From 6bd7fe1154f944d33d8a8ab2ecbf480ec3d496c0 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Dandelion=20Man=C3=A9?= <decentralion@dandelion.io>
Date: Sun, 21 Jul 2019 16:05:21 +0100
Subject: [PATCH] Replace `Object.freeze` with `deepFreeze`

Throughout the codebase, we freeze objects when we want to ensure that
their properties are never altered -- e.g. because they are a plugin
declaration, or are being re-used for various test cases.

We generally use `Object.freeze`. This has the disadvantage that it does
not work recursively, so a frozen object's mutable fields and properties
can still be mutated. (E.g. if `const obj = Object.freeze({foo: []})`,
then `obj.foo.push(1)` will succeed in mutating the 'frozen' object).

Sometimes we anticipate this and explicitly freeze the sub-fields (which
is tedious); sometimes we forget (which invites errors). This change
simply replaces all instances of Object.freeze with [deep-freeze], so we
don't need to worry about the issue at all anymore.

Test plan: `yarn test` passes (after updating snapshots);
`git grep Object.freeze` returns no hits.

[deep-freeze]: https://www.npmjs.com/package/deep-freeze
---
 package.json                                  |  1 +
 src/analysis/loadGraph.test.js                | 16 ++++----
 src/analysis/timeline/timelinePagerank.js     |  3 +-
 src/analysis/weightEvaluator.test.js          | 19 +++++----
 src/analysis/weightsToEdgeEvaluator.test.js   |  9 ++--
 src/cli/common.js                             |  3 +-
 src/core/address.js                           |  3 +-
 src/core/graph.js                             |  3 +-
 src/core/graphTestUtil.js                     |  8 ++--
 src/core/project.test.js                      | 13 +++---
 src/core/project_io.test.js                   | 13 +++---
 src/core/version.js                           |  6 ++-
 .../legacy/pagerankTable/aggregate.js         |  7 ++--
 .../generateFlowTypes.test.js.snap            |  6 ++-
 src/graphql/generateFlowTypes.js              |  5 ++-
 src/graphql/mirror.js                         |  3 +-
 src/plugins/defaultCredConfig.js              | 15 +++----
 src/plugins/demo/declaration.js               | 18 ++++----
 src/plugins/demo/graph.js                     |  5 ++-
 src/plugins/git/declaration.js                | 11 ++---
 src/plugins/git/edges.js                      |  5 ++-
 src/plugins/git/mergeRepository.test.js       |  9 ++--
 src/plugins/git/nodes.js                      |  3 +-
 src/plugins/git/render.test.js                |  5 ++-
 src/plugins/github/blacklistedObjectIds.js    |  3 +-
 src/plugins/github/declaration.js             | 41 ++++++++++---------
 src/plugins/github/edges.js                   |  5 ++-
 src/plugins/github/graphqlTypes.js            |  6 ++-
 src/plugins/github/nodes.js                   |  3 +-
 src/webutil/Colors.js                         | 11 ++---
 yarn.lock                                     |  5 +++
 31 files changed, 150 insertions(+), 113 deletions(-)

diff --git a/package.json b/package.json
index 3feb0a0..26e245f 100644
--- a/package.json
+++ b/package.json
@@ -14,6 +14,7 @@
     "d3-scale-chromatic": "^1.3.3",
     "d3-time": "^1.0.11",
     "d3-time-format": "^2.1.3",
+    "deep-freeze": "^0.0.1",
     "express": "^4.16.3",
     "fs-extra": "8.1.0",
     "history": "^3.0.0",
diff --git a/src/analysis/loadGraph.test.js b/src/analysis/loadGraph.test.js
index e87886b..b8a80f2 100644
--- a/src/analysis/loadGraph.test.js
+++ b/src/analysis/loadGraph.test.js
@@ -2,6 +2,7 @@
 
 import tmp from "tmp";
 import path from "path";
+import deepFreeze from "deep-freeze";
 
 import {
   Graph,
@@ -18,13 +19,14 @@ import {makeRepoId, type RepoId} from "../core/repoId";
 import {loadGraph} from "./loadGraph";
 import {node} from "../core/graphTestUtil";
 
-const declaration = (name) => ({
-  name,
-  nodePrefix: NodeAddress.empty,
-  edgePrefix: EdgeAddress.empty,
-  nodeTypes: Object.freeze([]),
-  edgeTypes: Object.freeze([]),
-});
+const declaration = (name) =>
+  deepFreeze({
+    name,
+    nodePrefix: NodeAddress.empty,
+    edgePrefix: EdgeAddress.empty,
+    nodeTypes: [],
+    edgeTypes: [],
+  });
 
 class MockStaticAdapter implements IBackendAdapterLoader {
   _resolutionGraph: ?Graph;
diff --git a/src/analysis/timeline/timelinePagerank.js b/src/analysis/timeline/timelinePagerank.js
index f7a42ca..754bc55 100644
--- a/src/analysis/timeline/timelinePagerank.js
+++ b/src/analysis/timeline/timelinePagerank.js
@@ -3,6 +3,7 @@
 /**
  * Core logic for computing timeline PageRank on a graph.
  */
+import deepFreeze from "deep-freeze";
 import {sum} from "d3-array";
 import * as NullUtil from "../../util/null";
 import {Graph, type NodeAddressT, type Edge, type Node} from "../../core/graph";
@@ -183,7 +184,7 @@ export function* _timelineMarkovChain(
     for (const {address} of edges) {
       edgeWeights.set(address, edgeEvaluator(address));
     }
-    const defaultEdgeWeight = Object.freeze({forwards: 0, backwards: 0});
+    const defaultEdgeWeight = deepFreeze({forwards: 0, backwards: 0});
     const currentEdgeWeight = (e: Edge) => {
       return NullUtil.orElse(edgeWeights.get(e.address), defaultEdgeWeight);
     };
diff --git a/src/analysis/weightEvaluator.test.js b/src/analysis/weightEvaluator.test.js
index 5b3b217..b967c02 100644
--- a/src/analysis/weightEvaluator.test.js
+++ b/src/analysis/weightEvaluator.test.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {NodeAddress, EdgeAddress} from "../core/graph";
 import {nodeWeightEvaluator, edgeWeightEvaluator} from "./weightEvaluator";
 import {defaultWeights} from "./weights";
@@ -10,7 +11,7 @@ describe("src/analysis/weightEvaluator", () => {
     const foo = NodeAddress.fromParts(["foo"]);
     const foobar = NodeAddress.fromParts(["foo", "bar"]);
 
