From bfef65763c511dbfd43799a73c73933888c50a0f Mon Sep 17 00:00:00 2001
From: "Peter A. Bigot" <pab@pabigot.com>
Date: Sat, 23 Jan 2016 10:24:02 -0600
Subject: [PATCH] Layout: refine exceptions

Change a few TypeError to RangeError, and finesse the fact that some
TypeErrors might be unacceptable values.

Closes #12.
---
 lib/Layout.js      | 16 ++++++++--------
 test/LayoutTest.js |  8 ++++----
 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/lib/Layout.js b/lib/Layout.js
index c615155..819b9c3 100644
--- a/lib/Layout.js
+++ b/lib/Layout.js
@@ -382,7 +382,7 @@ function GreedyCount(elementSpan, property) {
     elementSpan = 1;
   }
   if ((!Number.isInteger(elementSpan)) || (0 >= elementSpan)) {
-    throw new TypeError('elementSpan must be a positive integer');
+    throw new TypeError('elementSpan must be a (positive) integer');
   }
   ExternalLayout.call(this, -1, property);
 
@@ -500,7 +500,7 @@ OffsetLayout.prototype.encode = function(src, b, offset) {
 function UInt(span, property) {
   Layout.call(this, span, property);
   if (6 < this.span) {
-    throw new TypeError('span must not exceed 6 bytes');
+    throw new RangeError('span must not exceed 6 bytes');
   }
   Object.freeze(this);
 }
@@ -540,7 +540,7 @@ UInt.prototype.encode = function(src, b, offset) {
 function UIntBE(span, property) {
   Layout.call(this, span, property);
   if (6 < this.span) {
-    throw new TypeError('span must not exceed 6 bytes');
+    throw new RangeError('span must not exceed 6 bytes');
   }
   Object.freeze(this);
 }
@@ -580,7 +580,7 @@ UIntBE.prototype.encode = function(src, b, offset) {
 function Int(span, property) {
   Layout.call(this, span, property);
   if (6 < this.span) {
-    throw new TypeError('span must not exceed 6 bytes');
+    throw new RangeError('span must not exceed 6 bytes');
   }
   Object.freeze(this);
 }
@@ -620,7 +620,7 @@ Int.prototype.encode = function(src, b, offset) {
 function IntBE(span, property) {
   Layout.call(this, span, property);
   if (6 < this.span) {
-    throw new TypeError('span must not exceed 6 bytes');
+    throw new RangeError('span must not exceed 6 bytes');
   }
   Object.freeze(this);
 }
@@ -1617,7 +1617,7 @@ function VariantLayout(union,
     throw new TypeError('union must be a Union');
   }
   if ((!Number.isInteger(variant)) || (0 > variant)) {
-    throw new TypeError('variant must be a non-negative integer');
+    throw new TypeError('variant must be a (non-negative) integer');
   }
   if (!(layout instanceof Layout)) {
     throw new TypeError('layout must be a Layout');
@@ -1765,7 +1765,7 @@ function BitStructure(word, msb, property) {
     throw new TypeError('word must be a UInt or UIntBE layout');
   }
   if (4 < word.span) {
-    throw new Error('word cannot exceed 32 bits');
+    throw new RangeError('word cannot exceed 32 bits');
   }
   Layout.call(this, word.span, property);
 
@@ -2066,7 +2066,7 @@ Blob.prototype.encode = function(src, b, offset) {
   }
   if (!((src instanceof Buffer)
          && (span === src.length))) {
-    throw new Error('Blob.encode requires length ' + span + ' Buffer as src');
+    throw new Error('Blob.encode requires (length ' + span + ') Buffer as src');
   }
   if ((offset + span) > b.length) {
     throw new RangeError('encoding overruns Buffer');
diff --git a/test/LayoutTest.js b/test/LayoutTest.js
index 3fab90c..18a2ea2 100644
--- a/test/LayoutTest.js
+++ b/test/LayoutTest.js
@@ -113,7 +113,7 @@ suite('Layout', function() {
       assert.equal(0xA534, d.decode(b, 2));
     });
     test('invalid ctor', function() {
-      assert.throws(function() { new lo.UInt(8); }, TypeError);
+      assert.throws(function() { new lo.UInt(8); }, RangeError);
     });
   });
   suite('UIntBE', function() {
@@ -176,7 +176,7 @@ suite('Layout', function() {
       assert.equal(0x34A5, d.decode(b, 2));
     });
     test('invalid ctor', function() {
-      assert.throws(function() { new lo.UIntBE(8); }, TypeError);
+      assert.throws(function() { new lo.UIntBE(8); }, RangeError);
     });
   });
   suite('Int', function() {
@@ -255,7 +255,7 @@ suite('Layout', function() {
       assert.equal(lo.u48be().decode(b), 0x8720f279b78f);
     });
     test('invalid ctor', function() {
-      assert.throws(function() { new lo.Int(8); }, TypeError);
+      assert.throws(function() { new lo.Int(8); }, RangeError);
     });
   });
   suite('IntBE', function() {
@@ -328,7 +328,7 @@ suite('Layout', function() {
       assert.equal(lo.u48().decode(b), 0x8720f279b78f);
     });
     test('invalid ctor', function() {
-      assert.throws(function() { new lo.IntBE(8, 'u64'); }, TypeError);
+      assert.throws(function() { new lo.IntBE(8, 'u64'); }, RangeError);
     });
   });
   test('RoundedUInt64', function() {