fixing flatMapList to not wreck the original values

magnusandy · Mar 16, 2019 · 942eaab · 942eaab
1 parent 51d32b0
commit 942eaab
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Showing 4 changed files with 2,123 additions and 12 deletions.
diff --git a/package.json b/package.json
@@ -36,7 +36,7 @@
     "coveralls": "^3.0.2",
     "istanbul": "^0.4.5",
     "lazy.js": "^0.5.1",
-    "lodash": "^4.17.10",
+    "lodash": "^4.17.11",
     "mocha": "^5.2.0",
     "mocha-lcov-reporter": "^1.3.0",
     "nyc": "^12.0.2",

diff --git a/processor.ts b/processor.ts
@@ -333,7 +333,7 @@ class ListFlatMapProcessor<Input, Output> extends PureStatelessProcessor<Input,
         } else if (this.inputs.length > 0) {
             const nextSource: Optional<Input> = this.takeNextInput();
             if (nextSource.isPresent()) {
-                this.outputList = this.Function(nextSource.get());
+                this.outputList = [...this.Function(nextSource.get())];
                 return this.processAndGetNext();
             }
         }

diff --git a/test/streamTest.ts b/test/streamTest.ts
@@ -426,6 +426,28 @@ describe('Stream tests', () => {
     });
 
     describe('flatMapList', () => {
+        it('should not consume the source list', () => {
+            const grid = [
+                [1,2,3],
+                [4,5,6],
+                [7,8,9]
+            ];
+
+            const expected = [
+                [1,2,3],
+                [4,5,6],
+                [7,8,9]
+            ];
+
+            Stream.of(grid)
+                .flatMapList(Function.identity())
+                .collect(Collectors.toList());
+
+            expect(grid[0]).to.have.members(expected[0]);
+            expect(grid[1]).to.have.members(expected[1])
+            expect(grid[2]).to.have.members(expected[2])
+        });
+
         it('it should, flatten a stream of lists', () => {
             const l1 = [1, 2, 3];
             const l2 = [1, 2, 3];