fix(SwingSet): enable getKeys('','') in blockBuffer/crankBuffer

Previously, these two wrappers didn't provide the same functionality as their
underlying HostStorage: you couldn't use empty strings for the start/end to
get more keys.

Also, add type assertions to crankBuffer to detect non-string keys/values
earlier than commitCrank.

packages/SwingSet/src/blockBuffer.js

@@ -43,7 +43,7 @@ export function buildBlockBuffer(hostDB) {
         keys.delete(k);
       }
       for (const k of Array.from(keys).sort()) {
-        if (start <= k && k < end) {
+        if ((start === '' || start <= k) && (end === '' || k < end)) {
           yield k;
         }
       }

packages/SwingSet/src/kernel/state/storageWrapper.js

@@ -121,6 +121,8 @@ export function buildCrankBuffer(kvStore) {
     },
 
     *getKeys(start, end) {
+      assert.typeof(start, 'string');
+      assert.typeof(end, 'string');
       const keys = new Set(kvStore.getKeys(start, end));
       for (const k of additions.keys()) {
         keys.add(k);
@@ -129,13 +131,14 @@ export function buildCrankBuffer(kvStore) {
         keys.delete(k);
       }
       for (const k of Array.from(keys).sort()) {
-        if (start <= k && k < end) {
+        if ((start === '' || start <= k) && (end === '' || k < end)) {
           yield k;
         }
       }
     },
 
     get(key) {
+      assert.typeof(key, 'string');
       if (additions.has(key)) {
         return additions.get(key);
       }
@@ -146,11 +149,14 @@ export function buildCrankBuffer(kvStore) {
     },
 
     set(key, value) {
+      assert.typeof(key, 'string');
+      assert.typeof(value, 'string');
       additions.set(key, value);
       deletions.delete(key);
     },
 
     delete(key) {
+      assert.typeof(key, 'string');
       additions.delete(key);
       deletions.add(key);
     },

packages/SwingSet/test/test-state.js

@@ -47,6 +47,9 @@ function testStorage(t, s, getState, commit) {
   s.set('foo3', 'f3');
   t.deepEqual(Array.from(s.getKeys('foo1', 'foo3')), ['foo1', 'foo2']);
   t.deepEqual(Array.from(s.getKeys('foo1', 'foo4')), ['foo1', 'foo2', 'foo3']);
+  t.deepEqual(Array.from(s.getKeys('', '')), ['foo', 'foo1', 'foo2', 'foo3']);
+  t.deepEqual(Array.from(s.getKeys('foo1', '')), ['foo1', 'foo2', 'foo3']);
+  t.deepEqual(Array.from(s.getKeys('', 'foo2')), ['foo', 'foo1']);
 
   s.delete('foo2');
   t.falsy(s.has('foo2'));
@@ -250,21 +253,15 @@ function duplicateKeeper(getState) {
 }
 
 test('hostStorage param guards', async t => {
-  const { kstorage, commitCrank } = buildKeeperStorageInMemory();
-  kstorage.set('foo', true);
-  t.throws(commitCrank, { message: /must be a string/ });
-  kstorage.set(true, 'foo');
-  t.throws(commitCrank, { message: /must be a string/ });
-  kstorage.has(true);
-  t.throws(commitCrank, { message: /must be a string/ });
-  kstorage.getKeys('foo', true);
-  t.throws(commitCrank, { message: /must be a string/ });
-  kstorage.getKeys(true, 'foo');
-  t.throws(commitCrank, { message: /must be a string/ });
-  kstorage.get(true);
-  t.throws(commitCrank, { message: /must be a string/ });
-  kstorage.delete(true);
-  t.throws(commitCrank, { message: /must be a string/ });
+  const { kstorage } = buildKeeperStorageInMemory();
+  const exp = { message: /true must be a string/ };
+  t.throws(() => kstorage.set('foo', true), exp);
+  t.throws(() => kstorage.set(true, 'foo'), exp);
+  t.throws(() => kstorage.has(true), exp);
+  t.throws(() => Array.from(kstorage.getKeys('foo', true)), exp);
+  t.throws(() => Array.from(kstorage.getKeys(true, 'foo')), exp);
+  t.throws(() => kstorage.get(true), exp);
+  t.throws(() => kstorage.delete(true), exp);
 });
 
 test('kernel state', async t => {