-    const fooNodeType = Object.freeze({
+    const fooNodeType = deepFreeze({
       name: "",
       pluralName: "",
       prefix: foo,
@@ -18,7 +19,7 @@ describe("src/analysis/weightEvaluator", () => {
       description: "",
     });
 
-    const fooBarNodeType = Object.freeze({
+    const fooBarNodeType = deepFreeze({
       name: "",
       pluralName: "",
       prefix: foobar,
@@ -26,7 +27,7 @@ describe("src/analysis/weightEvaluator", () => {
       description: "",
     });
 
-    const types = Object.freeze([fooNodeType, fooBarNodeType]);
+    const types = deepFreeze([fooNodeType, fooBarNodeType]);
 
     it("gives every node weight 1 with empty types and weights", () => {
       const evaluator = nodeWeightEvaluator([], defaultWeights());
@@ -69,20 +70,20 @@ describe("src/analysis/weightEvaluator", () => {
   describe("edgeEvaluator", () => {
     const foo = EdgeAddress.fromParts(["foo"]);
     const foobar = EdgeAddress.fromParts(["foo", "bar"]);
-    const fooType = {
+    const fooType = deepFreeze({
       forwardName: "",
       backwardName: "",
-      defaultWeight: Object.freeze({forwards: 2, backwards: 3}),
+      defaultWeight: {forwards: 2, backwards: 3},
       prefix: foo,
       description: "",
-    };
-    const fooBarType = {
+    });
+    const fooBarType = deepFreeze({
       forwardName: "",
       backwardName: "",
-      defaultWeight: Object.freeze({forwards: 4, backwards: 5}),
+      defaultWeight: {forwards: 4, backwards: 5},
       prefix: foobar,
       description: "",
-    };
+    });
     it("gives default 1,1 weights if no matching type", () => {
       const evaluator = edgeWeightEvaluator([], defaultWeights());
       expect(evaluator(foo)).toEqual({forwards: 1, backwards: 1});
diff --git a/src/analysis/weightsToEdgeEvaluator.test.js b/src/analysis/weightsToEdgeEvaluator.test.js
index dcf0f61..a27feb7 100644
--- a/src/analysis/weightsToEdgeEvaluator.test.js
+++ b/src/analysis/weightsToEdgeEvaluator.test.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {NodeAddress, EdgeAddress} from "../core/graph";
 import {type Weights, defaultWeights} from "./weights";
 import {weightsToEdgeEvaluator} from "./weightsToEdgeEvaluator";
@@ -14,7 +15,7 @@ describe("analysis/weightsToEdgeEvaluator", () => {
     timestampMs: 0,
   };
 
-  const fallbackNodeType = Object.freeze({
+  const fallbackNodeType = deepFreeze({
     name: "",
     pluralName: "",
     prefix: NodeAddress.empty,
@@ -22,7 +23,7 @@ describe("analysis/weightsToEdgeEvaluator", () => {
     description: "",
   });
 
-  const srcNodeType = Object.freeze({
+  const srcNodeType = deepFreeze({
     name: "",
     pluralName: "",
     prefix: src,
@@ -30,10 +31,10 @@ describe("analysis/weightsToEdgeEvaluator", () => {
     description: "",
   });
 
-  const fallbackEdgeType = Object.freeze({
+  const fallbackEdgeType = deepFreeze({
     forwardName: "",
     backwardName: "",
-    defaultWeight: Object.freeze({forwards: 1, backwards: 1}),
+    defaultWeight: {forwards: 1, backwards: 1},
     prefix: EdgeAddress.empty,
     description: "",
   });
diff --git a/src/cli/common.js b/src/cli/common.js
index 0a73229..b81840f 100644
--- a/src/cli/common.js
+++ b/src/cli/common.js
@@ -3,12 +3,13 @@
 
 import os from "os";
 import path from "path";
+import deepFreeze from "deep-freeze";
 
 import * as NullUtil from "../util/null";
 
 export type PluginName = "git" | "github";
 
-export const defaultPlugins: PluginName[] = Object.freeze(["github"]);
+export const defaultPlugins: PluginName[] = deepFreeze(["github"]);
 
 export function defaultSourcecredDirectory() {
   return path.join(os.tmpdir(), "sourcecred");
diff --git a/src/core/address.js b/src/core/address.js
index 8171d5f..c80f705 100644
--- a/src/core/address.js
+++ b/src/core/address.js
@@ -1,6 +1,7 @@
 // @flow
 
 import stringify from "json-stable-stringify";
+import deepFreeze from "deep-freeze";
 
 import * as MapUtil from "../util/map";
 
