From 84d900443e88f830bdbef6f4c485c543dea94082 Mon Sep 17 00:00:00 2001
From: Philip O Toole <philip.otoole@yahoo.com>
Date: Mon, 31 Oct 2016 16:16:30 -0400
Subject: [PATCH] Unit test, and correct, stack

---
 sql/parser.go      |  2 +-
 sql/parser_test.go | 52 ++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 53 insertions(+), 1 deletion(-)

diff --git a/sql/parser.go b/sql/parser.go
index 5f512583..ba82a7e4 100644
--- a/sql/parser.go
+++ b/sql/parser.go
@@ -25,7 +25,7 @@ func (s *stack) pop() rune {
 		return rune(0)
 	}
 	c := s.c[len(s.c)-1]
-	s.c = s.c[:len(s.c)]
+	s.c = s.c[:len(s.c)-1]
 	return c
 }
 
diff --git a/sql/parser_test.go b/sql/parser_test.go
index d92ffd14..e035b963 100644
--- a/sql/parser_test.go
+++ b/sql/parser_test.go
@@ -10,3 +10,55 @@ func Test_ScannerNew(t *testing.T) {
 		t.Fatalf("failed to create basic Scanner")
 	}
 }
+
+func Test_stackEmpty(t *testing.T) {
+	s := newStack()
+	if !s.empty() {
+		t.Fatal("new stack is not empty")
+	}
+
+	if s.peek() != rune(0) {
+		t.Fatal("peek of empty stack does not return correct value")
+	}
+}
+
+func Test_stackSingle(t *testing.T) {
+	s := newStack()
+	s.push('x')
+	if s.empty() {
+		t.Fatal("non-empty stack marked as empty")
+	}
+
+	if s.peek() != 'x' {
+		t.Fatal("peek of single stack does not return correct value")
+	}
+
+	if s.pop() != 'x' {
+		t.Fatal("pop of single stack does not return correct value")
+	}
+
+	if !s.empty() {
+		t.Fatal("popped stack is not empty")
+	}
+}
+
+func Test_stackMulti(t *testing.T) {
+	s := newStack()
+	s.push('x')
+	s.push('y')
+	s.push('z')
+
+	if s.pop() != 'z' {
+		t.Fatal("pop of 1st multi stack does not return correct value")
+	}
+	if s.pop() != 'y' {
+		t.Fatal("pop of 2nd multi stack does not return correct value")
+	}
+	if s.pop() != 'x' {
+		t.Fatal("pop of 3rd multi stack does not return correct value")
+	}
+
+	if !s.empty() {
+		t.Fatal("popped multi stack is not empty")
+	}
+}