Add shift-checker test

Author: Vizonex

test/shift-checker.test.ts

@@ -0,0 +1,81 @@
+import { beforeEach, describe, it, TestContext } from 'node:test';
+import { Builder, ShiftChecker } from '../src/builder';
+
+describe ('LLParse/ShiftChecker', () => {
+  let b: Builder;
+  let sc: ShiftChecker;
+
+  beforeEach(() => {
+    b = new Builder();
+  });
+
+  it('should prohibit undefined properties', (t: TestContext) => {
+    const lshift = b.lshift("undefined", 1);
+    const start = b.node('start');
+        
+    start
+      .otherwise(lshift);
+    lshift.skipTo(start);
+    sc = new ShiftChecker(b.properties);
+
+    t.assert.throws(() => {   
+      sc.check(start);
+    }, /has not been defined for.*undefined/)
+  });
+
+  it('should detect overflowing bits', (t: TestContext) => {
+    const rshift = b.rshift("defined", 8);
+    const start = b.node('start');
+        
+    b.property('i8', "defined");
+        
+    start
+      .otherwise(rshift);
+    rshift.skipTo(start);
+
+
+    sc = new ShiftChecker(b.properties);
+    t.assert.throws(() => {   
+      sc.check(start);
+    }, /and will cause node .* to overflow./);
+
+  });
+
+  it('should detect inapproperate types', (t: TestContext) => {
+    const rshift = b.rshift("defined", 8);
+    const start = b.node('start');
+        
+    b.property('ptr', "defined");
+        
+    start
+      .otherwise(rshift);
+    rshift.skipTo(start);
+
+
+    sc = new ShiftChecker(b.properties);
+    t.assert.throws(() => {   
+      sc.check(start);
+    }, /defined cannot be provided to ".*" because field was defined as a "ptr"/);
+  });
+
+  it('should allow types that are smaller than itself', (t: TestContext) => {
+    const rshift = b.rshift("defined", 2);
+    const start = b.node('start');
+        
+    /* hypothetically let's say we have an uint32_t in C but we only 
+        need to pack a i16 bit integer, this is valid use-case because we can safely
+        back it even if the property is bigger than itself. */
+    b.property('i32', "defined");
+        
+    start
+      .otherwise(rshift);
+    rshift.skipTo(start);
+
+
+    sc = new ShiftChecker(b.properties);
+    t.assert.doesNotThrow(() => sc.check(start));
+  });
+
+
+
+})