diff --git a/cli/checksum.rs b/cli/checksum.rs
index 41e15db2fb4a8d..a86f527c031bf4 100644
--- a/cli/checksum.rs
+++ b/cli/checksum.rs
@@ -1,9 +1,12 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 
-pub fn gen(v: &[&[u8]]) -> String {
-  let mut ctx = ring::digest::Context::new(&ring::digest::SHA256);
+use ring::digest::Context;
+use ring::digest::SHA256;
+
+pub fn gen(v: &[impl AsRef<[u8]>]) -> String {
+  let mut ctx = Context::new(&SHA256);
   for src in v {
-    ctx.update(src);
+    ctx.update(src.as_ref());
   }
   let digest = ctx.finish();
   let out: Vec<String> = digest
@@ -13,3 +16,17 @@ pub fn gen(v: &[&[u8]]) -> String {
     .collect();
   out.join("")
 }
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn test_gen() {
+    let actual = gen(&[b"hello world"]);
+    assert_eq!(
+      actual,
+      "b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9"
+    );
+  }
+}
diff --git a/cli/diagnostics.rs b/cli/diagnostics.rs
index b3b5a73c3c7a7a..290007cc720974 100644
--- a/cli/diagnostics.rs
+++ b/cli/diagnostics.rs
@@ -127,7 +127,7 @@ fn format_message(msg: &str, code: &u64) -> String {
   }
 }
 
-#[derive(Clone, Debug, PartialEq)]
+#[derive(Clone, Debug, Eq, PartialEq)]
 pub enum DiagnosticCategory {
   Warning,
   Error,
@@ -172,7 +172,7 @@ impl From<i64> for DiagnosticCategory {
   }
 }
 
-#[derive(Debug, Deserialize, Clone)]
+#[derive(Debug, Deserialize, Clone, Eq, PartialEq)]
 #[serde(rename_all = "camelCase")]
 pub struct DiagnosticMessageChain {
   message_text: String,
@@ -199,26 +199,26 @@ impl DiagnosticMessageChain {
   }
 }
 
-#[derive(Debug, Deserialize, Clone)]
+#[derive(Debug, Deserialize, Clone, Eq, PartialEq)]
 #[serde(rename_all = "camelCase")]
 pub struct Position {
   pub line: u64,
   pub character: u64,
 }
 
-#[derive(Debug, Deserialize, Clone)]
+#[derive(Debug, Deserialize, Clone, Eq, PartialEq)]
 #[serde(rename_all = "camelCase")]
 pub struct Diagnostic {
-  category: DiagnosticCategory,
-  code: u64,
-  start: Option<Position>,
-  end: Option<Position>,
-  message_text: Option<String>,
-  message_chain: Option<DiagnosticMessageChain>,
-  source: Option<String>,
-  source_line: Option<String>,
-  file_name: Option<String>,
-  related_information: Option<Vec<Diagnostic>>,
+  pub category: DiagnosticCategory,
+  pub code: u64,
+  pub start: Option<Position>,
+  pub end: Option<Position>,
+  pub message_text: Option<String>,
+  pub message_chain: Option<DiagnosticMessageChain>,
+  pub source: Option<String>,
+  pub source_line: Option<String>,
+  pub file_name: Option<String>,
+  pub related_information: Option<Vec<Diagnostic>>,
 }
 
 impl Diagnostic {
@@ -346,7 +346,7 @@ impl fmt::Display for Diagnostic {
   }
 }
 
-#[derive(Clone, Debug)]
+#[derive(Clone, Debug, Eq, PartialEq)]
 pub struct Diagnostics(pub Vec<Diagnostic>);
 
 impl<'de> Deserialize<'de> for Diagnostics {
diff --git a/cli/js.rs b/cli/js.rs
index d51d7dd92be25c..3d2a17f36d7842 100644
--- a/cli/js.rs
+++ b/cli/js.rs
@@ -57,7 +57,7 @@ fn compiler_snapshot() {
     .execute(
       "<anon>",
       r#"
-    if (!(bootstrapCompilerRuntime)) {
+    if (!(startup)) {
         throw Error("bad");
       }
       console.log(`ts version: ${ts.version}`);
diff --git a/cli/main.rs b/cli/main.rs
index f6bef9688ef54c..2947dfde2fa96a 100644
--- a/cli/main.rs
+++ b/cli/main.rs
@@ -51,6 +51,7 @@ mod test_runner;
 mod text_encoding;
 mod tokio_util;
 mod tsc;
+pub mod tsc2;
 mod tsc_config;
 mod upgrade;
 mod version;
diff --git a/cli/media_type.rs b/cli/media_type.rs
index cc3700a66b2917..5d083466be63c2 100644
--- a/cli/media_type.rs
+++ b/cli/media_type.rs
@@ -10,7 +10,7 @@ use std::path::PathBuf;
 // Update carefully!
 #[allow(non_camel_case_types)]
 #[repr(i32)]
-#[derive(Clone, Copy, PartialEq, Debug)]
+#[derive(Clone, Copy, Eq, PartialEq, Debug)]
 pub enum MediaType {
   JavaScript = 0,
   JSX = 1,
@@ -19,7 +19,9 @@ pub enum MediaType {
   TSX = 4,
   Json = 5,
   Wasm = 6,
-  Unknown = 8,
+  TsBuildInfo = 7,
+  SourceMap = 8,
+  Unknown = 9,
 }
 
 impl fmt::Display for MediaType {
@@ -32,6 +34,8 @@ impl fmt::Display for MediaType {
       MediaType::TSX => "TSX",
       MediaType::Json => "Json",
       MediaType::Wasm => "Wasm",
+      MediaType::TsBuildInfo => "TsBuildInfo",
+      MediaType::SourceMap => "SourceMap",
       MediaType::Unknown => "Unknown",
     };
     write!(f, "{}", value)
@@ -56,6 +60,12 @@ impl<'a> From<&'a String> for MediaType {
   }
 }
 
