styx_format/

value_format.rs

//! Format `styx_tree::Value` to Styx text.

use styx_tree::{Entry, Object, Payload, Sequence, Value};

use crate::{FormatOptions, StyxWriter};

/// Format a Value as a Styx document string.
///
/// The value is treated as the root of a document, so if it's an Object,
/// it will be formatted without braces (implicit root object).
pub fn format_value(value: &Value, options: FormatOptions) -> String {
    let mut formatter = ValueFormatter::new(options);
    formatter.format_root(value);
    formatter.finish_document()
}

/// Format a Value as a Styx document string with default options.
pub fn format_value_default(value: &Value) -> String {
    format_value(value, FormatOptions::default())
}

/// Format an Object directly (with braces), not as a root document.
///
/// This is useful for code actions that need to format a single object
/// while respecting its separator style.
pub fn format_object_braced(obj: &Object, options: FormatOptions) -> String {
    let mut formatter = ValueFormatter::new(options);
    formatter.format_object(obj);
    formatter.finish()
}

struct ValueFormatter {
    writer: StyxWriter,
}

impl ValueFormatter {
    fn new(options: FormatOptions) -> Self {
        Self {
            writer: StyxWriter::with_options(options),
        }
    }

    /// Finish and return output without trailing newline.
    fn finish(self) -> String {
        self.writer.finish_string()
    }

    /// Finish and return output with trailing newline (for documents).
    fn finish_document(self) -> String {
        String::from_utf8(self.writer.finish_document())
            .expect("Styx output should always be valid UTF-8")
    }

    fn format_root(&mut self, value: &Value) {
        // Root is typically an untagged object
        if value.tag.is_none()
            && let Some(Payload::Object(obj)) = &value.payload
        {
            // Root object - no braces
            self.writer.begin_struct(true);
            self.format_object_entries(obj);
            self.writer.end_struct().ok();
            return;
        }
        // Non-object root or tagged root - just format the value
        self.format_value(value);
    }

    fn format_value(&mut self, value: &Value) {
        let has_tag = value.tag.is_some();

        // Write tag if present
        if let Some(tag) = &value.tag {
            self.writer.write_tag(&tag.name);
        }

        // Write payload if present
        match &value.payload {
            None => {
                // No payload - if no tag either, this is unit (@)
                if !has_tag {
                    self.writer.write_str("@");
                }
                // If there's a tag but no payload, tag was already written
            }
            Some(Payload::Scalar(s)) => {
                // If tagged, wrap scalar in parens: @tag(scalar)
                if has_tag {
                    self.writer.begin_seq_after_tag();
                    self.writer.write_scalar(&s.text);
                    self.writer.end_seq().ok();
                } else {
                    self.writer.write_scalar(&s.text);
                }
            }
            Some(Payload::Sequence(seq)) => {
                // If tagged, sequence attaches directly: @tag(...)
                self.format_sequence_inner(seq, has_tag);
            }
            Some(Payload::Object(obj)) => {
                // If tagged, object attaches directly: @tag{...}
                self.format_object_inner(obj, has_tag);
            }
        }
    }

    fn format_sequence_inner(&mut self, seq: &Sequence, after_tag: bool) {
        if after_tag {
            self.writer.begin_seq_after_tag();
        } else {
            self.writer.begin_seq();
        }
        for item in &seq.items {
            self.format_value(item);
        }
        self.writer.end_seq().ok();
    }

    fn format_object(&mut self, obj: &Object) {
        self.format_object_inner(obj, false);
    }

    fn format_object_inner(&mut self, obj: &Object, after_tag: bool) {
        // Use heuristics: multiline if more than 2 entries or any entry has nested structure
        let force_multiline = obj.entries.len() > 2
            || obj.entries.iter().any(|e| {
                e.value
                    .payload
                    .as_ref()
                    .map(|p| {
                        matches!(
                            p,
                            styx_tree::Payload::Object(_) | styx_tree::Payload::Sequence(_)
                        )
                    })
                    .unwrap_or(false)
            });
        if after_tag {
            self.writer.begin_struct_after_tag(force_multiline);
        } else {
            self.writer
                .begin_struct_with_options(false, force_multiline);
        }
        self.format_object_entries(obj);
        self.writer.end_struct().ok();
    }

    fn format_object_entries(&mut self, obj: &Object) {
        for entry in &obj.entries {
            self.format_entry(entry);
        }
    }

    fn format_entry(&mut self, entry: &Entry) {
        // Format the key (which is itself a Value - scalar or unit, optionally tagged)
        let key_str = self.format_key(&entry.key);