@@ -233,5 +234,5 @@ export function makeAddressModule(options: Options): AddressModule<string> {
     append,
     hasPrefix,
   };
-  return Object.freeze(result);
+  return deepFreeze(result);
 }
diff --git a/src/core/graph.js b/src/core/graph.js
index 3ba5b81..fddc611 100644
--- a/src/core/graph.js
+++ b/src/core/graph.js
@@ -1,6 +1,7 @@
 // @flow
 
 import deepEqual from "lodash.isequal";
+import deepFreeze from "deep-freeze";
 
 import {makeAddressModule, type AddressModule} from "./address";
 import {toCompat, fromCompat, type Compatible} from "../util/compat";
@@ -151,7 +152,7 @@ export const Direction: {|
   +IN: DirectionT,
   +OUT: DirectionT,
   +ANY: DirectionT,
-|} = Object.freeze({
+|} = deepFreeze({
   IN: Symbol("IN"),
   OUT: Symbol("OUT"),
   ANY: Symbol("ANY"),
diff --git a/src/core/graphTestUtil.js b/src/core/graphTestUtil.js
index cff3b1e..4f1e885 100644
--- a/src/core/graphTestUtil.js
+++ b/src/core/graphTestUtil.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {EdgeAddress, Graph, NodeAddress, type Node, type Edge} from "./graph";
 
 /**
@@ -12,11 +13,10 @@ import {EdgeAddress, Graph, NodeAddress, type Node, type Edge} from "./graph";
  * the codebase.
  *
  * The returned node is frozen; as such, it is safe to re-use this exact
- * object across test cases. If any non-primitive field is added to Node,
- * please ensure this function freezes that field explicitly.
+ * object across test cases.
  */
 export function partsNode(parts: string[]): Node {
-  return Object.freeze({
+  return deepFreeze({
     address: NodeAddress.fromParts(parts),
     description: parts.toString(),
     timestampMs: null,
@@ -40,7 +40,7 @@ export function node(name: string): Node {
  * The returned edge is frozen, so it is safe to use across test cases.
  */
 export function partsEdge(parts: string[], src: Node, dst: Node): Edge {
-  return Object.freeze({
+  return deepFreeze({
     address: EdgeAddress.fromParts(parts),
     src: src.address,
     dst: dst.address,
diff --git a/src/core/project.test.js b/src/core/project.test.js
index 982b1d4..4baf6d4 100644
--- a/src/core/project.test.js
+++ b/src/core/project.test.js
@@ -1,6 +1,7 @@
 // @flow
 
 import base64url from "base64url";
+import deepFreeze from "deep-freeze";
 import {
   projectToJSON,
   projectFromJSON,
@@ -11,15 +12,15 @@ import {
 import {makeRepoId} from "./repoId";
 
 describe("core/project", () => {
-  const foobar = Object.freeze(makeRepoId("foo", "bar"));
-  const foozod = Object.freeze(makeRepoId("foo", "zod"));
-  const p1: Project = Object.freeze({
+  const foobar = deepFreeze(makeRepoId("foo", "bar"));
+  const foozod = deepFreeze(makeRepoId("foo", "zod"));
+  const p1: Project = deepFreeze({
     id: "foo/bar",
-    repoIds: Object.freeze([foobar]),
+    repoIds: [foobar],
   });
-  const p2: Project = Object.freeze({
+  const p2: Project = deepFreeze({
     id: "@foo",
-    repoIds: Object.freeze([foobar, foozod]),
+    repoIds: [foobar, foozod],
   });
   describe("to/fro JSON", () => {
     it("round trip is identity", () => {
diff --git a/src/core/project_io.test.js b/src/core/project_io.test.js
index 5601fe3..1be7655 100644
--- a/src/core/project_io.test.js
+++ b/src/core/project_io.test.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import tmp from "tmp";
 import path from "path";
 import fs from "fs-extra";
@@ -16,15 +17,15 @@ import {
 import {makeRepoId} from "./repoId";
 
 describe("core/project_io", () => {
-  const foobar = Object.freeze(makeRepoId("foo", "bar"));
-  const foozod = Object.freeze(makeRepoId("foo", "zod"));
-  const p1: Project = Object.freeze({
+  const foobar = deepFreeze(makeRepoId("foo", "bar"));
+  const foozod = deepFreeze(makeRepoId("foo", "zod"));
+  const p1: Project = deepFreeze({
     id: "foo/bar",
-    repoIds: Object.freeze([foobar]),
+    repoIds: [foobar],
   });
-  const p2: Project = Object.freeze({
+  const p2: Project = deepFreeze({
     id: "@foo",
-    repoIds: Object.freeze([foobar, foozod]),
+    repoIds: [foobar, foozod],
   });
 
   it("setupProjectDirectory results in a loadable project", async () => {
diff --git a/src/core/version.js b/src/core/version.js
index 6bef850..59f024e 100644
--- a/src/core/version.js
+++ b/src/core/version.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 export type VersionInfo = {|
   +major: number,
   +minor: number,
@@ -24,10 +25,11 @@ export function parseGitState(raw: ?string): GitState {
   if (typeof raw !== "string") {
     throw new Error("gitState: not a string: " + String(raw));
   }
-  const parsed: mixed = Object.freeze(JSON.parse(raw));
+  const parsed: mixed = JSON.parse(raw);
   if (parsed == null || typeof parsed !== "object") {
     throw new Error("gitState: not a JSON object: " + String(parsed));
   }
+  deepFreeze(parsed);
   // This intermediate variable helps out Flow's inference...
   const gitState: Object = parsed;
   if (
@@ -56,7 +58,7 @@ export function parseEnvironment(raw: ?string): Environment {
 }
 const environment = parseEnvironment(process.env.NODE_ENV);
 
-export const VERSION_INFO: VersionInfo = Object.freeze({
+export const VERSION_INFO: VersionInfo = deepFreeze({
   major: 0,
   minor: 3,
   patch: 0,
diff --git a/src/explorer/legacy/pagerankTable/aggregate.js b/src/explorer/legacy/pagerankTable/aggregate.js
index 32ff47b..9fea9e7 100644
--- a/src/explorer/legacy/pagerankTable/aggregate.js
+++ b/src/explorer/legacy/pagerankTable/aggregate.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import sortBy from "lodash.sortby";
 import stringify from "json-stable-stringify";
 import * as MapUtil from "../../../util/map";
@@ -45,7 +46,7 @@ export type FlatAggregation = {|
   +connections: $ReadOnlyArray<ScoredConnection>,
 |};
 
