diff --git a/cli/src/generate/mod.rs b/cli/src/generate/mod.rs
index 9e640423..b5c4c0e4 100644
--- a/cli/src/generate/mod.rs
+++ b/cli/src/generate/mod.rs
@@ -1,15 +1,10 @@
 use self::build_tables::build_tables;
-use self::grammars::{LexicalGrammar, SyntaxGrammar, VariableType};
 use self::parse_grammar::parse_grammar;
 use self::prepare_grammar::prepare_grammar;
 use self::render::render_c_code;
-use self::rules::{AliasMap, Symbol, SymbolType};
-use self::tables::{ChildType, VariableInfo};
 use crate::error::{Error, Result};
 use lazy_static::lazy_static;
 use regex::{Regex, RegexBuilder};
-use serde_derive::Serialize;
-use std::collections::BTreeMap;
 use std::fs;
 use std::io::Write;
 use std::path::{Path, PathBuf};
@@ -18,6 +13,7 @@ use std::process::{Command, Stdio};
 mod build_tables;
 mod grammars;
 mod nfa;
+mod node_types;
 mod npm_files;
 mod parse_grammar;
 mod prepare_grammar;
@@ -112,7 +108,7 @@ fn generate_parser_for_grammar_with_opts(
         state_ids_to_log,
     )?;
     let name = input_grammar.name;
-    let node_types_json = generate_node_types_json(
+    let node_types_json = node_types::generate_node_types_json(
         &syntax_grammar,
         &lexical_grammar,
         &simple_aliases,
@@ -131,7 +127,7 @@ fn generate_parser_for_grammar_with_opts(
     Ok(GeneratedParser {
         name,
         c_code,
-        node_types_json,
+        node_types_json: serde_json::to_string_pretty(&node_types_json).unwrap(),
     })
 }
 
@@ -185,133 +181,3 @@ fn ensure_file<T: AsRef<[u8]>>(path: &PathBuf, f: impl Fn() -> T) -> Result<()>
             .map_err(|e| Error(format!("Failed to write file {:?}: {}", path, e)))
     }
 }
-
-#[derive(Debug, Serialize, PartialEq, Eq, Default)]
-struct NodeInfoJSON {
-    #[serde(rename = "type")]
-    name: String,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    fields: Option<BTreeMap<String, FieldInfoJSON>>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    subtypes: Option<Vec<NodeTypeJSON>>,
-}
-
-#[derive(Debug, Serialize, PartialEq, Eq, PartialOrd, Ord)]
-struct NodeTypeJSON {
-    #[serde(rename = "type")]
-    kind: String,
-    named: bool,
-}
-
-#[derive(Debug, Serialize, PartialEq, Eq)]
-struct FieldInfoJSON {
-    multiple: bool,
-    required: bool,
-    types: Vec<NodeTypeJSON>,
-}
-
-fn generate_node_types_json(
-    syntax_grammar: &SyntaxGrammar,
-    lexical_grammar: &LexicalGrammar,
-    simple_aliases: &AliasMap,
-    variable_info: &Vec<VariableInfo>,
-) -> String {
-    let mut node_types_json = BTreeMap::new();
-
-    let child_type_to_node_type = |child_type: &ChildType| match child_type {
-        ChildType::Aliased(alias) => NodeTypeJSON {
-            kind: alias.value.clone(),
-            named: alias.is_named,
-        },
-        ChildType::Normal(symbol) => {
-            if let Some(alias) = simple_aliases.get(&symbol) {
-                NodeTypeJSON {
-                    kind: alias.value.clone(),
-                    named: alias.is_named,
-                }
-            } else {
-                match symbol.kind {
-                    SymbolType::NonTerminal => {
-                        let variable = &syntax_grammar.variables[symbol.index];
-                        NodeTypeJSON {
-                            kind: variable.name.clone(),
-                            named: variable.kind == VariableType::Named,
-                        }
-                    }
-                    SymbolType::Terminal => {
-                        let variable = &lexical_grammar.variables[symbol.index];
-                        NodeTypeJSON {
-                            kind: variable.name.clone(),
-                            named: variable.kind == VariableType::Named,
-                        }
-                    }
-                    SymbolType::External => {
-                        let variable = &syntax_grammar.external_tokens[symbol.index];
-                        NodeTypeJSON {
-                            kind: variable.name.clone(),
-                            named: variable.kind == VariableType::Named,
-                        }
-                    }
-                    _ => panic!("Unexpected symbol type"),
-                }
-            }
-        }
-    };
-
-    for (i, info) in variable_info.iter().enumerate() {
-        let symbol = Symbol::non_terminal(i);
-        let variable = &syntax_grammar.variables[i];
-        let name = simple_aliases
-            .get(&Symbol::non_terminal(i))
-            .map_or(&variable.name, |alias| &alias.value);
-
-        if syntax_grammar.supertype_symbols.contains(&symbol) {
-            let node_type_json =
-                node_types_json
-                    .entry(name.clone())
-                    .or_insert_with(|| NodeInfoJSON {
-                        name: name.clone(),
-                        fields: None,
-                        subtypes: None,
-                    });
-            let mut subtypes = info.child_types
-                .iter()
-                .map(child_type_to_node_type)
-                .collect::<Vec<_>>();
-            subtypes.sort_unstable();
-            subtypes.dedup();
-            node_type_json.subtypes = Some(subtypes);
-
-        } else if variable.kind.is_visible() {
-            let node_type_json =
-                node_types_json
-                    .entry(name.clone())
-                    .or_insert_with(|| NodeInfoJSON {
-                        name: name.clone(),
-                        fields: None,
-                        subtypes: None,
-                    });
-            let mut fields_json = BTreeMap::new();
-            for (field, field_info) in info.fields.iter() {
-                let field_info_json = fields_json.entry(field.clone()).or_insert(FieldInfoJSON {
-                    multiple: false,
-                    required: true,
-                    types: Vec::new(),