        // Write doc comment + key together, or just key
        if let Some(doc) = &entry.doc_comment {
            self.writer.write_doc_comment_and_key_raw(doc, &key_str);
        } else {
            self.writer.field_key_raw(&key_str).ok();
        }

        self.format_value(&entry.value);
    }

    /// Format a key value to string.
    /// Keys are scalars or unit, optionally tagged.
    fn format_key(&self, key: &Value) -> String {
        let mut result = String::new();

        // Tag prefix if present
        if let Some(tag) = &key.tag {
            result.push('@');
            result.push_str(&tag.name);
        }

        // Payload (scalar text or unit)
        match &key.payload {
            None => {
                // Unit - if no tag, write @
                if key.tag.is_none() {
                    result.push('@');
                }
                // If tagged with no payload, tag is already written (e.g., @schema)
            }
            Some(Payload::Scalar(s)) => {
                // Always check if the text can be bare, regardless of original ScalarKind
                if crate::scalar::can_be_bare(&s.text) {
                    result.push_str(&s.text);
                } else {
                    result.push('"');
                    result.push_str(&crate::scalar::escape_quoted(&s.text));
                    result.push('"');
                }
            }
            Some(Payload::Sequence(_) | Payload::Object(_)) => {
                panic!("object key cannot be a sequence or object: {:?}", key);
            }
        }

        result
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use styx_parse::ScalarKind;
    use styx_tree::{Object, Payload, Scalar, Sequence, Tag};

    fn scalar(text: &str) -> Value {
        Value {
            tag: None,
            payload: Some(Payload::Scalar(Scalar {
                text: text.to_string(),
                kind: ScalarKind::Bare,
                span: None,
            })),
            span: None,
        }
    }

    fn tagged(name: &str) -> Value {
        Value {
            tag: Some(Tag {
                name: name.to_string(),
                span: None,
            }),
            payload: None,
            span: None,
        }
    }

    fn entry(key: &str, value: Value) -> Entry {
        Entry {
            key: scalar(key),
            value,
            doc_comment: None,
        }
    }

    fn entry_with_doc(key: &str, value: Value, doc: &str) -> Entry {
        Entry {
            key: scalar(key),
            value,
            doc_comment: Some(doc.to_string()),
        }
    }

    fn obj_value(entries: Vec<Entry>) -> Value {
        Value {
            tag: None,
            payload: Some(Payload::Object(Object {
                entries,
                span: None,
            })),
            span: None,
        }
    }

    fn seq_value(items: Vec<Value>) -> Value {
        Value {
            tag: None,
            payload: Some(Payload::Sequence(Sequence { items, span: None })),
            span: None,
        }
    }

    #[test]
    fn test_format_simple_object() {
        let obj = obj_value(vec![
            entry("name", scalar("Alice")),
            entry("age", scalar("30")),
        ]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    #[test]
    fn test_format_nested_object() {
        let inner = Value {
            tag: None,
            payload: Some(Payload::Object(Object {
                entries: vec![entry("name", scalar("Alice")), entry("age", scalar("30"))],
                span: None,
            })),
            span: None,
        };

        let obj = obj_value(vec![entry("user", inner)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    #[test]
    fn test_format_tagged() {
        let obj = obj_value(vec![entry("type", tagged("string"))]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    #[test]
    fn test_format_sequence() {
        let seq = seq_value(vec![scalar("a"), scalar("b"), scalar("c")]);

        let obj = obj_value(vec![entry("items", seq)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    #[test]
    fn test_format_with_doc_comments() {
        let obj = obj_value(vec![
            entry_with_doc("name", scalar("Alice"), "The user's name"),
            entry_with_doc("age", scalar("30"), "Age in years"),
        ]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    #[test]
    fn test_format_unit() {
        let obj = obj_value(vec![entry("flag", Value::unit())]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // =========================================================================
    // Edge case tests for formatting
    // =========================================================================

    /// Helper to create an object value
    fn obj_multiline(entries: Vec<Entry>) -> Value {
        Value {
            tag: None,
            payload: Some(Payload::Object(Object {
                entries,
                span: None,
            })),
            span: None,
        }
    }

    /// Helper to create an inline object value (same as multiline now)
    fn obj_inline(entries: Vec<Entry>) -> Value {
        Value {
            tag: None,
            payload: Some(Payload::Object(Object {
                entries,
                span: None,
            })),
            span: None,
        }
    }

