From 942efdbe4723659a1299833334ccb5abf3e3a118 Mon Sep 17 00:00:00 2001
From: Daniel Hensby <git@hens.by>
Date: Sat, 17 Sep 2022 10:02:24 +0100
Subject: [PATCH 1/2] Add header extraction test based on spec

---
 src/httpbis/index.ts    |  9 ++++-----
 test/httpbis/httpbis.ts | 36 +++++++++++++++++++++---------------
 2 files changed, 25 insertions(+), 20 deletions(-)

diff --git a/src/httpbis/index.ts b/src/httpbis/index.ts
index 1830ea5..8aaa2f2 100644
--- a/src/httpbis/index.ts
+++ b/src/httpbis/index.ts
@@ -25,11 +25,10 @@ export function extractHeader({ headers }: RequestLike | ResponseLike, header: s
     if (!allowMissing && !key) {
         throw new Error(`Unable to extract header "${header}" from message`);
     }
-    let val = key ? headers[key] ?? '' : '';
-    if (Array.isArray(val)) {
-        val = val.join(', ');
-    }
-    return val.toString().replace(/\s+/g, ' ');
+    const val = key ? headers[key] ?? '' : '';
+    return (!Array.isArray(val) ? [val] : val).map((v) => {
+        return v.toString().trim().replace(/\n+\s*/g, ' ');
+    }).join(', ');
 }
 
 function populateDefaultParameters(parameters: Parameters) {
diff --git a/test/httpbis/httpbis.ts b/test/httpbis/httpbis.ts
index 3dd5fc4..ed2c1aa 100644
--- a/test/httpbis/httpbis.ts
+++ b/test/httpbis/httpbis.ts
@@ -5,22 +5,28 @@ import { expect } from 'chai';
 describe('httpbis', () => {
     describe('.extractHeader', () => {
         const headers = {
-            'testheader': 'test',
-            'test-header-1': 'test1',
-            'Test-Header-2': 'test2',
-            'test-Header-3': 'test3',
-            'TEST-HEADER-4': 'test4',
+            'Host': 'www.example.com',
+            'Date': 'Tue, 20 Apr 2021 02:07:56 GMT',
+            'X-OWS-Header': '  Leading and trailing whitespace. ',
+            'X-Obs-Fold-Header': 'Obsolete\nline folding.',
+            'Cache-Control': ['max-age=60', '   must-revalidate'],
+            'Example-Dict': ' a=1,    b=2;x=1;y=2,   c=(a   b   c)',
         };
-        Object.entries(headers).forEach(([headerName, expectedValue]) => {
-            it(`successfully extracts a matching header (${headerName})`, () => {
-                expect(extractHeader({ headers } as unknown as RequestLike, headerName)).to.equal(expectedValue);
-            });
-            it(`successfully extracts a lower cased header (${headerName})`, () => {
-                expect(extractHeader({ headers } as unknown as RequestLike, headerName.toLowerCase())).to.equal(expectedValue);
-            });
-            it(`successfully extracts an upper cased header (${headerName})`, () => {
-                expect(extractHeader({ headers } as unknown as RequestLike, headerName.toUpperCase())).to.equal(expectedValue);
-            });
+        it('correctly extracts headers', () => {
+            const expected = {
+                'host': 'www.example.com',
+                'date': 'Tue, 20 Apr 2021 02:07:56 GMT',
+                'x-ows-header': 'Leading and trailing whitespace.',
+                'x-obs-fold-header': 'Obsolete line folding.',
+                'cache-control': 'max-age=60, must-revalidate',
+                'example-dict': 'a=1,    b=2;x=1;y=2,   c=(a   b   c)',
+            };
+            const parsed = Object.keys(headers).reduce((accum, name) => {
+                return Object.assign(accum, {
+                    [name.toLowerCase()]: extractHeader({ headers } as unknown as RequestLike, name),
+                });
+            }, {});
+            expect(parsed).to.deep.equal(expected);
         });
         it('allows missing headers to return by default', () => {
             expect(extractHeader({ headers } as unknown as RequestLike, 'missing')).to.equal('');

From 14aa867a782e8b9e2b302750123efc1e5ccc6ce0 Mon Sep 17 00:00:00 2001
From: Daniel Hensby <git@hens.by>
Date: Sat, 17 Sep 2022 10:10:46 +0100
Subject: [PATCH 2/2] Empty/missing headers should be extracted as single
 spacce

---
 src/httpbis/index.ts    | 2 +-
 test/httpbis/httpbis.ts | 8 ++++++--
 2 files changed, 7 insertions(+), 3 deletions(-)

diff --git a/src/httpbis/index.ts b/src/httpbis/index.ts
index 8aaa2f2..fd180cc 100644
--- a/src/httpbis/index.ts
+++ b/src/httpbis/index.ts
@@ -27,7 +27,7 @@ export function extractHeader({ headers }: RequestLike | ResponseLike, header: s
     }
     const val = key ? headers[key] ?? '' : '';
     return (!Array.isArray(val) ? [val] : val).map((v) => {
-        return v.toString().trim().replace(/\n+\s*/g, ' ');
+        return v.toString().trim().replace(/\n+\s*/g, ' ') || ' ';
     }).join(', ');
 }
 
diff --git a/test/httpbis/httpbis.ts b/test/httpbis/httpbis.ts
index ed2c1aa..7322b37 100644
--- a/test/httpbis/httpbis.ts
+++ b/test/httpbis/httpbis.ts
@@ -28,14 +28,18 @@ describe('httpbis', () => {
             }, {});
             expect(parsed).to.deep.equal(expected);
         });
+        it('extracts an empty header', () => {
+            const parsed = extractHeader({ headers: { 'x-empty-header': '' } } as unknown as RequestLike, 'x-empty-header');
+            expect(parsed).to.equal(' ');
+        });
         it('allows missing headers to return by default', () => {
-            expect(extractHeader({ headers } as unknown as RequestLike, 'missing')).to.equal('');
+            expect(extractHeader({ headers } as unknown as RequestLike, 'missing')).to.equal(' ');
         });
         it('throws on missing headers', () => {
             expect(() => extractHeader({ headers } as unknown as RequestLike, 'missing', { allowMissing: false })).to.throw(Error, 'Unable to extract header "missing" from message');
         });
         it('does not throw on missing headers', () => {
-            expect(extractHeader({ headers } as unknown as RequestLike, 'missing', { allowMissing: true })).to.equal('');
+            expect(extractHeader({ headers } as unknown as RequestLike, 'missing', { allowMissing: true })).to.equal(' ');
         });
     });
     describe('.extractComponent', () => {