+impl Default for MediaType {
+  fn default() -> Self {
+    MediaType::Unknown
+  }
+}
+
 impl MediaType {
   fn from_path(path: &Path) -> Self {
     match path.extension() {
@@ -69,10 +79,42 @@ impl MediaType {
         Some("cjs") => MediaType::JavaScript,
         Some("json") => MediaType::Json,
         Some("wasm") => MediaType::Wasm,
+        Some("tsbuildinfo") => MediaType::TsBuildInfo,
+        Some("map") => MediaType::SourceMap,
         _ => MediaType::Unknown,
       },
     }
   }
+
+  /// Convert a MediaType to a `ts.Extension`.
+  ///
+  /// *NOTE* This is defined in TypeScript as a string based enum.  Changes to
+  /// that enum in TypeScript should be reflected here.
+  pub fn as_ts_extension(&self) -> String {
+    let ext = match self {
+      MediaType::JavaScript => ".js",
+      MediaType::JSX => ".jsx",
+      MediaType::TypeScript => ".ts",
+      MediaType::Dts => ".d.ts",
+      MediaType::TSX => ".tsx",
+      MediaType::Json => ".json",
+      // TypeScript doesn't have an "unknown", so we will treat WASM as JS for
+      // mapping purposes, though in reality, it is unlikely to ever be passed
+      // to the compiler.
+      MediaType::Wasm => ".js",
+      MediaType::TsBuildInfo => ".tsbuildinfo",
+      // TypeScript doesn't have an "source map", so we will treat SourceMap as
+      // JS for mapping purposes, though in reality, it is unlikely to ever be
+      // passed to the compiler.
+      MediaType::SourceMap => ".js",
+      // TypeScript doesn't have an "unknown", so we will treat WASM as JS for
+      // mapping purposes, though in reality, it is unlikely to ever be passed
+      // to the compiler.
+      MediaType::Unknown => ".js",
+    };
+
+    ext.into()
+  }
 }
 
 impl Serialize for MediaType {
@@ -88,7 +130,9 @@ impl Serialize for MediaType {
       MediaType::TSX => 4 as i32,
       MediaType::Json => 5 as i32,
       MediaType::Wasm => 6 as i32,
-      MediaType::Unknown => 8 as i32,
+      MediaType::TsBuildInfo => 7 as i32,
+      MediaType::SourceMap => 8 as i32,
+      MediaType::Unknown => 9 as i32,
     };
     Serialize::serialize(&value, serializer)
   }
@@ -132,6 +176,14 @@ mod tests {
       MediaType::from(Path::new("foo/bar.cjs")),
       MediaType::JavaScript
     );
+    assert_eq!(
+      MediaType::from(Path::new("foo/.tsbuildinfo")),
+      MediaType::TsBuildInfo
+    );
+    assert_eq!(
+      MediaType::from(Path::new("foo/bar.js.map")),
+      MediaType::SourceMap
+    );
     assert_eq!(
       MediaType::from(Path::new("foo/bar.txt")),
       MediaType::Unknown
@@ -148,7 +200,9 @@ mod tests {
     assert_eq!(json!(MediaType::TSX), json!(4));
     assert_eq!(json!(MediaType::Json), json!(5));
     assert_eq!(json!(MediaType::Wasm), json!(6));
-    assert_eq!(json!(MediaType::Unknown), json!(8));
+    assert_eq!(json!(MediaType::TsBuildInfo), json!(7));
+    assert_eq!(json!(MediaType::SourceMap), json!(8));
+    assert_eq!(json!(MediaType::Unknown), json!(9));
   }
 
   #[test]
@@ -160,6 +214,8 @@ mod tests {
     assert_eq!(format!("{}", MediaType::TSX), "TSX");
     assert_eq!(format!("{}", MediaType::Json), "Json");
     assert_eq!(format!("{}", MediaType::Wasm), "Wasm");
+    assert_eq!(format!("{}", MediaType::TsBuildInfo), "BuildInfo");
+    assert_eq!(format!("{}", MediaType::SourceMap), "SourceMap");
     assert_eq!(format!("{}", MediaType::Unknown), "Unknown");
   }
 }
diff --git a/cli/module_graph.rs b/cli/module_graph.rs
index a0ecb6d407fcfc..49521c7cce731e 100644
--- a/cli/module_graph.rs
+++ b/cli/module_graph.rs
@@ -465,7 +465,7 @@ impl ModuleGraphLoader {
           filename: source_file.filename.to_str().unwrap().to_string(),
           version_hash: checksum::gen(&[
             &source_file.source_code.as_bytes(),
-            version::DENO.as_bytes(),
+            &version::DENO.as_bytes(),
           ]),
           media_type: source_file.media_type,
           source_code: "".to_string(),
@@ -481,7 +481,7 @@ impl ModuleGraphLoader {
     let module_specifier = ModuleSpecifier::from(source_file.url.clone());
     let version_hash = checksum::gen(&[
       &source_file.source_code.as_bytes(),
-      version::DENO.as_bytes(),
+      &version::DENO.as_bytes(),
     ]);
     let source_code = source_file.source_code.clone();
 
diff --git a/cli/module_graph2.rs b/cli/module_graph2.rs
index 69858641342c84..ddda524c9f1310 100644
--- a/cli/module_graph2.rs
+++ b/cli/module_graph2.rs
@@ -41,7 +41,7 @@ use std::sync::Mutex;
 use std::time::Instant;
 use swc_ecmascript::dep_graph::DependencyKind;
 
-pub type BuildInfoMap = HashMap<EmitType, String>;
+pub type TsBuildInfoMap = HashMap<EmitType, String>;
 
 lazy_static! {
   /// Matched the `@deno-types` pragma.
@@ -379,8 +379,8 @@ impl Module {
   }
 }
 
-#[derive(Clone, Debug, PartialEq)]
-pub struct Stats(Vec<(String, u128)>);
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct Stats(pub Vec<(String, u128)>);
 
 impl<'de> Deserialize<'de> for Stats {
   fn deserialize<D>(deserializer: D) -> result::Result<Self, D::Error>
@@ -418,10 +418,10 @@ pub struct TranspileOptions {
 /// be able to manipulate and handle the graph.
 #[derive(Debug)]
 pub struct Graph2 {
-  build_info: BuildInfoMap,
   handler: Rc<RefCell<dyn SpecifierHandler>>,
   modules: HashMap<ModuleSpecifier, Module>,
   roots: Vec<ModuleSpecifier>,
+  ts_build_info: TsBuildInfoMap,
 }
 
 impl Graph2 {
@@ -432,10 +432,10 @@ impl Graph2 {
   ///
   pub fn new(handler: Rc<RefCell<dyn SpecifierHandler>>) -> Self {
     Graph2 {
-      build_info: HashMap::new(),
       handler,
       modules: HashMap::new(),
       roots: Vec::new(),
+      ts_build_info: HashMap::new(),
     }
   }
 
