From ecd677e71461d8524127c83935a2a0d47c2c39f4 Mon Sep 17 00:00:00 2001
From: Ivan Tymoshenko <ivan@tymoshenko.me>
Date: Sat, 21 Oct 2023 13:18:20 +0200
Subject: [PATCH 1/3] fix: throw an error if target schema not found

---
 index.js                  |  4 ++++
 test/deref-schema.test.js | 39 +++++++++++++++++++++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/index.js b/index.js
index f5059c0..d1a082e 100644
--- a/index.js
+++ b/index.js
@@ -97,6 +97,10 @@ class RefResolver {
       } = this.#parseSchemaRef(ref.ref, ref.sourceSchemaId)
 
       const targetSchema = this.getDerefSchema(refSchemaId, refJsonPointer)
+      if (targetSchema === null) {
+        throw new Error(`Cannot resolve ref "${ref.ref}".`)
+      }
+
       ref.targetSchema = targetSchema
       ref.targetSchemaId = refSchemaId
     }
diff --git a/test/deref-schema.test.js b/test/deref-schema.test.js
index facfc58..d0b196b 100644
--- a/test/deref-schema.test.js
+++ b/test/deref-schema.test.js
@@ -192,3 +192,42 @@ test('should clone schema without refs', () => {
     }
   })
 })
+
+test('should throw if target ref schema is not found', () => {
+  const inputSchema = {
+    $id: 'http://example.com/root.json',
+    definitions: {
+      A: { $id: '#foo' },
+      B: {
+        $id: 'other.json',
+        definitions: {
+          X: { $id: '#bar', type: 'string' },
+          Y: { $id: 't/inner.json' }
+        }
+      },
+      C: {
+        $id: 'urn:uuid:ee564b8a-7a87-4125-8c96-e9f123d6766f',
+        type: 'object'
+      }
+    }
+  }
+
+  const addresSchema = {
+    $id: 'relativeAddress', // Note: prefer always absolute URI like: http://mysite.com
+    type: 'object',
+    properties: {
+      zip: { $ref: 'urn:uuid:ee564b8a-7a87-4125-8c96-e9f123d6766f' },
+      city2: { $ref: '#foo' }
+    }
+  }
+
+  const refResolver = new RefResolver()
+  refResolver.addSchema(inputSchema)
+  refResolver.addSchema(addresSchema)
+
+  try {
+    refResolver.derefSchema('relativeAddress')
+  } catch (error) {
+    assert.strictEqual(error.message, 'Cannot resolve ref "#foo".')
+  }
+})

From c5bd7a40060f9641a69b8955492390f4c951134d Mon Sep 17 00:00:00 2001
From: Ivan Tymoshenko <ivan@tymoshenko.me>
Date: Sat, 21 Oct 2023 13:40:44 +0200
Subject: [PATCH 2/3] update error message

---
 index.js                  | 4 +++-
 test/deref-schema.test.js | 5 ++++-
 2 files changed, 7 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index d1a082e..ea0b3a5 100644
--- a/index.js
+++ b/index.js
@@ -98,7 +98,9 @@ class RefResolver {
 
       const targetSchema = this.getDerefSchema(refSchemaId, refJsonPointer)
       if (targetSchema === null) {
-        throw new Error(`Cannot resolve ref "${ref.ref}".`)
+        throw new Error(
+          `Cannot resolve ref "${ref.ref}". Ref ${refJsonPointer} is not found in schema "${refSchemaId}".`
+        )
       }
 
       ref.targetSchema = targetSchema
diff --git a/test/deref-schema.test.js b/test/deref-schema.test.js
index d0b196b..8d35d7b 100644
--- a/test/deref-schema.test.js
+++ b/test/deref-schema.test.js
@@ -228,6 +228,9 @@ test('should throw if target ref schema is not found', () => {
   try {
     refResolver.derefSchema('relativeAddress')
   } catch (error) {
-    assert.strictEqual(error.message, 'Cannot resolve ref "#foo".')
+    assert.strictEqual(
+      error.message,
+      'Cannot resolve ref "#foo". Ref #foo is not found in schema "relativeAddress".'
+    )
   }
 })

From 5beb72c6bd81d967cb55b223fe5c9364612c1132 Mon Sep 17 00:00:00 2001
From: Ivan Tymoshenko <ivan@tymoshenko.me>
Date: Sat, 21 Oct 2023 13:42:12 +0200
Subject: [PATCH 3/3] update error message

---
 index.js                  | 2 +-
 test/deref-schema.test.js | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/index.js b/index.js
index ea0b3a5..a912273 100644
--- a/index.js
+++ b/index.js
@@ -99,7 +99,7 @@ class RefResolver {
       const targetSchema = this.getDerefSchema(refSchemaId, refJsonPointer)
       if (targetSchema === null) {
         throw new Error(
-          `Cannot resolve ref "${ref.ref}". Ref ${refJsonPointer} is not found in schema "${refSchemaId}".`
+          `Cannot resolve ref "${ref.ref}". Ref "${refJsonPointer}" is not found in schema "${refSchemaId}".`
         )
       }
 
diff --git a/test/deref-schema.test.js b/test/deref-schema.test.js
index 8d35d7b..2efd5d7 100644
--- a/test/deref-schema.test.js
+++ b/test/deref-schema.test.js
@@ -230,7 +230,7 @@ test('should throw if target ref schema is not found', () => {
   } catch (error) {
     assert.strictEqual(
       error.message,
-      'Cannot resolve ref "#foo". Ref #foo is not found in schema "relativeAddress".'
+      'Cannot resolve ref "#foo". Ref "#foo" is not found in schema "relativeAddress".'
     )
   }
 })