From f9124c318724fa09bbd2e8b739877c8870ac6115 Mon Sep 17 00:00:00 2001
From: Karl Floersch <karl@karlfloersch.com>
Date: Sat, 20 Jul 2019 11:11:42 -0400
Subject: [PATCH] Fix double prefix bug & small edits

---
 packages/core/src/app/db/iterator.ts           |  2 +-
 packages/core/src/app/db/range-bucket.ts       | 16 +++++++++-------
 packages/core/test/app/db/range-bucket.spec.ts | 12 ++++++------
 3 files changed, 16 insertions(+), 14 deletions(-)

diff --git a/packages/core/src/app/db/iterator.ts b/packages/core/src/app/db/iterator.ts
index 05a705b8..f58fd2a8 100644
--- a/packages/core/src/app/db/iterator.ts
+++ b/packages/core/src/app/db/iterator.ts
@@ -249,7 +249,7 @@ export class BaseRangeIterator extends BaseIterator {
    * @returns the RangeEntry at the next key.
    */
   public async nextRange(): Promise<RangeEntry> {
-    const res = await this.next()
+    const res: KV = await this.next()
     if (typeof res.key === 'undefined') {
       return
     }
diff --git a/packages/core/src/app/db/range-bucket.ts b/packages/core/src/app/db/range-bucket.ts
index 005e73a6..ee9aa7a0 100644
--- a/packages/core/src/app/db/range-bucket.ts
+++ b/packages/core/src/app/db/range-bucket.ts
@@ -47,12 +47,14 @@ export class BaseRangeBucket implements RangeBucket {
   ) {}
 
   /**
-   * Adds this RangeBucket's prefix to the target Buffer
-   * @param target A Buffer which will have the prefix prepended to it.
-   * @returns resulting Buffer `prefix+target`.
+   * Concatenates some value to this bucket's prefix.
+   * @param value Value to concatenate.
+   * @returns the value concatenated to the prefix.
    */
-  private addPrefix(target: Buffer): Buffer {
-    return Buffer.concat([this.prefix, target])
+  private addPrefix(value: Buffer): Buffer {
+    return value !== undefined
+      ? Buffer.concat([this.prefix, value])
+      : this.prefix
   }
 
   /**
@@ -289,12 +291,12 @@ export class BaseRangeBucket implements RangeBucket {
    * @param options Parameters for the iterator.
    * @returns the iterator instance.
    */
-  public iterator(options?: IteratorOptions): RangeIterator {
+  public iterator(options: IteratorOptions = {}): RangeIterator {
     const rangeIterator = new BaseRangeIterator(
       this.db,
       {
         ...options,
-        prefix: this.addPrefix(this.prefix),
+        prefix: this.addPrefix(options.prefix),
       },
       (res: KV) => this.resultToRange(res)
     )
diff --git a/packages/core/test/app/db/range-bucket.spec.ts b/packages/core/test/app/db/range-bucket.spec.ts
index afb5f01c..969e5e2e 100644
--- a/packages/core/test/app/db/range-bucket.spec.ts
+++ b/packages/core/test/app/db/range-bucket.spec.ts
@@ -274,14 +274,14 @@ describe('RangeDB', () => {
     it('allows nextRange() to be called by the iterator returning a RangeEntry instead of a KV', async () => {
       const testRanges = {
         inputs: [
-          { start: '0', end: '100', value: 'x4' },
-          { start: '100', end: '200', value: 'y4' },
-          { start: '50', end: '150', value: 'z4' },
+          { start: '0', end: '100', value: 'x' },
+          { start: '100', end: '200', value: 'y' },
+          { start: '200', end: '225', value: 'z' },
         ],
         expectedResults: [
-          { start: '0', end: '50', value: 'x4' },
-          { start: '50', end: '150', value: 'z4' },
-          { start: '150', end: '200', value: 'y4' },
+          { start: '0', end: '100', value: 'x' },
+          { start: '100', end: '200', value: 'y' },
+          { start: '200', end: '225', value: 'z' },
         ],
       }