test: add unit tests for Operations.Show() with diverse stack types

Expand operations_stack_test.go from 1 test to 10 tests covering:
- Empty stack returns 'Stack is empty'
- Boolean values display as 'true'/'false'
- Symbols display as ':name' (prefix with colon)
- StringNum values display their string content
- Mixed types (bool, symbol, string, number, metric) in one stack
- Multiple metric values with different suffixes (Mbps, hr)
- Rational numbers (Rat) display correctly
- Rational booleans display as 'true'/'false'
- Stack values order (bottom-to-top)
- Existing metric suffix test (Cool vs non-Cool)

1 files changed, 214 insertions, 0 deletions

diff --git a/internal/rpn/operations_stack_test.go b/internal/rpn/operations_stack_test.go
index f31357b..7c0252c 100644
--- a/internal/rpn/operations_stack_test.go
+++ b/internal/rpn/operations_stack_test.go
@@ -36,3 +36,217 @@ func TestShowWithMetrics(t *testing.T) {
 		t.Errorf("expected '5.5Mbps' in result, got: %s", result)
 	}
 }
+
+func TestShowEmptyStack(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+	if result != "Stack is empty" {
+		t.Errorf("Show(empty) = %q, want 'Stack is empty'", result)
+	}
+}
+
+func TestShowWithBooleanValues(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+
+	stack.Push(NewFloatFromBool(true))
+	stack.Push(NewFloatFromBool(false))
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !strings.Contains(result, "true") {
+		t.Errorf("expected 'true' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "false") {
+		t.Errorf("expected 'false' in result, got: %s", result)
+	}
+}
+
+func TestShowWithSymbols(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+
+	stack.Push(NewSymbol("x"))
+	stack.Push(NewSymbol("counter"))
+	stack.Push(NewFloat(42))
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !strings.Contains(result, ":x") {
+		t.Errorf("expected ':x' in result, got: %s", result)
+	}
+	if !strings.Contains(result, ":counter") {
+		t.Errorf("expected ':counter' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "42") {
+		t.Errorf("expected '42' in result, got: %s", result)
+	}
+}
+
+func TestShowWithStringNum(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+
+	stack.Push(NewStringNum("hello"))
+	stack.Push(NewFloat(10))
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !strings.Contains(result, "hello") {
+		t.Errorf("expected 'hello' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "10") {
+		t.Errorf("expected '10' in result, got: %s", result)
+	}
+}
+
+func TestShowWithMixedTypes(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+	reg := GetMetricRegistry()
+
+	mbps, _ := reg.Find("Mbps")
+
+	// Push various types: number, bool, symbol, string, metric number
+	stack.Push(NewFloat(42))
+	stack.Push(NewFloatFromBool(true))
+	stack.Push(NewSymbol("x"))
+	stack.Push(NewStringNum("hello"))
+	stack.Push(NewFloatWithMetric(100, mbps))
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// Verify all types appear in output
+	if !strings.Contains(result, "42") {
+		t.Errorf("expected '42' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "true") {
+		t.Errorf("expected 'true' in result, got: %s", result)
+	}
+	if !strings.Contains(result, ":x") {
+		t.Errorf("expected ':x' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "hello") {
+		t.Errorf("expected 'hello' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "100Mbps") {
+		t.Errorf("expected '100Mbps' in result, got: %s", result)
+	}
+}
+
+func TestShowWithMultipleMetrics(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+	reg := GetMetricRegistry()
+
+	mbps, _ := reg.Find("Mbps")
+	hrs, _ := reg.Find("hr")
+
+	stack.Push(NewFloatWithMetric(100, mbps))
+	stack.Push(NewFloatWithMetric(50, mbps))
+	stack.Push(NewFloatWithMetric(2.5, hrs))
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !strings.Contains(result, "100Mbps") {
+		t.Errorf("expected '100Mbps' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "50Mbps") {
+		t.Errorf("expected '50Mbps' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "2.5hr") {
+		t.Errorf("expected '2.5hr' in result, got: %s", result)
+	}
+}
+
+func TestShowWithRat(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+
+	// Rational numbers
+	rat := NewRat(0.5)
+	stack.Push(rat)
+	stack.Push(NewFloat(10))
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !strings.Contains(result, "0.5") {
+		t.Errorf("expected '0.5' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "10") {
+		t.Errorf("expected '10' in result, got: %s", result)
+	}
+}
+
+func TestShowWithRatFromBool(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+
+	stack.Push(NewRatFromBool(true))
+	stack.Push(NewRatFromBool(false))
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	if !strings.Contains(result, "true") {
+		t.Errorf("expected 'true' in result, got: %s", result)
+	}
+	if !strings.Contains(result, "false") {
+		t.Errorf("expected 'false' in result, got: %s", result)
+	}
+}
+
+func TestShowValuesOrder(t *testing.T) {
+	vars := NewVariables()
+	ops := NewOperations(vars)
+	stack := NewStack()
+
+	// Push in order: 1, 2, 3
+	stack.Push(NewFloat(1))
+	stack.Push(NewFloat(2))
+	stack.Push(NewFloat(3))
+
+	result, err := ops.Show(stack)
+	if err != nil {
+		t.Fatalf("unexpected error: %v", err)
+	}
+
+	// Show uses stack.Values() which is bottom-to-top, so "1 2 3"
+	expected := "1 2 3"
+	if result != expected {
+		t.Errorf("Show = %q, want %q", result, expected)
+	}
+}