    /// Helper to create a tagged value with object payload
    fn tagged_obj(tag_name: &str, entries: Vec<Entry>) -> Value {
        Value {
            tag: Some(Tag {
                name: tag_name.to_string(),
                span: None,
            }),
            payload: Some(Payload::Object(Object {
                entries,
                span: None,
            })),
            span: None,
        }
    }

    /// Helper to create a tagged value with a single scalar payload
    fn tagged_scalar(tag_name: &str, text: &str) -> Value {
        Value {
            tag: Some(Tag {
                name: tag_name.to_string(),
                span: None,
            }),
            payload: Some(Payload::Scalar(Scalar {
                text: text.to_string(),
                kind: ScalarKind::Bare,
                span: None,
            })),
            span: None,
        }
    }

    /// Helper to create a unit entry (@ key)
    fn unit_entry(value: Value) -> Entry {
        Entry {
            key: Value::unit(),
            value,
            doc_comment: None,
        }
    }

    /// Helper to create a schema declaration entry (@schema key)
    fn schema_entry(value: Value) -> Entry {
        Entry {
            key: Value::tag("schema"),
            value,
            doc_comment: None,
        }
    }

    // --- Edge Case 1: Schema declaration with blank line after ---
    #[test]
    fn test_edge_case_01_schema_declaration_blank_line() {
        // @schema schema.styx followed by other fields should have blank line
        let obj = obj_multiline(vec![
            schema_entry(scalar("schema.styx")),
            entry("name", scalar("test")),
            entry("port", scalar("8080")),
        ]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 2: Nested multiline objects preserve structure ---
    #[test]
    fn test_edge_case_02_nested_multiline_objects() {
        let inner = obj_multiline(vec![
            entry("host", scalar("localhost")),
            entry("port", scalar("8080")),
        ]);
        let obj = obj_multiline(vec![entry("name", scalar("myapp")), entry("server", inner)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 3: Deeply nested multiline objects (3 levels) ---
    #[test]
    fn test_edge_case_03_deeply_nested_multiline() {
        let level3 = obj_multiline(vec![
            entry("cert", scalar("/path/to/cert")),
            entry("key", scalar("/path/to/key")),
        ]);
        let level2 = obj_multiline(vec![
            entry("host", scalar("localhost")),
            entry("tls", level3),
        ]);
        let obj = obj_multiline(vec![
            entry("name", scalar("myapp")),
            entry("server", level2),
        ]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 4: Mixed inline and multiline ---
    #[test]
    fn test_edge_case_04_mixed_inline_multiline() {
        // Outer is multiline, inner is inline
        let inner = obj_inline(vec![entry("x", scalar("1")), entry("y", scalar("2"))]);
        let obj = obj_multiline(vec![entry("name", scalar("point")), entry("coords", inner)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 5: Tagged object with multiline content ---
    #[test]
    fn test_edge_case_05_tagged_multiline_object() {
        let obj = obj_multiline(vec![entry(
            "type",
            tagged_obj(
                "object",
                vec![entry("name", tagged("string")), entry("age", tagged("int"))],
            ),
        )]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 6: Tagged object with inline content ---
    #[test]
    fn test_edge_case_06_tagged_inline_object() {
        let obj = obj_multiline(vec![entry(
            "point",
            tagged_obj(
                "point",
                vec![entry("x", scalar("1")), entry("y", scalar("2"))],
            ),
        )]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 7: Schema-like structure with @object tags ---
    #[test]
    fn test_edge_case_07_schema_structure() {
        // meta { ... }
        // schema { @ @object{ ... } }
        let meta = obj_multiline(vec![
            entry("id", scalar("https://example.com/schema")),
            entry("version", scalar("1.0")),
        ]);
        let schema_obj = tagged_obj(
            "object",
            vec![
                entry("name", tagged("string")),
                entry("port", tagged("int")),
            ],
        );
        let schema = obj_multiline(vec![unit_entry(schema_obj)]);
        let root = obj_multiline(vec![entry("meta", meta), entry("schema", schema)]);