-export const fallbackNodeType: NodeType = Object.freeze({
+export const fallbackNodeType: NodeType = deepFreeze({
   name: "node",
   pluralName: "nodes",
   prefix: NodeAddress.empty,
@@ -53,10 +54,10 @@ export const fallbackNodeType: NodeType = Object.freeze({
   description: "",
 });
 
-export const fallbackEdgeType: EdgeType = Object.freeze({
+export const fallbackEdgeType: EdgeType = deepFreeze({
   forwardName: "has edge to",
   backwardName: "has edge from",
-  defaultWeight: Object.freeze({forwards: 1, backwards: 1}),
+  defaultWeight: {forwards: 1, backwards: 1},
   prefix: EdgeAddress.empty,
   description: "",
 });
diff --git a/src/graphql/__snapshots__/generateFlowTypes.test.js.snap b/src/graphql/__snapshots__/generateFlowTypes.test.js.snap
index cc3d22e..4ef9745 100644
--- a/src/graphql/__snapshots__/generateFlowTypes.test.js.snap
+++ b/src/graphql/__snapshots__/generateFlowTypes.test.js.snap
@@ -5,6 +5,8 @@ exports[`graphql/generateFlowTypes generateFlowTypes works on a representative s
 
 // Autogenerated file. Do not edit.
 
+import deepFreeze from \\"deep-freeze\\";
+
 export type Actor = Human | TalentedChimpanzee;
 
 export type Color = \\"BLUE\\" | \\"GREEN\\" | \\"RED\\";
@@ -13,7 +15,7 @@ export const Color$Values: {|
   +BLUE: \\"BLUE\\",
   +GREEN: \\"GREEN\\",
   +RED: \\"RED\\",
-|} = Object.freeze({ BLUE: \\"BLUE\\", GREEN: \\"GREEN\\", RED: \\"RED\\" });
+|} = deepFreeze({ BLUE: \\"BLUE\\", GREEN: \\"GREEN\\", RED: \\"RED\\" });
 
 export type DateTime = string;
 
@@ -21,7 +23,7 @@ export type Dollars = number;
 
 export type EmptyEnum = empty;
 
-export const EmptyEnum$Values: {||} = Object.freeze({});
+export const EmptyEnum$Values: {||} = deepFreeze({});
 
 export type EmptyUnion = empty;
 
diff --git a/src/graphql/generateFlowTypes.js b/src/graphql/generateFlowTypes.js
index 9381599..5b71d76 100644
--- a/src/graphql/generateFlowTypes.js
+++ b/src/graphql/generateFlowTypes.js
@@ -77,7 +77,7 @@ export default function generateFlowTypes(
         const typeRhs = values.length === 0 ? "empty" : values.join(" | ");
         definitions.push(`export type ${typename} = ${typeRhs};`);
 
-        // export const E$Values: {|+A: "A", +B: "B"|} = Object.freeze(...);
+        // export const E$Values: {|+A: "A", +B: "B"|} = deepFreeze(...);
         const objectName = `${typename}$Values`;
         const objectType = [
           "{|",
@@ -85,7 +85,7 @@ export default function generateFlowTypes(
           "|}",
         ].join("");
         const objectValue = [
-          "Object.freeze({",
+          "deepFreeze({",
           values.map((x) => `${x}: ${x}`).join(", "),
           "})",
         ].join("");
@@ -127,6 +127,7 @@ export default function generateFlowTypes(
   const rawSource = [
     "// @flow",
     "// Autogenerated file. Do not edit.",
+    'import deepFreeze from "deep-freeze"',
     ...definitions,
   ].join("\n\n");
   return prettier.format(rawSource, prettierOptions);
diff --git a/src/graphql/mirror.js b/src/graphql/mirror.js
index a63e02c..ae68a74 100644
--- a/src/graphql/mirror.js
+++ b/src/graphql/mirror.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import type Database, {BindingDictionary, Statement} from "better-sqlite3";
 import stringify from "json-stable-stringify";
 
@@ -2038,7 +2039,7 @@ type UpdateResult = {
   +[string]: OwnDataUpdateResult | NodeConnectionsUpdateResult,
 };
 
-export const _FIELD_PREFIXES = Object.freeze({
+export const _FIELD_PREFIXES = deepFreeze({
   /**
    * A key of an `UpdateResult` has this prefix if and only if the
    * corresponding value represents `OwnDataUpdateResult`s.
diff --git a/src/plugins/defaultCredConfig.js b/src/plugins/defaultCredConfig.js
index ef0c044..ceb87b7 100644
--- a/src/plugins/defaultCredConfig.js
+++ b/src/plugins/defaultCredConfig.js
@@ -1,13 +1,14 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {userNodeType, repoNodeType, declaration} from "./github/declaration";
 import type {TimelineCredConfig} from "../analysis/timeline/timelineCred";
 
