitignore_check 1`] = `
+{
+  "issues": [
+    {
+      "code": "lint/correctness/noUnusedVariables",
+      "column": "7",
+      "file": "test_data/gitignore_check.in.ts",
+      "issueClass": "ISSUE_CLASS_EXISTING",
+      "level": "LEVEL_HIGH",
+      "line": "1",
+      "linter": "biome",
+      "message": "This variable unusedHelper is unused.",
+      "targetType": "typescript",
+    },
+  ],
+  "lintActions": [
+    {
+      "command": "fmt",
+      "fileGroupName": "typescript",
+      "linter": "biome",
+      "paths": [
+        "test_data/gitignore_check.in.ts",
+      ],
+      "verb": "TRUNK_VERB_FMT",
+    },
+    {
+      "command": "lint",
+      "fileGroupName": "typescript",
+      "linter": "biome",
+      "paths": [
+        "test_data/gitignore_check.in.ts",
+      ],
+      "verb": "TRUNK_VERB_CHECK",
+    },
+    {
+      "command": "lint",
+      "fileGroupName": "typescript",
+      "linter": "biome",
+      "paths": [
+        "test_data/gitignore_check.in.ts",
+      ],
+      "upstream": true,
+      "verb": "TRUNK_VERB_CHECK",
+    },
+  ],
+  "taskFailures": [],
+  "unformattedFiles": [],
+}
+`;

linters/biome/test_data/biome_v2.3.4_warning_check.check.shot

@@ -0,0 +1,51 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Testing linter biome test warning_check 1`] = `
+{
+  "issues": [
+    {
+      "code": "lint/style/noNonNullAssertion",
+      "column": "16",
+      "file": "test_data/warning_check.in.ts",
+      "issueClass": "ISSUE_CLASS_EXISTING",
+      "level": "LEVEL_HIGH",
+      "line": "5",
+      "linter": "biome",
+      "message": "Forbidden non-null assertion.",
+      "targetType": "typescript",
+    },
+  ],
+  "lintActions": [
+    {
+      "command": "fmt",
+      "fileGroupName": "typescript",
+      "linter": "biome",
+      "paths": [
+        "test_data/warning_check.in.ts",
+      ],
+      "verb": "TRUNK_VERB_FMT",
+    },
+    {
+      "command": "lint",
+      "fileGroupName": "typescript",
+      "linter": "biome",
+      "paths": [
+        "test_data/warning_check.in.ts",
+      ],
+      "verb": "TRUNK_VERB_CHECK",
+    },
+    {
+      "command": "lint",
+      "fileGroupName": "typescript",
+      "linter": "biome",
+      "paths": [
+        "test_data/warning_check.in.ts",
+      ],
+      "upstream": true,
+      "verb": "TRUNK_VERB_CHECK",
+    },
+  ],
+  "taskFailures": [],
+  "unformattedFiles": [],
+}
+`;

linters/biome/test_data/gitignore_check.in.ts

@@ -0,0 +1,2 @@
+const unusedHelper = (input: number) => input + 1;
+export const sample = 42;

linters/biome/test_data/warning_check.in.ts

@@ -0,0 +1,6 @@
+// Triggers biome's lint/style/noNonNullAssertion at warning level when the
+// rule is enabled with `level: "warn"`. Verifies that the lint parse_regex
+// captures '!' (warning marker) findings, not just '×' (error marker).
+const value: number | null = null;
+const result = value!.toFixed();
+console.log(result);