@@ -568,11 +568,11 @@ impl Graph2 {
       }
     }
     for root_specifier in self.roots.iter() {
-      if let Some(build_info) = self.build_info.get(&emit_type) {
-        handler.set_build_info(
+      if let Some(ts_build_info) = self.ts_build_info.get(&emit_type) {
+        handler.set_ts_build_info(
           root_specifier,
           &emit_type,
-          build_info.to_owned(),
+          ts_build_info.to_owned(),
         )?;
       }
     }
@@ -580,6 +580,27 @@ impl Graph2 {
     Ok(())
   }
 
+  pub fn get_media_type(
+    &self,
+    specifier: &ModuleSpecifier,
+  ) -> Option<MediaType> {
+    if let Some(module) = self.modules.get(specifier) {
+      Some(module.media_type)
+    } else {
+      None
+    }
+  }
+
+  /// Get the source for a given module specifier.  If the module is not part
+  /// of the graph, the result will be `None`.
+  pub fn get_source(&self, specifier: &ModuleSpecifier) -> Option<String> {
+    if let Some(module) = self.modules.get(specifier) {
+      Some(module.source.clone())
+    } else {
+      None
+    }
+  }
+
   /// Verify the subresource integrity of the graph based upon the optional
   /// lockfile, updating the lockfile with any missing resources.  This will
   /// error if any of the resources do not match their lock status.
@@ -603,6 +624,56 @@ impl Graph2 {
     Ok(())
   }
 
+  /// Given a string specifier and a referring module specifier, provide the
+  /// resulting module specifier and media type for the module that is part of
+  /// the graph.
+  pub fn resolve(
+    &self,
+    specifier: &str,
+    referrer: &ModuleSpecifier,
+  ) -> Result<ModuleSpecifier, AnyError> {
+    if !self.modules.contains_key(referrer) {
+      return Err(MissingSpecifier(referrer.to_owned()).into());
+    }
+    let module = self.modules.get(referrer).unwrap();
+    if !module.dependencies.contains_key(specifier) {
+      return Err(
+        MissingDependency(referrer.to_owned(), specifier.to_owned()).into(),
+      );
+    }
+    let dependency = module.dependencies.get(specifier).unwrap();
+    // If there is a @deno-types pragma that impacts the dependency, then the
+    // maybe_type property will be set with that specifier, otherwise we use the
+    // specifier that point to the runtime code.
+    let resolved_specifier =
+      if let Some(type_specifier) = dependency.maybe_type.clone() {
+        type_specifier
+      } else if let Some(code_specifier) = dependency.maybe_code.clone() {
+        code_specifier
+      } else {
+        return Err(
+          MissingDependency(referrer.to_owned(), specifier.to_owned()).into(),
+        );
+      };
+    if !self.modules.contains_key(&resolved_specifier) {
+      return Err(
+        MissingDependency(referrer.to_owned(), resolved_specifier.to_string())
+          .into(),
+      );
+    }
+    let dep_module = self.modules.get(&resolved_specifier).unwrap();
+    // In the case that there is a X-TypeScript-Types or a triple-slash types,
+    // then the `maybe_types` specifier will be populated and we should use that
+    // instead.
+    let result = if let Some((_, types)) = dep_module.maybe_types.clone() {
+      types
+    } else {
+      resolved_specifier
+    };
+
+    Ok(result)
+  }
+
   /// Transpile (only transform) the graph, updating any emitted modules
   /// with the specifier handler.  The result contains any performance stats
   /// from the compiler and optionally any user provided configuration compiler
@@ -807,7 +878,7 @@ impl GraphBuilder2 {
 }
 
 #[cfg(test)]
-mod tests {
+pub mod tests {
   use super::*;
 
   use deno_core::futures::future;
@@ -822,8 +893,8 @@ mod tests {
   #[derive(Debug, Default)]
   pub struct MockSpecifierHandler {
     pub fixtures: PathBuf,
-    pub build_info: HashMap<ModuleSpecifier, String>,
-    pub build_info_calls: Vec<(ModuleSpecifier, EmitType, String)>,
+    pub ts_build_info: HashMap<ModuleSpecifier, String>,
+    pub ts_build_info_calls: Vec<(ModuleSpecifier, EmitType, String)>,
     pub cache_calls: Vec<(ModuleSpecifier, EmitType, String, Option<String>)>,
     pub deps_calls: Vec<(ModuleSpecifier, DependencyMap)>,
     pub types_calls: Vec<(ModuleSpecifier, String)>,
@@ -871,12 +942,12 @@ mod tests {
     fn fetch(&mut self, specifier: ModuleSpecifier) -> FetchFuture {
       Box::pin(future::ready(self.get_cache(specifier)))
     }
-    fn get_build_info(
+    fn get_ts_build_info(
       &self,
       specifier: &ModuleSpecifier,
       _cache_type: &EmitType,
     ) -> Result<Option<String>, AnyError> {
-      Ok(self.build_info.get(specifier).cloned())
+      Ok(self.ts_build_info.get(specifier).cloned())
     }
     fn set_cache(
       &mut self,
@@ -901,19 +972,19 @@ mod tests {
       self.types_calls.push((specifier.clone(), types));
       Ok(())
     }
-    fn set_build_info(
+    fn set_ts_build_info(
       &mut self,
       specifier: &ModuleSpecifier,
       cache_type: &EmitType,
-      build_info: String,
+      ts_build_info: String,
     ) -> Result<(), AnyError> {
       self
-        .build_info
-        .insert(specifier.clone(), build_info.clone());
-      self.build_info_calls.push((
+        .ts_build_info
+        .insert(specifier.clone(), ts_build_info.clone());
+      self.ts_build_info_calls.push((
         specifier.clone(),
         cache_type.clone(),
-        build_info,
+        ts_build_info,
       ));
       Ok(())
     }
diff --git a/cli/specifier_handler.rs b/cli/specifier_handler.rs
index e392a3c3a8c6d5..9e070e106afbeb 100644
--- a/cli/specifier_handler.rs
+++ b/cli/specifier_handler.rs
@@ -100,7 +100,7 @@ pub trait SpecifierHandler {
   /// not expected to be cached for each module, but are "lazily" checked when
   /// a root module is identified.  The `emit_type` also indicates what form
   /// of the module the build info is valid for.
-  fn get_build_info(
+  fn get_ts_build_info(
     &self,
     specifier: &ModuleSpecifier,
     emit_type: &EmitType,
@@ -125,11 +125,11 @@ pub trait SpecifierHandler {
   ) -> Result<(), AnyError>;
 
   /// Set the build info for a module specifier, also providing the cache type.
-  fn set_build_info(
+  fn set_ts_build_info(
     &mut self,
     specifier: &ModuleSpecifier,
     emit_type: &EmitType,
-    build_info: String,
+    ts_build_info: String,
   ) -> Result<(), AnyError>;
 