        let result = format_value_default(&root);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 8: Optional wrapped types ---
    #[test]
    fn test_edge_case_08_optional_types() {
        let obj = obj_multiline(vec![
            entry("required", tagged("string")),
            entry("optional", tagged_scalar("optional", "@bool")),
        ]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 9: Empty object ---
    #[test]
    fn test_edge_case_09_empty_object() {
        let obj = obj_multiline(vec![entry("empty", obj_multiline(vec![]))]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 10: Empty inline object ---
    #[test]
    fn test_edge_case_10_empty_inline_object() {
        let obj = obj_multiline(vec![entry("empty", obj_inline(vec![]))]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 11: Sequence of objects ---
    #[test]
    fn test_edge_case_11_sequence_of_objects() {
        let item1 = obj_inline(vec![entry("name", scalar("Alice"))]);
        let item2 = obj_inline(vec![entry("name", scalar("Bob"))]);
        let seq = Value {
            tag: None,
            payload: Some(Payload::Sequence(Sequence {
                items: vec![item1, item2],
                span: None,
            })),
            span: None,
        };
        let obj = obj_multiline(vec![entry("users", seq)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 12: Quoted strings that need escaping ---
    #[test]
    fn test_edge_case_12_quoted_strings() {
        let obj = obj_multiline(vec![
            entry("message", scalar(r#""Hello, World!""#)),
            entry("path", scalar("/path/with spaces/file.txt")),
        ]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 13: Keys that need quoting ---
    #[test]
    fn test_edge_case_13_quoted_keys() {
        let obj = obj_multiline(vec![
            entry("normal-key", scalar("value1")),
            entry("key with spaces", scalar("value2")),
            entry("123numeric", scalar("value3")),
        ]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 14: Schema declaration (now using @schema tag) ---
    #[test]
    fn test_edge_case_14_schema_declaration() {
        let obj = obj_multiline(vec![
            schema_entry(scalar("first.styx")),
            entry("name", scalar("test")),
        ]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 15: Nested sequences ---
    #[test]
    fn test_edge_case_15_nested_sequences() {
        let inner_seq = seq_value(vec![scalar("a"), scalar("b")]);
        let outer_seq = Value {
            tag: None,
            payload: Some(Payload::Sequence(Sequence {
                items: vec![inner_seq, seq_value(vec![scalar("c"), scalar("d")])],
                span: None,
            })),
            span: None,
        };
        let obj = obj_multiline(vec![entry("matrix", outer_seq)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 16: Tagged sequence ---
    #[test]
    fn test_edge_case_16_tagged_sequence() {
        let tagged_seq = Value {
            tag: Some(Tag {
                name: "seq".to_string(),
                span: None,
            }),
            payload: Some(Payload::Sequence(Sequence {
                items: vec![tagged("string")],
                span: None,
            })),
            span: None,
        };
        let obj = obj_multiline(vec![entry("items", tagged_seq)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 17: Doc comments on nested entries ---
    #[test]
    fn test_edge_case_17_nested_doc_comments() {
        let inner = Value {
            tag: None,
            payload: Some(Payload::Object(Object {
                entries: vec![
                    entry_with_doc("host", scalar("localhost"), "The server hostname"),
                    entry_with_doc("port", scalar("8080"), "The server port"),
                ],
                span: None,
            })),
            span: None,
        };
        let obj = obj_multiline(vec![entry_with_doc(
            "server",
            inner,
            "Server configuration",
        )]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 18: Very long inline object should stay inline if marked ---
    #[test]
    fn test_edge_case_18_long_inline_stays_inline() {
        let inner = obj_inline(vec![
            entry("field1", scalar("value1")),
            entry("field2", scalar("value2")),
            entry("field3", scalar("value3")),
            entry("field4", scalar("value4")),
        ]);
        let obj = obj_multiline(vec![entry("data", inner)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 19: Multiline with single field ---
    #[test]
    fn test_edge_case_19_multiline_single_field() {
        let inner = obj_multiline(vec![entry("only", scalar("one"))]);
        let obj = obj_multiline(vec![entry("wrapper", inner)]);

        let result = format_value_default(&obj);
        insta::assert_snapshot!(result);
    }

    // --- Edge Case 20: Full schema file simulation ---
    #[test]
    fn test_edge_case_20_full_schema_simulation() {
        // Simulates: meta { id ..., version ..., description ... }
        //            schema { @ @object{ name @string, server @object{ host @string, port @int } } }
        let meta = obj_multiline(vec![
            entry("id", scalar("https://example.com/config")),
            entry("version", scalar("2024-01-01")),
            entry("description", scalar("\"A test schema\"")),
        ]);

        let _server_fields = obj_multiline(vec![
            entry("host", tagged("string")),
            entry("port", tagged("int")),
        ]);
        let server_schema = tagged_obj(
            "object",
            vec![
                entry("host", tagged("string")),
                entry("port", tagged("int")),
            ],
        );

        let root_schema = tagged_obj(
            "object",
            vec![
                entry("name", tagged("string")),
                entry("server", server_schema),
            ],
        );

        let schema = obj_multiline(vec![unit_entry(root_schema)]);

        let root = obj_multiline(vec![entry("meta", meta), entry("schema", schema)]);

        let result = format_value_default(&root);
        insta::assert_snapshot!(result);
    }