-export const DEFAULT_CRED_CONFIG: TimelineCredConfig = {
+export const DEFAULT_CRED_CONFIG: TimelineCredConfig = deepFreeze({
   scoreNodePrefix: userNodeType.prefix,
-  filterNodePrefixes: Object.freeze([userNodeType.prefix, repoNodeType.prefix]),
-  types: Object.freeze({
-    nodeTypes: Object.freeze(declaration.nodeTypes.slice()),
-    edgeTypes: Object.freeze(declaration.edgeTypes.slice()),
-  }),
-};
+  filterNodePrefixes: [userNodeType.prefix, repoNodeType.prefix],
+  types: {
+    nodeTypes: declaration.nodeTypes.slice(),
+    edgeTypes: declaration.edgeTypes.slice(),
+  },
+});
diff --git a/src/plugins/demo/declaration.js b/src/plugins/demo/declaration.js
index b441004..1c1abcc 100644
--- a/src/plugins/demo/declaration.js
+++ b/src/plugins/demo/declaration.js
@@ -1,12 +1,12 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
+
 import {NodeAddress, EdgeAddress} from "../../core/graph";
-
 import type {PluginDeclaration} from "../../analysis/pluginDeclaration";
-
 import type {EdgeType, NodeType} from "../../analysis/types";
 
-export const inserterNodeType: NodeType = Object.freeze({
+export const inserterNodeType: NodeType = deepFreeze({
   name: "inserter",
   pluralName: "inserters",
   prefix: NodeAddress.fromParts(["factorio", "inserter"]),
@@ -14,7 +14,7 @@ export const inserterNodeType: NodeType = Object.freeze({
   description: "Nodes for Factorio inserter objects in demo plugin",
 });
 
-export const machineNodeType: NodeType = Object.freeze({
+export const machineNodeType: NodeType = deepFreeze({
   name: "machine",
   pluralName: "machines",
   prefix: NodeAddress.fromParts(["factorio", "machine"]),
@@ -22,7 +22,7 @@ export const machineNodeType: NodeType = Object.freeze({
   description: "Nodes for Factorio machine objects in demo plugin",
 });
 
-export const assemblesEdgeType: EdgeType = Object.freeze({
+export const assemblesEdgeType: EdgeType = deepFreeze({
   forwardName: "assembles",
   backwardName: "is assembled by",
   defaultWeight: {forwards: 2, backwards: 2 ** -2},
@@ -30,7 +30,7 @@ export const assemblesEdgeType: EdgeType = Object.freeze({
   description: "Connects assembly machines to products they assemble.",
 });
 
-export const transportsEdgeType: EdgeType = Object.freeze({
+export const transportsEdgeType: EdgeType = deepFreeze({
   forwardName: "transports",
   backwardName: "is transported by",
   defaultWeight: {forwards: 2, backwards: 2 ** -1},
@@ -38,10 +38,10 @@ export const transportsEdgeType: EdgeType = Object.freeze({
   description: "Connects transporter belts to objects they transport.",
 });
 
-export const declaration: PluginDeclaration = Object.freeze({
+export const declaration: PluginDeclaration = deepFreeze({
   name: "Factorio demo adapter",
   nodePrefix: NodeAddress.fromParts(["factorio"]),
-  nodeTypes: Object.freeze([inserterNodeType, machineNodeType]),
+  nodeTypes: [inserterNodeType, machineNodeType],
   edgePrefix: EdgeAddress.fromParts(["factorio"]),
-  edgeTypes: Object.freeze([assemblesEdgeType, transportsEdgeType]),
+  edgeTypes: [assemblesEdgeType, transportsEdgeType],
 });
diff --git a/src/plugins/demo/graph.js b/src/plugins/demo/graph.js
index 75ed3de..fe8ce75 100644
--- a/src/plugins/demo/graph.js
+++ b/src/plugins/demo/graph.js
@@ -1,16 +1,17 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {Graph} from "../../core/graph";
 import {partsNode, partsEdge} from "../../core/graphTestUtil";
 
-export const nodes = Object.freeze({
+export const nodes = deepFreeze({
   inserter1: partsNode(["factorio", "inserter", "1"]),
   machine1: partsNode(["factorio", "machine", "1"]),
   inserter2: partsNode(["factorio", "inserter", "2"]),
   machine2: partsNode(["factorio", "machine", "2"]),
 });
 
-export const edges = Object.freeze({
+export const edges = deepFreeze({
   transports1: partsEdge(
     ["factorio", "transports", "1"],
     nodes.inserter1,
diff --git a/src/plugins/git/declaration.js b/src/plugins/git/declaration.js
index eb26d7a..a944e63 100644
--- a/src/plugins/git/declaration.js
+++ b/src/plugins/git/declaration.js
@@ -1,11 +1,12 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import type {PluginDeclaration} from "../../analysis/pluginDeclaration";
 import type {NodeType} from "../../analysis/types";
 import * as N from "./nodes";
 import * as E from "./edges";
 
-const commitNodeType: NodeType = Object.freeze({
+const commitNodeType: NodeType = deepFreeze({
   name: "Commit",
   pluralName: "Commits",
   prefix: N.Prefix.commit,
@@ -13,7 +14,7 @@ const commitNodeType: NodeType = Object.freeze({
   description: "NodeType representing a git commit",
 });
 
-const hasParentEdgeType = Object.freeze({
+const hasParentEdgeType = deepFreeze({
   forwardName: "has parent",
   backwardName: "is parent of",
   prefix: E.Prefix.hasParent,
@@ -21,10 +22,10 @@ const hasParentEdgeType = Object.freeze({
   description: "Connects a Git commit to its parent commit(s).",
 });
 
-const nodeTypes = Object.freeze([commitNodeType]);
-const edgeTypes = Object.freeze([hasParentEdgeType]);
+const nodeTypes = deepFreeze([commitNodeType]);
+const edgeTypes = deepFreeze([hasParentEdgeType]);
 
-export const declaration: PluginDeclaration = Object.freeze({
+export const declaration: PluginDeclaration = deepFreeze({
   name: "Git",
   nodePrefix: N.Prefix.base,
   edgePrefix: E.Prefix.base,
diff --git a/src/plugins/git/edges.js b/src/plugins/git/edges.js
index 2581b00..fd2a5ab 100644
--- a/src/plugins/git/edges.js
+++ b/src/plugins/git/edges.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {
   type Edge,
   type EdgeAddressT,
@@ -21,7 +22,7 @@ function gitEdgeAddress(...parts: string[]): RawAddress {
   return EdgeAddress.append(GIT_PREFIX, ...parts);
 }
 
