From cdbc6b2cfb22070f2330e7e37eb61a79e21f0c4d Mon Sep 17 00:00:00 2001
From: Dylan Piercey <dpiercey@ebay.com>
Date: Fri, 12 Aug 2022 09:33:24 -0700
Subject: [PATCH] fix: improve missing attribute value error (#134)

---
 .changeset/moody-donuts-enjoy.md                    |  5 +++++
 .../__snapshots__/attr-value-missing.expected.txt   |  6 ++++++
 .../fixtures/attr-value-missing/input.marko         |  1 +
 src/states/ATTRIBUTE.ts                             | 13 ++++++++++---
 4 files changed, 22 insertions(+), 3 deletions(-)
 create mode 100644 .changeset/moody-donuts-enjoy.md
 create mode 100644 src/__tests__/fixtures/attr-value-missing/__snapshots__/attr-value-missing.expected.txt
 create mode 100644 src/__tests__/fixtures/attr-value-missing/input.marko

diff --git a/.changeset/moody-donuts-enjoy.md b/.changeset/moody-donuts-enjoy.md
new file mode 100644
index 00000000..801b6479
--- /dev/null
+++ b/.changeset/moody-donuts-enjoy.md
@@ -0,0 +1,5 @@
+---
+"htmljs-parser": patch
+---
+
+Improve missing attribute error when the tag is immediately closed without the attribute value.
diff --git a/src/__tests__/fixtures/attr-value-missing/__snapshots__/attr-value-missing.expected.txt b/src/__tests__/fixtures/attr-value-missing/__snapshots__/attr-value-missing.expected.txt
new file mode 100644
index 00000000..27ab9c88
--- /dev/null
+++ b/src/__tests__/fixtures/attr-value-missing/__snapshots__/attr-value-missing.expected.txt
@@ -0,0 +1,6 @@
+1╭─ <span class=>
+ │  ││    │     ╰─ error(INVALID_ATTRIBUTE_VALUE:Missing value for attribute)
+ │  ││    ╰─ attrName "class"
+ │  │╰─ tagName "span"
+ ╰─ ╰─ openTagStart
+2╰─ 
\ No newline at end of file
diff --git a/src/__tests__/fixtures/attr-value-missing/input.marko b/src/__tests__/fixtures/attr-value-missing/input.marko
new file mode 100644
index 00000000..e73cd64c
--- /dev/null
+++ b/src/__tests__/fixtures/attr-value-missing/input.marko
@@ -0,0 +1 @@
+<span class=>
diff --git a/src/states/ATTRIBUTE.ts b/src/states/ATTRIBUTE.ts
index a5adfab6..5418ff2a 100644
--- a/src/states/ATTRIBUTE.ts
+++ b/src/states/ATTRIBUTE.ts
@@ -266,15 +266,22 @@ function shouldTerminateHtmlAttrName(code: number, data: string, pos: number) {
   }
 }
 
-function shouldTerminateHtmlAttrValue(code: number, data: string, pos: number) {
+function shouldTerminateHtmlAttrValue(
+  this: STATE.ExpressionMeta,
+  code: number,
+  data: string,
+  pos: number
+) {
   switch (code) {
     case CODE.COMMA:
       return true;
     case CODE.FORWARD_SLASH:
       return data.charCodeAt(pos + 1) === CODE.CLOSE_ANGLE_BRACKET;
-    // Add special case for =>
     case CODE.CLOSE_ANGLE_BRACKET:
-      return data.charCodeAt(pos - 1) !== CODE.EQUAL;
+      // Add special case for =>
+      // We only look behind to match => if we're not at the start of the expression
+      // otherwise this would match something like "<span class=>".
+      return pos === this.start || data.charCodeAt(pos - 1) !== CODE.EQUAL;
     default:
       return false;
   }