Remove ast.json files and skip tests when explain: false in metadata

- Remove all 6823 ast.json files from testdata directories
- Add Explain *bool field to testMetadata struct (pointer to distinguish
  between missing and explicit false)
- Skip tests when explain is explicitly false in metadata
- Add CLAUDE.md with test timeout guidance

Author: claude

parser/CLAUDE.md

@@ -0,0 +1,11 @@
+# Parser Development Notes
+
+## Running Tests
+
+Always run parser tests with a 5 second timeout:
+
+```bash
+go test ./parser/... -timeout 5s
+```
+
+The tests are very fast. If a test is timing out, it indicates a bug (likely an infinite loop in the parser).

parser/parser_test.go

@@ -14,34 +14,17 @@ import (
 
 // testMetadata holds optional metadata for a test case
 type testMetadata struct {
-	Todo   bool   `json:"todo,omitempty"`
-	Source string `json:"source,omitempty"`
-}
-
-// astJSON represents the structure of ast.json from ClickHouse EXPLAIN AST
-type astJSON struct {
-	Meta []struct {
-		Name string `json:"name"`
-		Type string `json:"type"`
-	} `json:"meta"`
-	Data []struct {
-		Explain string `json:"explain"`
-	} `json:"data"`
-	Rows       int `json:"rows"`
-	Statistics struct {
-		Elapsed  float64 `json:"elapsed"`
-		RowsRead int     `json:"rows_read"`
-		BytesRead int    `json:"bytes_read"`
-	} `json:"statistics"`
-	Error bool `json:"error,omitempty"`
+	Todo    bool   `json:"todo,omitempty"`
+	Source  string `json:"source,omitempty"`
+	Explain *bool  `json:"explain,omitempty"`
 }
 
 // TestParser tests the parser using test cases from the testdata directory.
 // Each subdirectory in testdata represents a test case with:
 // - query.sql: The SQL query to parse
-// - ast.json: Expected AST from ClickHouse EXPLAIN AST
 // - metadata.json (optional): Metadata including:
 //   - todo: true if the test is not yet expected to pass
+//   - explain: false to skip the test (e.g., when ClickHouse couldn't parse it)
 func TestParser(t *testing.T) {
 	testdataDir := "testdata"
 
@@ -64,13 +47,13 @@ func TestParser(t *testing.T) {
 			ctx, cancel := context.WithTimeout(context.Background(), 1*time.Second)
 			defer cancel()
 
-			// Read the query (only first line, as ast.json was generated from first statement)
+			// Read the query (only first line)
 			queryPath := filepath.Join(testDir, "query.sql")
 			queryBytes, err := os.ReadFile(queryPath)
 			if err != nil {
 				t.Fatalf("Failed to read query.sql: %v", err)
 			}
-			// Get first line only (ast.json contains AST for first statement)
+			// Get first line only
 			lines := strings.SplitN(string(queryBytes), "\n", 2)
 			query := strings.TrimSpace(lines[0])
 
@@ -83,18 +66,9 @@ func TestParser(t *testing.T) {
 				}
 			}
 
-			// Read expected AST from ClickHouse
-			var expectedAST astJSON
-			astPath := filepath.Join(testDir, "ast.json")
-			if astBytes, err := os.ReadFile(astPath); err == nil {
-				if err := json.Unmarshal(astBytes, &expectedAST); err != nil {
-					t.Fatalf("Failed to parse ast.json: %v", err)
-				}
-			}
-
-			// Skip tests where ClickHouse also couldn't parse the query
-			if expectedAST.Error {
-				t.Skipf("ClickHouse also failed to parse this query")
+			// Skip tests where explain is explicitly false (e.g., ClickHouse couldn't parse it)
+			if metadata.Explain != nil && !*metadata.Explain {
+				t.Skipf("Skipping: explain is false in metadata")
 				return
 			}
 
@@ -125,8 +99,6 @@ func TestParser(t *testing.T) {
 				}
 				t.Fatalf("JSON marshal error: %v\nQuery: %s", jsonErr, query)
 			}
-
-			// TODO: Compare parsed AST against expectedAST.Data
 		})
 	}
 }