-export const Prefix = Object.freeze({
+export const Prefix = deepFreeze({
   base: GIT_PREFIX,
   hasParent: gitEdgeAddress(HAS_PARENT_TYPE),
 });
@@ -34,7 +35,7 @@ export type HasParentAddress = {|
 
 export type StructuredAddress = HasParentAddress;
 
-export const createEdge = Object.freeze({
+export const createEdge = deepFreeze({
   hasParent: (
     child: GitNode.CommitAddress,
     parent: GitNode.CommitAddress,
diff --git a/src/plugins/git/mergeRepository.test.js b/src/plugins/git/mergeRepository.test.js
index d5f5bdf..4bb85c7 100644
--- a/src/plugins/git/mergeRepository.test.js
+++ b/src/plugins/git/mergeRepository.test.js
@@ -1,15 +1,16 @@
 //@flow
 
+import deepFreeze from "deep-freeze";
 import {makeRepoId, repoIdToString, type RepoIdString} from "../../core/repoId";
 import type {Repository} from "./types";
 import {mergeRepository} from "./mergeRepository";
 
 describe("plugins/git/mergeRepository", () => {
   describe("mergeRepository", () => {
-    const empty: Repository = Object.freeze({commits: {}, commitToRepoId: {}});
+    const empty: Repository = deepFreeze({commits: {}, commitToRepoId: {}});
     const repoId1 = repoIdToString(makeRepoId("repo", "1"));
     const repoId2 = repoIdToString(makeRepoId("repo", "2"));
-    const repository1: Repository = Object.freeze({
+    const repository1: Repository = deepFreeze({
       commits: {
         commit1: {
           hash: "commit1",
@@ -31,7 +32,7 @@ describe("plugins/git/mergeRepository", () => {
         commit2: {[((repoId1: RepoIdString): any)]: true},
       },
     });
-    const repository2: Repository = Object.freeze({
+    const repository2: Repository = deepFreeze({
       commits: {
         commit1: {
           hash: "commit1",
@@ -89,7 +90,7 @@ describe("plugins/git/mergeRepository", () => {
       expect(mergeRepository([repository1, repository1])).toEqual(repository1);
     });
     it("throws an error if merging a repository with conflicting commits", () => {
-      const conflictingRepository: Repository = Object.freeze({
+      const conflictingRepository: Repository = deepFreeze({
         commits: {
           commit1: {
             hash: "commit1",
diff --git a/src/plugins/git/nodes.js b/src/plugins/git/nodes.js
index 374dab1..8ebc6f2 100644
--- a/src/plugins/git/nodes.js
+++ b/src/plugins/git/nodes.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {NodeAddress, type NodeAddressT} from "../../core/graph";
 import type {Hash} from "./types";
 
@@ -12,7 +13,7 @@ export function _gitAddress(...parts: string[]): RawAddress {
 
 export const COMMIT_TYPE: "COMMIT" = "COMMIT";
 
-export const Prefix = Object.freeze({
+export const Prefix = deepFreeze({
   base: GIT_PREFIX,
   commit: _gitAddress(COMMIT_TYPE),
 });
diff --git a/src/plugins/git/render.test.js b/src/plugins/git/render.test.js
index b5abe67..d98f220 100644
--- a/src/plugins/git/render.test.js
+++ b/src/plugins/git/render.test.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import * as N from "./nodes";
 import {shallow} from "enzyme";
 import {description} from "./render";
@@ -48,7 +49,7 @@ describe("plugins/git/render", () => {
     createdAt: 123456789,
     parentHashes: [],
   };
-  const exampleRepository: Repository = Object.freeze({
+  const exampleRepository: Repository = deepFreeze({
     commits: {
       zeroRepoCommit,
       singleRepoCommit,
@@ -65,7 +66,7 @@ describe("plugins/git/render", () => {
     },
   });
 
-  const exampleGitGateway: GitGateway = Object.freeze({
+  const exampleGitGateway: GitGateway = deepFreeze({
     commitUrl(repo: RepoId, hash: Hash): URL {
       return repoIdToString(repo) + "/" + hash;
     },
diff --git a/src/plugins/github/blacklistedObjectIds.js b/src/plugins/github/blacklistedObjectIds.js
index 48a88cf..72c0350 100644
--- a/src/plugins/github/blacklistedObjectIds.js
+++ b/src/plugins/github/blacklistedObjectIds.js
@@ -1,8 +1,9 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import type {ObjectId} from "../../graphql/schema";
 
-export const BLACKLISTED_IDS: $ReadOnlyArray<ObjectId> = Object.freeze([
+export const BLACKLISTED_IDS: $ReadOnlyArray<ObjectId> = deepFreeze([
   // These are `Organization` nodes that are sometimes referenced in a
   // `User` context: in particular, as the author of a reaction.
   // See: https://gist.github.com/wchargin/a2b8561b81bcc932c84e493d2485ea8a
diff --git a/src/plugins/github/declaration.js b/src/plugins/github/declaration.js
index 801a9ed..1642e4c 100644
--- a/src/plugins/github/declaration.js
+++ b/src/plugins/github/declaration.js
@@ -1,11 +1,12 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import type {PluginDeclaration} from "../../analysis/pluginDeclaration";
 import * as N from "./nodes";
 import * as E from "./edges";
 import dedent from "../../util/dedent";
 
-export const repoNodeType = Object.freeze({
+export const repoNodeType = deepFreeze({
   name: "Repository",
   pluralName: "Repositories",
   prefix: N.Prefix.repo,
@@ -13,7 +14,7 @@ export const repoNodeType = Object.freeze({
   description: "NodeType for a GitHub repository",
 });
 