   /// Set the graph dependencies for a given module specifier.
@@ -283,7 +283,7 @@ impl SpecifierHandler for FetchHandler {
     .boxed_local()
   }
 
-  fn get_build_info(
+  fn get_ts_build_info(
     &self,
     specifier: &ModuleSpecifier,
     emit_type: &EmitType,
@@ -294,18 +294,18 @@ impl SpecifierHandler for FetchHandler {
     let filename = self
       .disk_cache
       .get_cache_filename_with_extension(specifier.as_url(), "buildinfo");
-    if let Ok(build_info) = self.disk_cache.get(&filename) {
-      return Ok(Some(String::from_utf8(build_info)?));
+    if let Ok(ts_build_info) = self.disk_cache.get(&filename) {
+      return Ok(Some(String::from_utf8(ts_build_info)?));
     }
 
     Ok(None)
   }
 
-  fn set_build_info(
+  fn set_ts_build_info(
     &mut self,
     specifier: &ModuleSpecifier,
     emit_type: &EmitType,
-    build_info: String,
+    ts_build_info: String,
   ) -> Result<(), AnyError> {
     if emit_type != &EmitType::Cli {
       return Err(UnsupportedEmitType(emit_type.clone()).into());
@@ -315,7 +315,7 @@ impl SpecifierHandler for FetchHandler {
       .get_cache_filename_with_extension(specifier.as_url(), "buildinfo");
     self
       .disk_cache
-      .set(&filename, build_info.as_bytes())
+      .set(&filename, ts_build_info.as_bytes())
       .map_err(|e| e.into())
   }
 
diff --git a/cli/tests/tsc2/file_main.ts b/cli/tests/tsc2/file_main.ts
new file mode 100644
index 00000000000000..a45477fde6eb7a
--- /dev/null
+++ b/cli/tests/tsc2/file_main.ts
@@ -0,0 +1 @@
+console.log("hello deno");
diff --git a/cli/tests/tsc2/https_deno.land-x-a.ts b/cli/tests/tsc2/https_deno.land-x-a.ts
new file mode 100644
index 00000000000000..72b3a67bc98702
--- /dev/null
+++ b/cli/tests/tsc2/https_deno.land-x-a.ts
@@ -0,0 +1,3 @@
+import * as b from "./b.ts";
+
+console.log(b);
diff --git a/cli/tests/tsc2/https_deno.land-x-b.ts b/cli/tests/tsc2/https_deno.land-x-b.ts
new file mode 100644
index 00000000000000..59d1689930e55d
--- /dev/null
+++ b/cli/tests/tsc2/https_deno.land-x-b.ts
@@ -0,0 +1 @@
+export const b = "b";
diff --git a/cli/tests/tsc2/https_deno.land-x-mod.ts b/cli/tests/tsc2/https_deno.land-x-mod.ts
new file mode 100644
index 00000000000000..a45477fde6eb7a
--- /dev/null
+++ b/cli/tests/tsc2/https_deno.land-x-mod.ts
@@ -0,0 +1 @@
+console.log("hello deno");
diff --git a/cli/tsc.rs b/cli/tsc.rs
index aa83da280c0b48..56fc88bb4b55e8 100644
--- a/cli/tsc.rs
+++ b/cli/tsc.rs
@@ -417,7 +417,7 @@ impl TsCompiler {
         {
           let existing_hash = crate::checksum::gen(&[
             &source_file.source_code.as_bytes(),
-            version::DENO.as_bytes(),
+            &version::DENO.as_bytes(),
           ]);
           let expected_hash =
             file_info["version"].as_str().unwrap().to_string();
@@ -988,7 +988,7 @@ fn execute_in_tsc(
   }
 
   let bootstrap_script = format!(
-    "globalThis.bootstrapCompilerRuntime({{ debugFlag: {} }})",
+    "globalThis.startup({{ debugFlag: {}, legacy: true }})",
     debug_flag
   );
   js_runtime.execute("<compiler>", &bootstrap_script)?;
diff --git a/cli/tsc/99_main_compiler.js b/cli/tsc/99_main_compiler.js
index 7bb0c6c9229015..f05876e62d3fc2 100644
--- a/cli/tsc/99_main_compiler.js
+++ b/cli/tsc/99_main_compiler.js
@@ -4,7 +4,7 @@
 // that is created when Deno needs to compile TS/WASM to JS.
 //
 // It provides two functions that should be called by Rust:
-//  - `bootstrapCompilerRuntime`
+//  - `startup`
 // This functions must be called when creating isolate
 // to properly setup runtime.
 //  - `tsCompilerOnMessage`
@@ -54,6 +54,9 @@ delete Object.prototype.__proto__;
     }
   }
 
+  /** @type {Map<string, ts.SourceFile>} */
+  const sourceFileCache = new Map();
+
   /**
    * @param {import("../dts/typescript").DiagnosticRelatedInformation} diagnostic
    */
@@ -296,15 +299,15 @@ delete Object.prototype.__proto__;
       debug(`host.fileExists("${fileName}")`);
       return false;
     },
-    readFile(fileName) {
-      debug(`host.readFile("${fileName}")`);
+    readFile(specifier) {
+      debug(`host.readFile("${specifier}")`);
       if (legacy) {
-        if (fileName == TS_BUILD_INFO) {
+        if (specifier == TS_BUILD_INFO) {
           return legacyHostState.buildInfo;
         }
         return unreachable();
       } else {
-        return core.jsonOpSync("op_read_file", { fileName }).data;
+        return core.jsonOpSync("op_load", { specifier }).data;
       }
     },
     getSourceFile(
@@ -338,6 +341,14 @@ delete Object.prototype.__proto__;
             );
             sourceFile.tsSourceFile.version = sourceFile.versionHash;
             delete sourceFile.sourceCode;
+
+            // This code is to support transition from the "legacy" compiler
+            // to the new one, by populating the new source file cache.
+            if (
+              !sourceFileCache.has(specifier) && specifier.startsWith(ASSETS)
+            ) {
+              sourceFileCache.set(specifier, sourceFile.tsSourceFile);
+            }
           }
           return sourceFile.tsSourceFile;
         } catch (e) {
@@ -349,37 +360,27 @@ delete Object.prototype.__proto__;
           return undefined;
         }
       } else {
-        const sourceFile = sourceFileCache.get(specifier);
+        let sourceFile = sourceFileCache.get(specifier);
         if (sourceFile) {
           return sourceFile;
         }
 
