[wasm] Fix decoder unit tests

There are wasm tests which are supposed to fail, but they fail for the
wrong reason (because blocks do not declare their type).
This CL fixes this, and changes the error output to contain the
expected and observed results for better debuggability.

R=titzer@chromium.org

Change-Id: Ibbd7883e43677a91f858575578586c9e9d1641d5
Reviewed-on: https://chromium-review.googlesource.com/571810Reviewed-by: Andreas Haas <ahaas@chromium.org>
Commit-Queue: Clemens Hammacher <clemensh@chromium.org>
Cr-Commit-Position: refs/heads/master@{#46698}

test/unittests/wasm/function-body-decoder-unittest.cc

@@ -125,17 +125,15 @@ class FunctionBodyDecoderTest : public TestWithZone {
         zone()->allocator(), module == nullptr ? nullptr : module->module, sig,
         start, end);
 
-    if (result.ok() != expected_success) {
-      uint32_t pc = result.error_offset();
-      std::ostringstream str;
-      if (expected_success) {
-        str << "Verification failed: pc = +" << pc
-            << ", msg = " << result.error_msg();
-      } else {
-        str << "Verification successed, expected failure; pc = +" << pc;
-      }
-      EXPECT_TRUE(false) << str.str();
+    uint32_t pc = result.error_offset();
+    std::ostringstream str;
+    if (expected_success) {
+      str << "Verification failed: pc = +" << pc
+          << ", msg = " << result.error_msg();
+    } else {
+      str << "Verification successed, expected failure; pc = +" << pc;
     }
+    EXPECT_EQ(result.ok(), expected_success) << str.str();
   }
 
   void TestBinop(WasmOpcode opcode, FunctionSig* success) {
@@ -421,20 +419,20 @@ TEST_F(FunctionBodyDecoderTest, Binops_off_end) {
 }
 
 TEST_F(FunctionBodyDecoderTest, BinopsAcrossBlock1) {
-  static const byte code[] = {WASM_ZERO, kExprBlock, WASM_ZERO, kExprI32Add,
-                              kExprEnd};
+  static const byte code[] = {WASM_ZERO, kExprBlock,  kLocalI32,
+                              WASM_ZERO, kExprI32Add, kExprEnd};
   EXPECT_FAILURE_C(i_i, code);
 }
 
 TEST_F(FunctionBodyDecoderTest, BinopsAcrossBlock2) {
-  static const byte code[] = {WASM_ZERO, WASM_ZERO, kExprBlock, kExprI32Add,
-                              kExprEnd};
+  static const byte code[] = {WASM_ZERO, WASM_ZERO,   kExprBlock,
+                              kLocalI32, kExprI32Add, kExprEnd};
   EXPECT_FAILURE_C(i_i, code);
 }
 
 TEST_F(FunctionBodyDecoderTest, BinopsAcrossBlock3) {
-  static const byte code[] = {WASM_ZERO, WASM_ZERO,   kExprIf, kExprI32Add,
-                              kExprElse, kExprI32Add, kExprEnd};
+  static const byte code[] = {WASM_ZERO,   WASM_ZERO, kExprIf,     kLocalI32,
+                              kExprI32Add, kExprElse, kExprI32Add, kExprEnd};
   EXPECT_FAILURE_C(i_i, code);
 }