Improve logging and debugging

- Add unit tests for BasicBlock building logic

ep20/src/test/java/org/teachfx/antlr4/ep20/pass/cfg/BasicBlockTest.java

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+package org.teachfx.antlr4.ep20.pass.cfg;
+
+import org.junit.jupiter.api.Test;
+import org.teachfx.antlr4.ep20.ir.IRNode;
+import org.teachfx.antlr4.ep20.ir.expr.ImmValue;
+import org.teachfx.antlr4.ep20.ir.expr.VarSlot;
+import org.teachfx.antlr4.ep20.ir.expr.addr.FrameSlot;
+import org.teachfx.antlr4.ep20.ir.expr.arith.BinExpr;
+import org.teachfx.antlr4.ep20.ir.expr.val.ConstVal;
+import org.teachfx.antlr4.ep20.ir.stmt.CJMP;
+import org.teachfx.antlr4.ep20.ir.stmt.FuncEntryLabel;
+import org.teachfx.antlr4.ep20.ir.stmt.JMP;
+import org.teachfx.antlr4.ep20.ir.stmt.Label;
+import org.teachfx.antlr4.ep20.symtab.type.OperatorType;
+import org.teachfx.antlr4.ep20.utils.Kind;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class BasicBlockTest {
+
+    @Test
+    void testBuildFromLinearBlockWhenNoInstructionsThenEmptyBlock() {
+        // Arrange
+        LinearIRBlock block = new LinearIRBlock();
+        List<BasicBlock<IRNode>> cachedNodes = new ArrayList<>();
+
+        // Act
+        BasicBlock<IRNode> basicBlock = BasicBlock.buildFromLinearBlock(block, cachedNodes);
+
+        // Assert
+        assertTrue(basicBlock.isEmpty(), "BasicBlock should be empty when created from an empty LinearIRBlock");
+    }
+
+    @Test
+    void testBuildFromLinearBlockWhenOneInstructionThenOneInstructionBlock() {
+        // Arrange
+        LinearIRBlock block = new LinearIRBlock();
+        block.addStmt(new Label("L1", null));
+        List<BasicBlock<IRNode>> cachedNodes = new ArrayList<>();
+
+        // Act
+        BasicBlock<IRNode> basicBlock = BasicBlock.buildFromLinearBlock(block, cachedNodes);
+
+        // Assert
+        assertEquals(1, basicBlock.codes.size(), "BasicBlock should have one instruction when created from a LinearIRBlock with one instruction");
+    }
+
+    @Test
+    void testBuildFromLinearBlockWhenMultipleInstructionsThenSameNumberOfInstructionsBlock() {
+        // Arrange
+        LinearIRBlock block = new LinearIRBlock();
+        LinearIRBlock thenBlock = new LinearIRBlock();
+        block.addStmt(new Label("L1", null));
+        block.addStmt(new JMP(thenBlock));
+        List<BasicBlock<IRNode>> cachedNodes = new ArrayList<>();
+
+        // Act
+        BasicBlock<IRNode> basicBlock = BasicBlock.buildFromLinearBlock(block, cachedNodes);
+
+        // Assert
+        assertEquals(2, basicBlock.codes.size(), "BasicBlock should have the same number of instructions as the LinearIRBlock");
+    }
+
+    @Test
+    void testBuildFromLinearBlockWhenJumpInstructionThenJumpInstructionBlock() {
+        // Arrange
+        LinearIRBlock block = new LinearIRBlock();
+        LinearIRBlock thenBlock = new LinearIRBlock();
+
+        JMP jumpInstruction = new JMP(thenBlock);
+        block.addStmt(jumpInstruction);
+        List<BasicBlock<IRNode>> cachedNodes = new ArrayList<>();
+
+        // Act
+        BasicBlock<IRNode> basicBlock = BasicBlock.buildFromLinearBlock(block, cachedNodes);
+
+        // Assert
+        assertTrue(basicBlock.getLastInstr() instanceof JMP, "BasicBlock should have a jump instruction when created from a LinearIRBlock with a jump instruction");
+    }
+
+    @Test
+    void testBuildFromLinearBlockWhenConditionalJumpInstructionThenConditionalJumpInstructionBlock() {
+        // Arrange
+        LinearIRBlock block = new LinearIRBlock();
+        LinearIRBlock then = new LinearIRBlock();
+        LinearIRBlock other = new LinearIRBlock();
+
+        var condSlot = new FrameSlot(0);
+
+        CJMP cjumpInstruction = new CJMP(condSlot, then, other);
+        block.addStmt(cjumpInstruction);
+        List<BasicBlock<IRNode>> cachedNodes = new ArrayList<>();
+
+        // Act
+        BasicBlock<IRNode> basicBlock = BasicBlock.buildFromLinearBlock(block, cachedNodes);
+
+        // Assert
+        assertTrue(basicBlock.getLastInstr() instanceof CJMP, "BasicBlock should have a conditional jump instruction when created from a LinearIRBlock with a conditional jump instruction");
+    }
+
+    @Test
+    void testBuildFromLinearBlockWhenFunctionEntryLabelThenFunctionEntryLabelBlock() {
+        // Arrange
+        LinearIRBlock block = new LinearIRBlock();
+        FuncEntryLabel funcEntryLabel = new FuncEntryLabel("main", 0, 0, null);
+        block.addStmt(funcEntryLabel);
+        List<BasicBlock<IRNode>> cachedNodes = new ArrayList<>();
+
+        // Act
+        BasicBlock<IRNode> basicBlock = BasicBlock.buildFromLinearBlock(block, cachedNodes);
+
+        // Assert
+        assertTrue(basicBlock.getLastInstr() instanceof FuncEntryLabel, "BasicBlock should have a function entry label when created from a LinearIRBlock with a function entry label");
+    }
+
+    @Test
+    void testBuildFromLinearBlockWhenLabelThenLabelBlock() {
+        // Arrange
+        LinearIRBlock block = new LinearIRBlock();
+        Label label = new Label("L1", null);
+        block.addStmt(label);
+        List<BasicBlock<IRNode>> cachedNodes = new ArrayList<>();
+
+        // Act
+        BasicBlock<IRNode> basicBlock = BasicBlock.buildFromLinearBlock(block, cachedNodes);
+
+        // Assert
+        assertTrue(basicBlock.getLastInstr() instanceof Label, "BasicBlock should have a label when created from a LinearIRBlock with a label");
+    }
+
+    // Additional tests for other methods can be added here following the same pattern.
+}