[llvm] Unittests and usability for BitstreamWriter incremental flushing (PR #92983)

[Mircea Trofin via llvm-commits]

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@@ -55,4 +61,77 @@ TEST(BitstreamWriterTest, emitBlob4ByteAligned) {
   EXPECT_EQ(StringRef("str0"), Buffer);
 }
 
+class BitstreamWriterFlushTest : public ::testing::TestWithParam<int> {
+protected:
+  const unsigned BlkID = bitc::FIRST_APPLICATION_BLOCKID + 17;
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mtrofin wrote:

ugh. random number. added comment.

https://github.com/llvm/llvm-project/pull/92983