-        try {
-          /** @type {{ data: string; hash: string; }} */
-          const { data, hash } = core.jsonOpSync(
-            "op_load_module",
-            { specifier },
-          );
-          const sourceFile = ts.createSourceFile(
-            specifier,
-            data,
-            languageVersion,
-          );
-          sourceFile.moduleName = specifier;
-          sourceFile.version = hash;
-          sourceFileCache.set(specifier, sourceFile);
-          return sourceFile;
-        } catch (err) {
-          const message = err instanceof Error
-            ? err.message
-            : JSON.stringify(err);
-          debug(`  !! error: ${message}`);
-          if (onError) {
-            onError(message);
-          } else {
-            throw err;
-          }
-        }
+        /** @type {{ data: string; hash: string; }} */
+        const { data, hash } = core.jsonOpSync(
+          "op_load",
+          { specifier },
+        );
+        debug({ data, hash });
+        assert(data, `"data" is unexpectedly null for "${specifier}".`);
+        sourceFile = ts.createSourceFile(
+          specifier,
+          data,
+          languageVersion,
+        );
+        sourceFile.moduleName = specifier;
+        sourceFile.version = hash;
+        sourceFileCache.set(specifier, sourceFile);
+        return sourceFile;
       }
     },
     getDefaultLibFileName() {
@@ -392,7 +393,7 @@ delete Object.prototype.__proto__;
             return `${ASSETS}/lib.deno.worker.d.ts`;
         }
       } else {
-        return `lib.esnext.d.ts`;
+        return `${ASSETS}/lib.esnext.d.ts`;
       }
     },
     getDefaultLibLocation() {
@@ -403,16 +404,14 @@ delete Object.prototype.__proto__;
       if (legacy) {
         legacyHostState.writeFile(fileName, data, sourceFiles);
       } else {
-        let maybeModuleName;
+        let maybeSpecifiers;
         if (sourceFiles) {
-          assert(sourceFiles.length === 1, "unexpected number of source files");
-          const [sourceFile] = sourceFiles;
-          maybeModuleName = sourceFile.moduleName;
-          debug(`  moduleName: ${maybeModuleName}`);
+          maybeSpecifiers = sourceFiles.map((sf) => sf.moduleName);
+          debug(`  specifiers: ${maybeSpecifiers.join(", ")}`);
         }
         return core.jsonOpSync(
-          "op_write_file",
-          { maybeModuleName, fileName, data },
+          "op_emit",
+          { maybeSpecifiers, fileName, data },
         );
       }
     },
@@ -463,7 +462,7 @@ delete Object.prototype.__proto__;
         return resolved;
       } else {
         /** @type {Array<[string, import("../dts/typescript").Extension]>} */
-        const resolved = core.jsonOpSync("op_resolve_specifiers", {
+        const resolved = core.jsonOpSync("op_resolve", {
           specifiers,
           base,
         });
@@ -737,6 +736,7 @@ delete Object.prototype.__proto__;
     1208,
   ];
 
+  /** @type {Array<{ key: string, value: number }>} */
   const stats = [];
   let statsStart = 0;
 
@@ -779,7 +779,6 @@ delete Object.prototype.__proto__;
   }
 
   function performanceEnd() {
-    // TODO(kitsonk) replace with performance.measure() when landed
     const duration = new Date() - statsStart;
     stats.push({ key: "Compile time", value: duration });
     return stats;
@@ -1328,18 +1327,73 @@ delete Object.prototype.__proto__;
     }
   }
 
-  let hasBootstrapped = false;
+  /**
+   * @typedef {object} Request
+   * @property {Record<string, any>} config
+   * @property {boolean} debug
+   * @property {string[]} rootNames
+   */
 
-  function bootstrapCompilerRuntime({ debugFlag }) {
-    if (hasBootstrapped) {
-      throw new Error("Worker runtime already bootstrapped");
+  /** The API that is called by Rust when executing a request.
+   * @param {Request} request 
+   */
+  function exec({ config, debug: debugFlag, rootNames }) {
+    setLogDebug(debugFlag, "TS");
+    performanceStart();
+    debug(">>> exec start", { rootNames });
+    debug(config);
+
+    const { options, errors: configFileParsingDiagnostics } = ts
+      .convertCompilerOptionsFromJson(config, "", "tsconfig.json");
+    const program = ts.createIncrementalProgram({
+      rootNames,
+      options,
+      host,
+      configFileParsingDiagnostics,
+    });
+
+    const { diagnostics: emitDiagnostics } = program.emit();
+
+    const diagnostics = [
+      ...program.getConfigFileParsingDiagnostics(),
+      ...program.getSyntacticDiagnostics(),
+      ...program.getOptionsDiagnostics(),
+      ...program.getGlobalDiagnostics(),
+      ...program.getSemanticDiagnostics(),
+      ...emitDiagnostics,
+    ].filter(({ code }) =>
+      !IGNORED_DIAGNOSTICS.includes(code) &&
+      !IGNORED_COMPILE_DIAGNOSTICS.includes(code)
+    );
+    performanceProgram({ program });
+
+    // TODO(@kitsonk) when legacy stats are removed, convert to just tuples
+    let stats = performanceEnd().map(({ key, value }) => [key, value]);
+    core.jsonOpSync("op_respond", {
+      diagnostics: fromTypeScriptDiagnostic(diagnostics),
+      stats,
+    });
+    debug("<<< exec stop");
+  }
+
+  let hasStarted = false;
+
+  /** Startup the runtime environment, setting various flags.
+   * @param {{ debugFlag?: boolean; legacyFlag?: boolean; }} msg 
+   */
+  function startup({ debugFlag = false, legacyFlag = true }) {
+    if (hasStarted) {
+      throw new Error("The compiler runtime already started.");
     }
-    hasBootstrapped = true;
-    delete globalThis.__bootstrap;
+    hasStarted = true;
     core.ops();
+    core.registerErrorClass("Error", Error);
     setLogDebug(!!debugFlag, "TS");
+    legacy = legacyFlag;
   }
 
