From ae31e38c8b3e6225ceba4ed81fc4666ad1c6b094 Mon Sep 17 00:00:00 2001
From: Klaus Post <klauspost@gmail.com>
Date: Thu, 25 Oct 2018 11:09:54 +0200
Subject: [PATCH 1/2] Add RequestExcludeHeaderFunc for easy upgrade

To make a v2 -> v3 upgrade easier we can add a similar function that can filter request headers with the same signature as before.
---
 request.go      | 25 +++++++++++++++++++++++++
 request_test.go | 29 +++++++++++++++++++++++++++++
 2 files changed, 54 insertions(+)

diff --git a/request.go b/request.go
index abd0350..25e054a 100644
--- a/request.go
+++ b/request.go
@@ -46,6 +46,31 @@ func RequestDeleteHeaderKeys(keys ...string) RequestFilter {
 	}
 }
 
+// RequestExcludeHeaderFunc is a hook function that is used to filter the Header.
+//
+// Typically this can be used to remove / amend undesirable custom headers from the request.
+//
+// For instance, if your application sends requests with a timestamp held in a custom header,
+// you likely want to exclude it from the comparison to ensure that the request headers are
+// considered a match with those saved on the cassette's track.
+//
+// Parameters:
+//  - parameter 1 - Name of header key in the Request
+///
+// Return value:
+// true - exclude header key from comparison
+// false - retain header key for comparison
+func RequestExcludeHeaderFunc(fn func(key string) bool) RequestFilter {
+	return func(req Request) Request {
+		for key := range req.Header {
+			if fn(key) {
+				req.Header.Del(key)
+			}
+		}
+		return req
+	}
+}
+
 // OnMethod will return a new filter that will only apply 'r'
 // if the method of the request matches.
 // Original filter is unmodified.
diff --git a/request_test.go b/request_test.go
index d3576ae..0b2ba3b 100644
--- a/request_test.go
+++ b/request_test.go
@@ -93,6 +93,35 @@ func TestRequestDeleteHeaderKeys(t *testing.T) {
 	}
 }
 
+func TestRequestExcludeHeaderFunc(t *testing.T) {
+	req := requestTestBase()
+	req.Header.Add("another-header", "yeah")
+	header1, header2 := textproto.CanonicalMIMEHeaderKey("a-header"), textproto.CanonicalMIMEHeaderKey("another-header")
+
+	// We expect both headers to be checked.
+	want := map[string]struct{}{header1:{}, header2: {}}
+	r := RequestExcludeHeaderFunc(func(key string) bool {
+		_, ok := want[key]
+		if !ok {
+			t.Errorf("got unexpected key %q", key)
+		}
+		// Delete so we check we only get key once.
+		delete(want, key)
+		// Delete 'a-header'
+		return header1 == key
+	})
+	req = r(req)
+	if len(want) > 0 {
+		t.Errorf("header was not checked: %v", want)
+	}
+	if len(req.Header) != 1 {
+		t.Fatalf("unexpected header count, want one: %v", req.Header)
+	}
+	if req.Header.Get("another-header") != "yeah" {
+		t.Errorf("unexpected header value: %s", req.Header.Get("another-header"))
+	}
+}
+
 func TestRequestFilters_Add(t *testing.T) {
 	var f RequestFilters
 	f1, ok1 := mustCallRequestFilterOnce(t)

From 1df4573b6d97f32cc44f611441acd0f49c7c278a Mon Sep 17 00:00:00 2001
From: seborama <seb.d.albion@outlook.com>
Date: Thu, 25 Oct 2018 19:48:01 +0100
Subject: [PATCH 2/2] Added deprecation details to RequestExcludeHeaderFunc

---
 request.go | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/request.go b/request.go
index 25e054a..7745a29 100644
--- a/request.go
+++ b/request.go
@@ -56,10 +56,12 @@ func RequestDeleteHeaderKeys(keys ...string) RequestFilter {
 //
 // Parameters:
 //  - parameter 1 - Name of header key in the Request
-///
+//
 // Return value:
 // true - exclude header key from comparison
 // false - retain header key for comparison
+//
+// Deprecated - This function will be removed on or after April 25th 2019
 func RequestExcludeHeaderFunc(fn func(key string) bool) RequestFilter {
 	return func(req Request) Request {
 		for key := range req.Header {