-const issueNodeType = Object.freeze({
+const issueNodeType = deepFreeze({
   name: "Issue",
   pluralName: "Issues",
   prefix: N.Prefix.issue,
@@ -21,7 +22,7 @@ const issueNodeType = Object.freeze({
   description: "NodeType for a GitHub issue",
 });
 
-const pullNodeType = Object.freeze({
+const pullNodeType = deepFreeze({
   name: "Pull request",
   pluralName: "Pull requests",
   prefix: N.Prefix.pull,
@@ -29,7 +30,7 @@ const pullNodeType = Object.freeze({
   description: "NodeType for a GitHub pull request",
 });
 
-const reviewNodeType = Object.freeze({
+const reviewNodeType = deepFreeze({
   name: "Pull request review",
   pluralName: "Pull request reviews",
   prefix: N.Prefix.review,
@@ -37,7 +38,7 @@ const reviewNodeType = Object.freeze({
   description: "NodeType for a GitHub code review",
 });
 
-const commentNodeType = Object.freeze({
+const commentNodeType = deepFreeze({
   name: "Comment",
   pluralName: "Comments",
   prefix: N.Prefix.comment,
@@ -45,7 +46,7 @@ const commentNodeType = Object.freeze({
   description: "NodeType for a GitHub comment",
 });
 
-const commitNodeType = Object.freeze({
+const commitNodeType = deepFreeze({
   name: "Commit",
   pluralName: "Commits",
   prefix: N.Prefix.commit,
@@ -54,7 +55,7 @@ const commitNodeType = Object.freeze({
     "Represents a particular Git commit on GitHub, i.e. scoped to a particular repository",
 });
 
-export const userNodeType = Object.freeze({
+export const userNodeType = deepFreeze({
   name: "User",
   pluralName: "Users",
   prefix: N.Prefix.user,
@@ -62,7 +63,7 @@ export const userNodeType = Object.freeze({
   description: "NodeType for a GitHub user",
 });
 
-const botNodeType = Object.freeze({
+const botNodeType = deepFreeze({
   name: "Bot",
   pluralName: "Bots",
   prefix: N.Prefix.bot,
@@ -70,7 +71,7 @@ const botNodeType = Object.freeze({
   description: "NodeType for a GitHub bot account",
 });
 
-const nodeTypes = Object.freeze([
+const nodeTypes = deepFreeze([
   repoNodeType,
   issueNodeType,
   pullNodeType,
@@ -81,7 +82,7 @@ const nodeTypes = Object.freeze([
   botNodeType,
 ]);
 
-const authorsEdgeType = Object.freeze({
+const authorsEdgeType = deepFreeze({
   forwardName: "authors",
   backwardName: "is authored by",
   defaultWeight: {forwards: 1 / 2, backwards: 1},
@@ -93,7 +94,7 @@ const authorsEdgeType = Object.freeze({
   `,
 });
 
-const hasParentEdgeType = Object.freeze({
+const hasParentEdgeType = deepFreeze({
   forwardName: "has parent",
   backwardName: "has child",
   defaultWeight: {forwards: 1, backwards: 1 / 4},
@@ -106,7 +107,7 @@ const hasParentEdgeType = Object.freeze({
   `,
 });
 
-const mergedAsEdgeType = Object.freeze({
+const mergedAsEdgeType = deepFreeze({
   forwardName: "merges",
   backwardName: "is merged by",
   defaultWeight: {forwards: 1 / 2, backwards: 1},
@@ -116,7 +117,7 @@ const mergedAsEdgeType = Object.freeze({
   `,
 });
 
-const referencesEdgeType = Object.freeze({
+const referencesEdgeType = deepFreeze({
   forwardName: "references",
   backwardName: "is referenced by",
   defaultWeight: {forwards: 1, backwards: 0},
@@ -130,7 +131,7 @@ const referencesEdgeType = Object.freeze({
   `,
 });
 
-const reactsHeartEdgeType = Object.freeze({
+const reactsHeartEdgeType = deepFreeze({
   forwardName: "reacted ❤️ to",
   backwardName: "got ❤️ from",
   defaultWeight: {forwards: 2, backwards: 0},
@@ -140,7 +141,7 @@ const reactsHeartEdgeType = Object.freeze({
   `,
 });
 
-const reactsThumbsUpEdgeType = Object.freeze({
+const reactsThumbsUpEdgeType = deepFreeze({
   forwardName: "reacted 👍 to",
   backwardName: "got 👍 from",
   defaultWeight: {forwards: 1, backwards: 0},
@@ -150,7 +151,7 @@ const reactsThumbsUpEdgeType = Object.freeze({
   `,
 });
 
-const reactsHoorayEdgeType = Object.freeze({
+const reactsHoorayEdgeType = deepFreeze({
   forwardName: "reacted 🎉 to",
   backwardName: "got 🎉 from",
   defaultWeight: {forwards: 4, backwards: 0},
@@ -160,7 +161,7 @@ const reactsHoorayEdgeType = Object.freeze({
   `,
 });
 
-const reactsRocketEdgeType = Object.freeze({
+const reactsRocketEdgeType = deepFreeze({
   forwardName: "reacted 🚀 to",
   backwardName: "got 🚀 from",
   defaultWeight: {forwards: 1, backwards: 0},
@@ -170,7 +171,7 @@ const reactsRocketEdgeType = Object.freeze({
   `,
 });
 
-const correspondsToCommitEdgeType = Object.freeze({
+const correspondsToCommitEdgeType = deepFreeze({
   forwardName: "corresponds to Git commit",
   backwardName: "merged on GitHub as",
   defaultWeight: {forwards: 1, backwards: 1},
@@ -180,7 +181,7 @@ const correspondsToCommitEdgeType = Object.freeze({
   `,
 });
 