-  globalThis.bootstrapCompilerRuntime = bootstrapCompilerRuntime;
+  globalThis.startup = startup;
+  globalThis.exec = exec;
+  // TODO(@kitsonk) remove when converted from legacy tsc
   globalThis.tsCompilerOnMessage = tsCompilerOnMessage;
 })(this);
diff --git a/cli/tsc2.rs b/cli/tsc2.rs
new file mode 100644
index 00000000000000..79ddab84d5aa4d
--- /dev/null
+++ b/cli/tsc2.rs
@@ -0,0 +1,571 @@
+// Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
+
+use crate::diagnostics::Diagnostics;
+use crate::media_type::MediaType;
+use crate::module_graph2::Graph2;
+use crate::module_graph2::Stats;
+use crate::tsc_config::TsConfig;
+
+use deno_core::error::anyhow;
+use deno_core::error::bail;
+use deno_core::error::AnyError;
+use deno_core::error::Context;
+use deno_core::json_op_sync;
+use deno_core::serde_json;
+use deno_core::serde_json::json;
+use deno_core::serde_json::Value;
+use deno_core::JsRuntime;
+use deno_core::ModuleSpecifier;
+use deno_core::OpFn;
+use deno_core::RuntimeOptions;
+use deno_core::Snapshot;
+use serde::Deserialize;
+use serde::Serialize;
+use std::cell::RefCell;
+use std::rc::Rc;
+
+#[derive(Debug, Clone, Default, Eq, PartialEq)]
+pub struct EmittedFile {
+  pub data: String,
+  pub maybe_specifiers: Option<Vec<ModuleSpecifier>>,
+  pub media_type: MediaType,
+}
+
+#[derive(Debug, Serialize)]
+#[serde(rename_all = "camelCase")]
+pub struct Request {
+  pub config: TsConfig,
+  pub debug: bool,
+  pub root_names: Vec<String>,
+}
+
+#[derive(Debug, Clone, Eq, PartialEq)]
+pub struct Response {
+  /// Any diagnostics that have been returned from the checker.
+  pub diagnostics: Diagnostics,
+  /// Any files that were emitted during the check.
+  pub emitted_files: Vec<EmittedFile>,
+  /// If there was any build info associated with the exec request.
+  pub maybe_tsbuildinfo: Option<String>,
+  /// Statistics from the check.
+  pub stats: Stats,
+}
+
+struct State {
+  hash_data: Vec<Vec<u8>>,
+  emitted_files: Vec<EmittedFile>,
+  graph: Rc<RefCell<Graph2>>,
+  maybe_tsbuildinfo: Option<String>,
+  maybe_response: Option<RespondArgs>,
+}
+
+impl State {
+  pub fn new(
+    graph: Rc<RefCell<Graph2>>,
+    hash_data: Vec<Vec<u8>>,
+    maybe_tsbuildinfo: Option<String>,
+  ) -> Self {
+    State {
+      hash_data,
+      emitted_files: Vec::new(),
+      graph,
+      maybe_tsbuildinfo,
+      maybe_response: None,
+    }
+  }
+}
+
+fn op<F>(op_fn: F) -> Box<OpFn>
+where
+  F: Fn(&mut State, Value) -> Result<Value, AnyError> + 'static,
+{
+  json_op_sync(move |s, args, _bufs| {
+    let state = s.borrow_mut::<State>();
+    op_fn(state, args)
+  })
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct CreateHashArgs {
+  /// The string data to be used to generate the hash.  This will be mixed with
+  /// other state data in Deno to derive the final hash.
+  data: String,
+}
+
+fn create_hash(state: &mut State, args: Value) -> Result<Value, AnyError> {
+  let v: CreateHashArgs = serde_json::from_value(args)
+    .context("Invalid request from JavaScript for \"op_create_hash\".")?;
+  let mut data = vec![v.data.as_bytes().to_owned()];
+  data.extend_from_slice(&state.hash_data);
+  let hash = crate::checksum::gen(&data);
+  Ok(json!({ "hash": hash }))
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct EmitArgs {
+  /// The text data/contents of the file.
+  data: String,
+  /// The _internal_ filename for the file.  This will be used to determine how
+  /// the file is cached and stored.
+  file_name: String,
+  /// A string representation of the specifier that was associated with a
+  /// module.  This should be present on every module that represents a module
+  /// that was requested to be transformed.
+  maybe_specifiers: Option<Vec<String>>,
+}
+
+fn emit(state: &mut State, args: Value) -> Result<Value, AnyError> {
+  let v: EmitArgs = serde_json::from_value(args)
+    .context("Invalid request from JavaScript for \"op_emit\".")?;
+  match v.file_name.as_ref() {
+    "deno:///.tsbuildinfo" => state.maybe_tsbuildinfo = Some(v.data),
+    _ => state.emitted_files.push(EmittedFile {
+      data: v.data,
+      maybe_specifiers: if let Some(specifiers) = &v.maybe_specifiers {
+        let specifiers = specifiers
+          .iter()
+          .map(|s| ModuleSpecifier::resolve_url_or_path(s).unwrap())
+          .collect();
+        Some(specifiers)
+      } else {
+        None
+      },
+      media_type: MediaType::from(&v.file_name),
+    }),
+  }
+
+  Ok(json!(true))
+}
+
+#[derive(Debug, Deserialize)]
+struct LoadArgs {
+  /// The fully qualified specifier that should be loaded.
+  specifier: String,
+}
+
+fn load(state: &mut State, args: Value) -> Result<Value, AnyError> {
+  let v: LoadArgs = serde_json::from_value(args)
+    .context("Invalid request from JavaScript for \"op_load\".")?;
+  let graph = state.graph.borrow();
+  let specifier = ModuleSpecifier::resolve_url_or_path(&v.specifier)
+    .context("Error converting a string module specifier for \"op_load\".")?;
+  let mut hash: Option<String> = None;
+  let data = if &v.specifier == "deno:///.tsbuildinfo" {
+    state.maybe_tsbuildinfo.clone()
+  } else {
+    let maybe_source = graph.get_source(&specifier);
+    if let Some(source) = &maybe_source {
+      let mut data = vec![source.as_bytes().to_owned()];
+      data.extend_from_slice(&state.hash_data);
+      hash = Some(crate::checksum::gen(&data));
+    }
+    maybe_source
+  };
+
+  Ok(json!({ "data": data, "hash": hash }))
+}
+
+#[derive(Debug, Deserialize)]
+#[serde(rename_all = "camelCase")]
+struct ResolveArgs {
+  /// The base specifier that the supplied specifier strings should be resolved
+  /// relative to.
+  base: String,
+  /// A list of specifiers that should be resolved.
+  specifiers: Vec<String>,
+}
+
+fn resolve(state: &mut State, args: Value) -> Result<Value, AnyError> {
+  let v: ResolveArgs = serde_json::from_value(args)