    // =========================================================================
    // Blank line behavior tests - testing against CST formatter as source of truth
    // =========================================================================

    /// Test that ValueFormatter output matches CST formatter for the same input.
    /// This is the key idempotency property we need.
    fn assert_matches_cst_formatter(value: &Value, description: &str) {
        let value_output = format_value_default(value);
        let cst_output = crate::format_source(&value_output, crate::FormatOptions::default());
        assert_eq!(
            value_output, cst_output,
            "{}: ValueFormatter output should match CST formatter.\n\
             ValueFormatter produced:\n{}\n\
             CST formatter would produce:\n{}",
            description, value_output, cst_output
        );
    }

    #[test]
    fn blank_line_01_two_scalars_at_root() {
        // Two scalar entries at root - no blank line needed
        let obj = obj_multiline(vec![
            entry("name", scalar("Alice")),
            entry("age", scalar("30")),
        ]);
        assert_matches_cst_formatter(&obj, "two scalars at root");
    }

    #[test]
    fn blank_line_02_three_scalars_at_root() {
        let obj = obj_multiline(vec![
            entry("a", scalar("1")),
            entry("b", scalar("2")),
            entry("c", scalar("3")),
        ]);
        assert_matches_cst_formatter(&obj, "three scalars at root");
    }

    #[test]
    fn blank_line_03_scalar_then_block() {
        // Scalar followed by block object - needs blank line before block
        let block = obj_multiline(vec![
            entry("host", scalar("localhost")),
            entry("port", scalar("8080")),
        ]);
        let obj = obj_multiline(vec![entry("name", scalar("myapp")), entry("server", block)]);
        assert_matches_cst_formatter(&obj, "scalar then block");
    }

    #[test]
    fn blank_line_04_block_then_scalar() {
        // Block followed by scalar - needs blank line after block
        let block = obj_multiline(vec![entry("host", scalar("localhost"))]);
        let obj = obj_multiline(vec![entry("server", block), entry("name", scalar("myapp"))]);
        assert_matches_cst_formatter(&obj, "block then scalar");
    }

    #[test]
    fn blank_line_05_two_blocks() {
        // Two block objects - needs blank line between them
        let block1 = obj_multiline(vec![entry("a", scalar("1"))]);
        let block2 = obj_multiline(vec![entry("b", scalar("2"))]);
        let obj = obj_multiline(vec![entry("first", block1), entry("second", block2)]);
        assert_matches_cst_formatter(&obj, "two blocks");
    }

    #[test]
    fn blank_line_06_inline_objects_at_root() {
        // Inline objects at root - no blank line needed
        let inline1 = obj_inline(vec![entry("x", scalar("1"))]);
        let inline2 = obj_inline(vec![entry("y", scalar("2"))]);
        let obj = obj_multiline(vec![entry("point1", inline1), entry("point2", inline2)]);
        assert_matches_cst_formatter(&obj, "inline objects at root");
    }

    #[test]
    fn blank_line_07_scalar_inline_scalar() {
        let inline = obj_inline(vec![entry("x", scalar("1"))]);
        let obj = obj_multiline(vec![
            entry("name", scalar("test")),
            entry("point", inline),
            entry("count", scalar("5")),
        ]);
        assert_matches_cst_formatter(&obj, "scalar inline scalar");
    }

    #[test]
    fn blank_line_08_doc_comment_entries() {
        // Entries with doc comments
        let obj = obj_multiline(vec![
            entry_with_doc("name", scalar("Alice"), "The user's name"),
            entry_with_doc("age", scalar("30"), "Age in years"),
        ]);
        assert_matches_cst_formatter(&obj, "doc comment entries");
    }

    #[test]
    fn blank_line_09_mixed_doc_and_plain() {
        let obj = obj_multiline(vec![
            entry("plain", scalar("1")),
            entry_with_doc("documented", scalar("2"), "Has docs"),
            entry("another_plain", scalar("3")),
        ]);
        assert_matches_cst_formatter(&obj, "mixed doc and plain");
    }