-const edgeTypes = Object.freeze([
+const edgeTypes = deepFreeze([
   authorsEdgeType,
   hasParentEdgeType,
   mergedAsEdgeType,
@@ -192,7 +193,7 @@ const edgeTypes = Object.freeze([
   correspondsToCommitEdgeType,
 ]);
 
-export const declaration: PluginDeclaration = Object.freeze({
+export const declaration: PluginDeclaration = deepFreeze({
   name: "GitHub",
   nodePrefix: N.Prefix.base,
   edgePrefix: E.Prefix.base,
diff --git a/src/plugins/github/edges.js b/src/plugins/github/edges.js
index 0a7cfbe..6d47b4c 100644
--- a/src/plugins/github/edges.js
+++ b/src/plugins/github/edges.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {
   type Edge,
   type EdgeAddressT,
@@ -31,7 +32,7 @@ function githubEdgeAddress(...parts: string[]): RawAddress {
   return EdgeAddress.append(GITHUB_PREFIX, ...parts);
 }
 
-export const Prefix = Object.freeze({
+export const Prefix = deepFreeze({
   base: GITHUB_PREFIX,
   authors: githubEdgeAddress(AUTHORS_TYPE),
   mergedAs: githubEdgeAddress(MERGED_AS_TYPE),
@@ -82,7 +83,7 @@ export type StructuredAddress =
   | ReactsAddress
   | CorrespondsToCommitAddress;
 
-export const createEdge = Object.freeze({
+export const createEdge = deepFreeze({
   authors: (
     author: GithubNode.UserlikeAddress,
     content: GithubNode.AuthorableAddress,
diff --git a/src/plugins/github/graphqlTypes.js b/src/plugins/github/graphqlTypes.js
index b354333..ea3f3f4 100644
--- a/src/plugins/github/graphqlTypes.js
+++ b/src/plugins/github/graphqlTypes.js
@@ -2,6 +2,8 @@
 
 // Autogenerated file. Do not edit.
 
+import deepFreeze from "deep-freeze";
+
 export type Actor = Bot | Organization | User;
 
 export type Blob = {|
@@ -122,7 +124,7 @@ export const PullRequestReviewState$Values: {|
   +COMMENTED: "COMMENTED",
   +DISMISSED: "DISMISSED",
   +PENDING: "PENDING",
-|} = Object.freeze({
+|} = deepFreeze({
   APPROVED: "APPROVED",
   CHANGES_REQUESTED: "CHANGES_REQUESTED",
   COMMENTED: "COMMENTED",
@@ -157,7 +159,7 @@ export const ReactionContent$Values: {|
   +ROCKET: "ROCKET",
   +THUMBS_DOWN: "THUMBS_DOWN",
   +THUMBS_UP: "THUMBS_UP",
-|} = Object.freeze({
+|} = deepFreeze({
   CONFUSED: "CONFUSED",
   EYES: "EYES",
   HEART: "HEART",
diff --git a/src/plugins/github/nodes.js b/src/plugins/github/nodes.js
index 4b77170..fdf9a49 100644
--- a/src/plugins/github/nodes.js
+++ b/src/plugins/github/nodes.js
@@ -1,5 +1,6 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 import {NodeAddress, type NodeAddressT} from "../../core/graph";
 
 export opaque type RawAddress: NodeAddressT = NodeAddressT;
@@ -19,7 +20,7 @@ export const USERLIKE_TYPE: "USERLIKE" = "USERLIKE";
 export const USER_SUBTYPE: "USER" = "USER";
 export const BOT_SUBTYPE: "BOT" = "BOT";
 
-export const Prefix = Object.freeze({
+export const Prefix = deepFreeze({
   base: GITHUB_PREFIX,
   repo: _githubAddress(REPO_TYPE),
   issue: _githubAddress(ISSUE_TYPE),
diff --git a/src/webutil/Colors.js b/src/webutil/Colors.js
index deb3931..abde054 100644
--- a/src/webutil/Colors.js
+++ b/src/webutil/Colors.js
@@ -1,15 +1,16 @@
 // @flow
 
+import deepFreeze from "deep-freeze";
 export type HexColor = string;
 
-export default (Object.freeze({
-  brand: Object.freeze({
+export default (deepFreeze({
+  brand: {
     medium: "#0872A2",
     dark: "#3A066A",
-  }),
-  accent: Object.freeze({
+  },
+  accent: {
     medium: "#FF3201",
-  }),
+  },
 }): {|
   +brand: {|
     +medium: HexColor,
diff --git a/yarn.lock b/yarn.lock
index 27a0194..85c518c 100644
--- a/yarn.lock
+++ b/yarn.lock
@@ -2703,6 +2703,11 @@ deep-extend@^0.6.0:
   resolved "https://registry.yarnpkg.com/deep-extend/-/deep-extend-0.6.0.tgz#c4fa7c95404a17a9c3e8ca7e1537312b736330ac"
   integrity sha512-LOHxIOaPYdHlJRtCQfDIVZtfw/ufM8+rVj649RIHzcm/vGwQRXFt6OPqIFWsm2XEMrNIEtWR64sY1LEKD2vAOA==
 
+deep-freeze@^0.0.1:
+  version "0.0.1"
+  resolved "https://registry.yarnpkg.com/deep-freeze/-/deep-freeze-0.0.1.tgz#3a0b0005de18672819dfd38cd31f91179c893e84"
+  integrity sha1-OgsABd4YZygZ39OM0x+RF5yJPoQ=
+
 deep-is@~0.1.3:
   version "0.1.3"
   resolved "https://registry.yarnpkg.com/deep-is/-/deep-is-0.1.3.tgz#b369d6fb5dbc13eecf524f91b070feedc357cf34"