+    .context("Invalid request from JavaScript for \"op_resolve\".")?;
+  let graph = state.graph.borrow();
+  let mut resolved: Vec<(String, String)> = Vec::new();
+  let referrer = ModuleSpecifier::resolve_url_or_path(&v.base).context(
+    "Error converting a string module specifier for \"op_resolve\".",
+  )?;
+  for specifier in &v.specifiers {
+    if specifier.starts_with("asset:///") {
+      resolved.push((
+        specifier.clone(),
+        MediaType::from(specifier).as_ts_extension().to_string(),
+      ));
+    } else {
+      let resolved_specifier = graph.resolve(specifier, &referrer)?;
+      let media_type =
+        if let Some(media_type) = graph.get_media_type(&resolved_specifier) {
+          media_type
+        } else {
+          bail!(
+            "Unable to resolve media type for specifier: \"{}\"",
+            resolved_specifier
+          )
+        };
+      resolved
+        .push((resolved_specifier.to_string(), media_type.as_ts_extension()));
+    }
+  }
+
+  Ok(json!(resolved))
+}
+
+#[derive(Debug, Deserialize, Eq, PartialEq)]
+pub struct RespondArgs {
+  pub diagnostics: Diagnostics,
+  pub stats: Stats,
+}
+
+fn respond(state: &mut State, args: Value) -> Result<Value, AnyError> {
+  let v: RespondArgs = serde_json::from_value(args)
+    .context("Error converting the result for \"op_respond\".")?;
+  state.maybe_response = Some(v);
+  Ok(json!(true))
+}
+
+pub fn exec(
+  request: Request,
+  snapshot: Snapshot,
+  graph: Rc<RefCell<Graph2>>,
+  hash_data: Vec<Vec<u8>>,
+  maybe_tsbuildinfo: Option<String>,
+) -> Result<Response, AnyError> {
+  let mut runtime = JsRuntime::new(RuntimeOptions {
+    startup_snapshot: Some(snapshot),
+    ..Default::default()
+  });
+
+  {
+    let op_state = runtime.op_state();
+    let mut op_state = op_state.borrow_mut();
+    op_state.put(State::new(graph, hash_data, maybe_tsbuildinfo));
+  }
+
+  runtime.register_op("op_create_hash", op(create_hash));
+  runtime.register_op("op_emit", op(emit));
+  runtime.register_op("op_load", op(load));
+  runtime.register_op("op_resolve", op(resolve));
+  runtime.register_op("op_respond", op(respond));
+
+  let startup_source = "globalThis.startup({ legacyFlag: false })";
+  let request_str =
+    serde_json::to_string(&request).context("Could not serialize request.")?;
+  let exec_source = format!("globalThis.exec({})", request_str);
+
+  runtime
+    .execute("[native code]", startup_source)
+    .context("Could not properly start the compiler runtime.")?;
+  runtime
+    .execute("[native_code]", &exec_source)
+    .context("Execute request failed.")?;
+
+  let op_state = runtime.op_state();
+  let mut op_state = op_state.borrow_mut();
+  let state = op_state.take::<State>();
+
+  if let Some(response) = state.maybe_response {
+    let diagnostics = response.diagnostics;
+    let emitted_files = state.emitted_files;
+    let maybe_tsbuildinfo = state.maybe_tsbuildinfo;
+    let stats = response.stats;
+
+    Ok(Response {
+      diagnostics,
+      emitted_files,
+      maybe_tsbuildinfo,
+      stats,
+    })
+  } else {
+    Err(anyhow!("The response for the exec request was not set."))
+  }
+}
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+  use crate::diagnostics::Diagnostic;
+  use crate::diagnostics::DiagnosticCategory;
+  use crate::js;
+  use crate::module_graph2::tests::MockSpecifierHandler;
+  use crate::module_graph2::GraphBuilder2;
+  use crate::tsc_config::TsConfig;
+  use std::env;
+  use std::path::PathBuf;
+
+  async fn setup(
+    maybe_specifier: Option<ModuleSpecifier>,
+    maybe_hash_data: Option<Vec<Vec<u8>>>,
+    maybe_tsbuildinfo: Option<String>,
+  ) -> State {
+    let specifier = maybe_specifier.unwrap_or_else(|| {
+      ModuleSpecifier::resolve_url_or_path("file:///main.ts").unwrap()
+    });
+    let hash_data = maybe_hash_data.unwrap_or_else(|| vec![b"".to_vec()]);
+    let c = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
+    let fixtures = c.join("tests/tsc2");
+    let handler = Rc::new(RefCell::new(MockSpecifierHandler {
+      fixtures,
+      ..MockSpecifierHandler::default()
+    }));
+    let mut builder = GraphBuilder2::new(handler.clone(), None);
+    builder
+      .insert(&specifier)
+      .await
+      .expect("module not inserted");
+    let graph = Rc::new(RefCell::new(
+      builder.get_graph(&None).expect("could not get graph"),
+    ));
+    State::new(graph, hash_data, maybe_tsbuildinfo)
+  }
+
+  #[tokio::test]
+  async fn test_create_hash() {
+    let mut state = setup(None, Some(vec![b"something".to_vec()]), None).await;
+    let actual =
+      create_hash(&mut state, json!({ "data": "some sort of content" }))
+        .expect("could not invoke op");
+    assert_eq!(
+      actual,
+      json!({"hash": "ae92df8f104748768838916857a1623b6a3c593110131b0a00f81ad9dac16511"})
+    );
+  }
+
+  #[tokio::test]
+  async fn test_emit() {
+    let mut state = setup(None, None, None).await;
+    let actual = emit(
+      &mut state,
+      json!({
+        "data": "some file content",
+        "fileName": "cache:///some/file.js",
+        "maybeSpecifiers": ["file:///some/file.ts"]
+      }),
+    )
+    .expect("should have invoked op");
+    assert_eq!(actual, json!(true));
+    assert_eq!(state.emitted_files.len(), 1);
+    assert!(state.maybe_tsbuildinfo.is_none());
+    assert_eq!(
+      state.emitted_files[0],
+      EmittedFile {
+        data: "some file content".to_string(),
+        maybe_specifiers: Some(vec![ModuleSpecifier::resolve_url_or_path(
+          "file:///some/file.ts"
+        )
+        .unwrap()]),
+        media_type: MediaType::JavaScript,
+      }
+    );
+  }
+
+  #[tokio::test]
+  async fn test_emit_tsbuildinfo() {
+    let mut state = setup(None, None, None).await;
+    let actual = emit(
+      &mut state,
+      json!({
+        "data": "some file content",