    #[test]
    fn blank_line_10_schema_declaration_first() {
        // Schema declaration at start should have blank line after
        let obj = obj_multiline(vec![
            schema_entry(scalar("schema.styx")),
            entry("name", scalar("test")),
        ]);
        assert_matches_cst_formatter(&obj, "schema declaration first");
    }

    #[test]
    fn blank_line_11_nested_blocks_dont_get_extra_blanks() {
        // Inside a non-root object, no extra blank lines
        let inner = obj_multiline(vec![entry("a", scalar("1")), entry("b", scalar("2"))]);
        let obj = obj_multiline(vec![entry("wrapper", inner)]);
        assert_matches_cst_formatter(&obj, "nested block internal");
    }

    #[test]
    fn blank_line_12_deeply_nested() {
        let level3 = obj_multiline(vec![entry("deep", scalar("value"))]);
        let level2 = obj_multiline(vec![entry("inner", level3)]);
        let obj = obj_multiline(vec![
            entry("outer", level2),
            entry("sibling", scalar("test")),
        ]);
        assert_matches_cst_formatter(&obj, "deeply nested");
    }

    #[test]
    fn blank_line_13_tagged_block() {
        let tagged_block = tagged_obj("object", vec![entry("field", tagged("string"))]);
        let obj = obj_multiline(vec![
            entry("name", scalar("test")),
            entry("schema", tagged_block),
        ]);
        assert_matches_cst_formatter(&obj, "tagged block");
    }

    #[test]
    fn blank_line_14_sequence_of_scalars() {
        let seq = seq_value(vec![scalar("a"), scalar("b"), scalar("c")]);
        let obj = obj_multiline(vec![entry("items", seq), entry("count", scalar("3"))]);
        assert_matches_cst_formatter(&obj, "sequence of scalars");
    }

    #[test]
    fn blank_line_15_meta_then_schema_block() {
        // Real-world pattern: meta block followed by schema block
        let meta = obj_multiline(vec![
            entry("id", scalar("test")),
            entry("version", scalar("1")),
        ]);
        let schema_content = tagged_obj("object", vec![entry("name", tagged("string"))]);
        let schema = obj_multiline(vec![unit_entry(schema_content)]);
        let obj = obj_multiline(vec![entry("meta", meta), entry("schema", schema)]);
        assert_matches_cst_formatter(&obj, "meta then schema block");
    }

    #[test]
    fn blank_line_16_three_blocks() {
        let b1 = obj_multiline(vec![entry("a", scalar("1"))]);
        let b2 = obj_multiline(vec![entry("b", scalar("2"))]);
        let b3 = obj_multiline(vec![entry("c", scalar("3"))]);
        let obj = obj_multiline(vec![
            entry("first", b1),
            entry("second", b2),
            entry("third", b3),
        ]);
        assert_matches_cst_formatter(&obj, "three blocks");
    }

    #[test]
    fn blank_line_17_block_with_doc_comment() {
        let block = obj_multiline(vec![entry("inner", scalar("value"))]);
        let obj = obj_multiline(vec![
            entry_with_doc("config", block, "Configuration section"),
            entry("name", scalar("test")),
        ]);
        assert_matches_cst_formatter(&obj, "block with doc comment");
    }

    #[test]
    fn blank_line_18_empty_inline_objects() {
        let empty1 = obj_inline(vec![]);
        let empty2 = obj_inline(vec![]);
        let obj = obj_multiline(vec![entry("a", empty1), entry("b", empty2)]);
        assert_matches_cst_formatter(&obj, "empty inline objects");
    }

    #[test]
    fn blank_line_19_single_entry_block() {
        let block = obj_multiline(vec![entry("only", scalar("one"))]);
        let obj = obj_multiline(vec![entry("wrapper", block)]);
        assert_matches_cst_formatter(&obj, "single entry block");
    }

    #[test]
    fn blank_line_20_alternating_scalar_block() {
        let b1 = obj_multiline(vec![entry("x", scalar("1"))]);
        let b2 = obj_multiline(vec![entry("y", scalar("2"))]);
        let obj = obj_multiline(vec![
            entry("s1", scalar("a")),
            entry("block1", b1),
            entry("s2", scalar("b")),
            entry("block2", b2),
            entry("s3", scalar("c")),
        ]);
        assert_matches_cst_formatter(&obj, "alternating scalar block");
    }
}