-                });
-
-                field_info_json.multiple |= field_info.multiple;
-                field_info_json.required &= field_info.required;
-                field_info_json
-                    .types
-                    .extend(field_info.types.iter().map(child_type_to_node_type));
-                field_info_json.types.sort_unstable();
-                field_info_json.types.dedup();
-            }
-            node_type_json.fields = Some(fields_json);
-        }
-    }
-
-    let node_types_json = node_types_json.values().collect::<Vec<_>>();
-
-    serde_json::to_string_pretty(&node_types_json).unwrap()
-}
diff --git a/cli/src/generate/node_types.rs b/cli/src/generate/node_types.rs
new file mode 100644
index 00000000..35129189
--- /dev/null
+++ b/cli/src/generate/node_types.rs
@@ -0,0 +1,133 @@
+use super::grammars::{LexicalGrammar, SyntaxGrammar, VariableType};
+use super::rules::{AliasMap, Symbol, SymbolType};
+use super::tables::{ChildType, VariableInfo};
+use serde_derive::Serialize;
+use std::collections::BTreeMap;
+
+#[derive(Debug, Serialize, PartialEq, Eq, Default)]
+pub(crate) struct NodeInfoJSON {
+    #[serde(rename = "type")]
+    name: String,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    fields: Option<BTreeMap<String, FieldInfoJSON>>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    subtypes: Option<Vec<NodeTypeJSON>>,
+}
+
+#[derive(Debug, Serialize, PartialEq, Eq, PartialOrd, Ord)]
+pub(crate) struct NodeTypeJSON {
+    #[serde(rename = "type")]
+    kind: String,
+    named: bool,
+}
+
+#[derive(Debug, Serialize, PartialEq, Eq)]
+pub(crate) struct FieldInfoJSON {
+    multiple: bool,
+    required: bool,
+    types: Vec<NodeTypeJSON>,
+}
+
+pub(crate) fn generate_node_types_json(
+    syntax_grammar: &SyntaxGrammar,
+    lexical_grammar: &LexicalGrammar,
+    simple_aliases: &AliasMap,
+    variable_info: &Vec<VariableInfo>,
+) -> Vec<NodeInfoJSON> {
+    let mut node_types_json = BTreeMap::new();
+
+    let child_type_to_node_type = |child_type: &ChildType| match child_type {
+        ChildType::Aliased(alias) => NodeTypeJSON {
+            kind: alias.value.clone(),
+            named: alias.is_named,
+        },
+        ChildType::Normal(symbol) => {
+            if let Some(alias) = simple_aliases.get(&symbol) {
+                NodeTypeJSON {
+                    kind: alias.value.clone(),
+                    named: alias.is_named,
+                }
+            } else {
+                match symbol.kind {
+                    SymbolType::NonTerminal => {
+                        let variable = &syntax_grammar.variables[symbol.index];
+                        NodeTypeJSON {
+                            kind: variable.name.clone(),
+                            named: variable.kind == VariableType::Named,
+                        }
+                    }
+                    SymbolType::Terminal => {
+                        let variable = &lexical_grammar.variables[symbol.index];
+                        NodeTypeJSON {
+                            kind: variable.name.clone(),
+                            named: variable.kind == VariableType::Named,
+                        }
+                    }
+                    SymbolType::External => {
+                        let variable = &syntax_grammar.external_tokens[symbol.index];
+                        NodeTypeJSON {
+                            kind: variable.name.clone(),
+                            named: variable.kind == VariableType::Named,
+                        }
+                    }
+                    _ => panic!("Unexpected symbol type"),
+                }
+            }
+        }
+    };
+
+    for (i, info) in variable_info.iter().enumerate() {
+        let symbol = Symbol::non_terminal(i);
+        let variable = &syntax_grammar.variables[i];
+        let name = simple_aliases
+            .get(&Symbol::non_terminal(i))
+            .map_or(&variable.name, |alias| &alias.value);
+
+        if syntax_grammar.supertype_symbols.contains(&symbol) {
+            let node_type_json =
+                node_types_json
+                    .entry(name.clone())
+                    .or_insert_with(|| NodeInfoJSON {
+                        name: name.clone(),
+                        fields: None,
+                        subtypes: None,
+                    });
+            let mut subtypes = info
+                .child_types
+                .iter()
+                .map(child_type_to_node_type)
+                .collect::<Vec<_>>();
+            subtypes.sort_unstable();
+            subtypes.dedup();
+            node_type_json.subtypes = Some(subtypes);
+        } else if variable.kind.is_visible() {
+            let node_type_json =
+                node_types_json
+                    .entry(name.clone())
+                    .or_insert_with(|| NodeInfoJSON {
+                        name: name.clone(),
+                        fields: None,
+                        subtypes: None,
+                    });
+            let mut fields_json = BTreeMap::new();
+            for (field, field_info) in info.fields.iter() {
+                let field_info_json = fields_json.entry(field.clone()).or_insert(FieldInfoJSON {
+                    multiple: false,
+                    required: true,
+                    types: Vec::new(),
+                });
+
+                field_info_json.multiple |= field_info.multiple;
+                field_info_json.required &= field_info.required;
+                field_info_json
+                    .types
+                    .extend(field_info.types.iter().map(child_type_to_node_type));
+                field_info_json.types.sort_unstable();
+                field_info_json.types.dedup();
+            }
+            node_type_json.fields = Some(fields_json);
+        }
+    }
+
+    node_types_json.into_iter().map(|e| e.1).collect()
+}