+        "fileName": "deno:///.tsbuildinfo",
+      }),
+    )
+    .expect("should have invoked op");
+    assert_eq!(actual, json!(true));
+    assert_eq!(state.emitted_files.len(), 0);
+    assert_eq!(
+      state.maybe_tsbuildinfo,
+      Some("some file content".to_string())
+    );
+  }
+
+  #[tokio::test]
+  async fn test_load() {
+    let mut state = setup(
+      Some(
+        ModuleSpecifier::resolve_url_or_path("https://deno.land/x/mod.ts")
+          .unwrap(),
+      ),
+      None,
+      Some("some content".to_string()),
+    )
+    .await;
+    let actual = load(
+      &mut state,
+      json!({ "specifier": "https://deno.land/x/mod.ts"}),
+    )
+    .expect("should have invoked op");
+    assert_eq!(
+      actual,
+      json!({
+        "data": "console.log(\"hello deno\");\n",
+        "hash": "149c777056afcc973d5fcbe11421b6d5ddc57b81786765302030d7fc893bf729"
+      })
+    );
+  }
+
+  #[tokio::test]
+  async fn test_load_tsbuildinfo() {
+    let mut state = setup(
+      Some(
+        ModuleSpecifier::resolve_url_or_path("https://deno.land/x/mod.ts")
+          .unwrap(),
+      ),
+      None,
+      Some("some content".to_string()),
+    )
+    .await;
+    let actual =
+      load(&mut state, json!({ "specifier": "deno:///.tsbuildinfo"}))
+        .expect("should have invoked op");
+    assert_eq!(
+      actual,
+      json!({
+        "data": "some content",
+        "hash": null
+      })
+    );
+  }
+
+  #[tokio::test]
+  async fn test_load_missing_specifier() {
+    let mut state = setup(None, None, None).await;
+    let actual = load(
+      &mut state,
+      json!({ "specifier": "https://deno.land/x/mod.ts"}),
+    )
+    .expect("should have invoked op");
+    assert_eq!(
+      actual,
+      json!({
+        "data": null,
+        "hash": null,
+      })
+    )
+  }
+
+  #[tokio::test]
+  async fn test_resolve() {
+    let mut state = setup(
+      Some(
+        ModuleSpecifier::resolve_url_or_path("https://deno.land/x/a.ts")
+          .unwrap(),
+      ),
+      None,
+      None,
+    )
+    .await;
+    let actual = resolve(
+      &mut state,
+      json!({ "base": "https://deno.land/x/a.ts", "specifiers": [ "./b.ts" ]}),
+    )
+    .expect("should have invoked op");
+    assert_eq!(actual, json!([["https://deno.land/x/b.ts", ".ts"]]));
+  }
+
+  #[tokio::test]
+  async fn test_resolve_error() {
+    let mut state = setup(
+      Some(
+        ModuleSpecifier::resolve_url_or_path("https://deno.land/x/a.ts")
+          .unwrap(),
+      ),
+      None,
+      None,
+    )
+    .await;
+    resolve(
+      &mut state,
+      json!({ "base": "https://deno.land/x/a.ts", "specifiers": [ "./bad.ts" ]}),
+    ).expect_err("should have errored");
+  }
+
+  #[tokio::test]
+  async fn test_respond() {
+    let mut state = setup(None, None, None).await;
+    let actual = respond(
+      &mut state,
+      json!({
+        "diagnostics": [
+          {
+            "messageText": "Unknown compiler option 'invalid'.",
+            "category": 1,
+            "code": 5023
+          }
+        ],
+        "stats": [["a", 12]]
+      }),
+    )
+    .expect("should have invoked op");
+    assert_eq!(actual, json!(true));
+    assert_eq!(
+      state.maybe_response,
+      Some(RespondArgs {
+        diagnostics: Diagnostics(vec![Diagnostic {
+          category: DiagnosticCategory::Error,
+          code: 5023,
+          start: None,
+          end: None,
+          message_text: Some(
+            "Unknown compiler option \'invalid\'.".to_string()
+          ),
+          message_chain: None,
+          source: None,
+          source_line: None,
+          file_name: None,
+          related_information: None,
+        }]),
+        stats: Stats(vec![("a".to_string(), 12)])
+      })
+    );
+  }
+
+  #[tokio::test]
+  async fn test_exec() {
+    let specifier =
+      ModuleSpecifier::resolve_url_or_path("https://deno.land/x/a.ts").unwrap();
+    let hash_data = vec![b"something".to_vec()];
+    let c = PathBuf::from(env::var_os("CARGO_MANIFEST_DIR").unwrap());
+    let fixtures = c.join("tests/tsc2");
+    let handler = Rc::new(RefCell::new(MockSpecifierHandler {
+      fixtures,
+      ..MockSpecifierHandler::default()
+    }));
+    let mut builder = GraphBuilder2::new(handler.clone(), None);
+    builder
+      .insert(&specifier)
+      .await
+      .expect("module not inserted");
+    let graph = Rc::new(RefCell::new(
+      builder.get_graph(&None).expect("could not get graph"),
+    ));
+    let config = TsConfig::new(json!({
+      "allowJs": true,
+      "checkJs": false,
+      "esModuleInterop": true,
+      "emitDecoratorMetadata": false,
+      "incremental": true,
+      "isolatedModules": true,
+      "jsx": "react",
+      "jsxFactory": "React.createElement",
+      "jsxFragmentFactory": "React.Fragment",
+      "lib": ["deno.window"],
+      "module": "esnext",
+      "noEmit": true,
+      "outDir": "deno:///",
+      "strict": true,
+      "target": "esnext",
+      "tsBuildInfoFile": "deno:///.tsbuildinfo",
+    }));
+    let request = Request {
+      config,
+      debug: true,
+      root_names: vec!["https://deno.land/x/a.ts".to_string()],
+    };
+    let actual =
+      exec(request, js::compiler_isolate_init(), graph, hash_data, None)
+        .expect("exec should have not errored");
+    assert!(actual.diagnostics.0.is_empty());
+    assert!(actual.emitted_files.is_empty());
+    assert!(actual.maybe_tsbuildinfo.is_some());
+    assert_eq!(actual.stats.0.len(), 12);
+  }
+}
diff --git a/core/error.rs b/core/error.rs
index 8a80e30246543a..7f16af6c125bdf 100644
--- a/core/error.rs
+++ b/core/error.rs
@@ -1,5 +1,8 @@
 // Copyright 2018-2020 the Deno authors. All rights reserved. MIT license.
 
+pub use anyhow::anyhow;
+pub use anyhow::bail;
+pub use anyhow::Context;
 use rusty_v8 as v8;
 use std::borrow::Cow;
 use std::convert::TryFrom;