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diff --git a/test/gtest/scc.cpp b/test/gtest/scc.cpp
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+++ b/test/gtest/scc.cpp
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+/*
+ * Copyright 2024 WebAssembly Community Group participants
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <vector>
+
+#include "support/strongly_connected_components.h"
+#include "gtest/gtest.h"
+
+using namespace wasm;
+
+struct IntIt {
+  using value_type = unsigned;
+  using difference_type = std::ptrdiff_t;
+  using reference = unsigned&;
+  using pointer = unsigned*;
+  using iterator_category = std::input_iterator_tag;
+
+  unsigned i = 0;
+
+  bool operator==(const IntIt& other) const { return i == other.i; }
+  bool operator!=(const IntIt& other) const { return !(*this == other); }
+  unsigned operator*() { return i; }
+  IntIt& operator++() {
+    ++i;
+    return *this;
+  }
+  IntIt operator++(int) {
+    IntIt it = *this;
+    ++(*this);
+    return it;
+  }
+};
+
+struct Graph {
+  std::vector<std::set<unsigned>> graph;
+
+  explicit Graph(unsigned size) : graph(size) {}
+
+  void addEdge(unsigned from, unsigned to) {
+    assert(from < graph.size());
+    assert(to < graph.size());
+    graph[from].insert(to);
+  }
+
+  const std::set<unsigned>& children(unsigned parent) const {
+    return graph[parent];
+  }
+
+  IntIt begin() const { return {}; }
+  IntIt end() const { return {unsigned(graph.size())}; }
+};
+
+struct GraphSCCs : SCCs<IntIt, GraphSCCs> {
+  const Graph& graph;
+  GraphSCCs(const Graph& graph)
+    : SCCs<IntIt, GraphSCCs>(graph.begin(), graph.end()), graph(graph) {}
+
+  void pushChildren(unsigned parent) {
+    for (auto child : graph.children(parent)) {
+      push(child);
+    }
+  }
+};
+
+using SCCSet = std::set<std::set<unsigned>>;
+
+SCCSet getSCCs(const Graph& graph) {
+  SCCSet set;
+  for (auto scc : GraphSCCs(graph)) {
+    set.emplace(scc.begin(), scc.end());
+  }
+  return set;
+}
+
+TEST(SCCTest, Empty) {
+  Graph graph(0);
+  GraphSCCs sccs(graph);
+  auto it = sccs.begin();
+  EXPECT_EQ(it, sccs.end());
+
+  EXPECT_EQ(getSCCs(graph), SCCSet{});
+}
+
+TEST(SCCTest, Singleton) {
+  Graph graph(1);
+  GraphSCCs sccs(graph);
+
+  auto it = sccs.begin();
+  ASSERT_NE(it, sccs.end());
+
+  auto scc = *it;
+  auto sccIt = scc.begin();
+  ASSERT_NE(sccIt, scc.end());
+  EXPECT_EQ(*sccIt, 0u);
+
+  ++sccIt;
+  EXPECT_EQ(sccIt, scc.end());
+  ASSERT_NE(it, sccs.end());
+
+  ++it;
+  EXPECT_EQ(it, sccs.end());
+
+  EXPECT_EQ(getSCCs(graph), SCCSet{{0}});
+}
+
+TEST(SCCTest, SingletonLoop) {
+  // Same as above, but now there is an edge. The results are the same.
+  Graph graph(1);
+  graph.addEdge(0, 0);
+  GraphSCCs sccs(graph);
+
+  auto it = sccs.begin();
+  ASSERT_NE(it, sccs.end());
+
+  auto scc = *it;
+  auto sccIt = scc.begin();
+  ASSERT_NE(sccIt, scc.end());
+  EXPECT_EQ(*sccIt, 0u);
+
+  ++sccIt;
+  EXPECT_EQ(sccIt, scc.end());
+  ASSERT_NE(it, sccs.end());
+
+  ++it;
+  EXPECT_EQ(it, sccs.end());
+
+  EXPECT_EQ(getSCCs(graph), SCCSet{{0}});
+}
+
+TEST(SCCTest, DerefPostIncrement) {
+  // Valid input iterators must have *it++ yield the value from before the
+  // increment.
+  Graph graph(1);
+  GraphSCCs sccs(graph);
+  auto it = sccs.begin()->begin();
+  EXPECT_EQ(*it++, 0u);
+}
+
+TEST(SCCTest, Disconnected) {
+  // There are no edges between the vertices.
+  Graph graph(3);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0}, {1}, {2}}));
+}
+
+TEST(SCCTest, Chain) {
+  // 0 -> 1 -> 2
+  Graph graph(3);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 2);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0}, {1}, {2}}));
+}
+
+TEST(SCCTest, ChainReverse) {
+  // 0 <- 1 <- 2
+  Graph graph(3);
+  graph.addEdge(2, 1);
+  graph.addEdge(1, 0);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0}, {1}, {2}}));
+}
+
+TEST(SCCTest, Loop) {
+  // 0 -> 1 -> 2 -> 0
+  // There is only one SCC here.
+  Graph graph(3);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 2);
+  graph.addEdge(2, 0);
+  EXPECT_EQ(getSCCs(graph), (SCCSet({{0, 1, 2}})));
+}
+
+TEST(SCCTest, LoopReverse) {
+  // 0 <- 1 <- 2 <- 0
+  // There is only one SCC here.
+  Graph graph(3);
+  graph.addEdge(0, 2);
+  graph.addEdge(2, 1);
+  graph.addEdge(1, 0);
+  EXPECT_EQ(getSCCs(graph), (SCCSet({{0, 1, 2}})));
+}
+
+TEST(SCCTest, Full) {
+  // Fully connected graph has one SCC.
+  Graph graph(3);
+  for (unsigned i = 0; i < 3; ++i) {
+    for (unsigned j = 0; j < 3; ++j) {
+      graph.addEdge(i, j);
+    }
+  }
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0, 1, 2}}));
+}
+
+TEST(SCCTest, TwoAndOne) {
+  // 0 <-> 1 -> 2
+  Graph graph(3);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 0);
+  graph.addEdge(1, 2);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0, 1}, {2}}));
+}
+
+TEST(SCCTest, TwoAndOneRedundant) {
+  // 2 <- 0 <-> 1 -> 2
+  Graph graph(3);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 0);
+  graph.addEdge(1, 2);
+  // New from previous, doesn't affect result.
+  graph.addEdge(0, 2);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0, 1}, {2}}));
+}
+
+TEST(SCCTest, OneAndTwo) {
+  // 0 -> 1 <-> 2
+  Graph graph(3);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 2);
+  graph.addEdge(2, 1);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0}, {1, 2}}));
+}
+
+TEST(SCCTest, TwoAndTwoDisconnected) {
+  // 0 <-> 1  2 <-> 3
+  Graph graph(4);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 0);
+  graph.addEdge(2, 3);
+  graph.addEdge(3, 2);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0, 1}, {2, 3}}));
+}
+
+TEST(SCCTest, TwoAndTwo) {
+  // 0 <-> 1 -> 2 <-> 3
+  Graph graph(4);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 0);
+  graph.addEdge(2, 3);
+  graph.addEdge(3, 2);
+  // New from previous, doesn't affect result
+  graph.addEdge(1, 2);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0, 1}, {2, 3}}));
+}
+
+TEST(SCCTest, DoublyLinkedList) {
+  // 0 <-> 1 <-> 2 <-> 3
+  Graph graph(4);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 0);
+  graph.addEdge(2, 3);
+  graph.addEdge(3, 2);
+  graph.addEdge(1, 2);
+  // New from previous, combines SCCs.
+  graph.addEdge(2, 1);
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0, 1, 2, 3}}));
+}
+
+TEST(SCCTest, BigTree) {
+  // 012 <- 345 -> 678
+  Graph graph(9);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 2);
+  graph.addEdge(2, 0);
+
+  graph.addEdge(3, 4);
+  graph.addEdge(4, 5);
+  graph.addEdge(5, 3);
+
+  graph.addEdge(6, 7);
+  graph.addEdge(7, 8);
+  graph.addEdge(8, 6);
+
+  graph.addEdge(3, 2);
+  graph.addEdge(5, 6);
+
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0, 1, 2}, {3, 4, 5}, {6, 7, 8}}));
+}
+
+TEST(SCCTest, BigDiamond) {
+  // 67 <- 01 <- 23 -> 45 -> 67
+  Graph graph(8);
+  graph.addEdge(0, 1);
+  graph.addEdge(1, 0);
+
+  graph.addEdge(2, 3);
+  graph.addEdge(3, 2);
+
+  graph.addEdge(4, 5);
+  graph.addEdge(5, 4);
+
+  graph.addEdge(6, 7);
+  graph.addEdge(7, 6);
+
+  graph.addEdge(2, 0);
+  graph.addEdge(2, 4);
+  graph.addEdge(0, 6);
+  graph.addEdge(4, 6);
+
+  EXPECT_EQ(getSCCs(graph), (SCCSet{{0, 1}, {2, 3}, {4, 5}, {6, 7}}));
+}