fix(proxy-rewrite): when conf.headers are missing,conf.method can make effect

[liangliang4ward]

What this PR does / why we need it:

when conf.headers are missing,conf.method can make effect

Pre-submission checklist:

• Did you explain what problem does this PR solve? Or what new features have been added?
• Have you added corresponding test cases?
• Have you modified the corresponding document?
• Is this PR backward compatible? If it is not backward compatible, please discuss on the mailing list first

[tokers]

@liangliang4ward Better to add some test cases to cover it.

[spacewander]

The fix LGTM.

You can learn how to write tests via https://github.com/apache/apisix/blob/master/docs/en/latest/internal/testing-framework.md and the current test

apisix/t/plugin/proxy-rewrite3.t

Lines 87 to 129 in ebe91aa

	=== TEST 3: set route(update rewrite method)
	--- config
	location /t {
	content_by_lua_block {
	local t = require("lib.test_admin").test
	local code, body = t('/apisix/admin/routes/1',
	ngx.HTTP_PUT,
	[[{
	"methods": ["GET"],
	"plugins": {
	"proxy-rewrite": {
	"uri": "/plugin_proxy_rewrite",
	"method": "GET",
	"scheme": "http",
	"host": "apisix.iresty.com"
	}
	},
	"upstream": {
	"nodes": {
	"127.0.0.1:1980": 1
	},
	"type": "roundrobin"
	},
	"uri": "/hello"
	}]]
	)
	if code >= 300 then
	ngx.status = code
	end
	ngx.say(body)
	}
	}
	--- response_body
	passed
	=== TEST 4: hit route(upstream uri: should be /hello)
	--- request
	GET /hello
	--- grep_error_log_out
	plugin_proxy_rewrite get method: GET

[liangliang4ward]

The fix LGTM.

You can learn how to write tests via https://github.com/apache/apisix/blob/master/docs/en/latest/internal/testing-framework.md and the current test

apisix/t/plugin/proxy-rewrite3.t

Lines 87 to 129 in ebe91aa

	=== TEST 3: set route(update rewrite method)
	--- config
	location /t {
	content_by_lua_block {
	local t = require("lib.test_admin").test
	local code, body = t('/apisix/admin/routes/1',
	ngx.HTTP_PUT,
	[[{
	"methods": ["GET"],
	"plugins": {
	"proxy-rewrite": {
	"uri": "/plugin_proxy_rewrite",
	"method": "GET",
	"scheme": "http",
	"host": "apisix.iresty.com"
	}
	},
	"upstream": {
	"nodes": {
	"127.0.0.1:1980": 1
	},
	"type": "roundrobin"
	},
	"uri": "/hello"
	}]]
	)
	if code >= 300 then
	ngx.status = code
	end
	ngx.say(body)
	}
	}
	--- response_body
	passed
	=== TEST 4: hit route(upstream uri: should be /hello)
	--- request
	GET /hello
	--- grep_error_log_out
	plugin_proxy_rewrite get method: GET

in proxy-rewrite3.t ,I thought the TEST 2 case according to the original code, it should not succeed。

[spacewander]

The fix LGTM.
You can learn how to write tests via https://github.com/apache/apisix/blob/master/docs/en/latest/internal/testing-framework.md and the current test

apisix/t/plugin/proxy-rewrite3.t

Lines 87 to 129 in ebe91aa

	=== TEST 3: set route(update rewrite method)
	--- config
	location /t {
	content_by_lua_block {
	local t = require("lib.test_admin").test
	local code, body = t('/apisix/admin/routes/1',
	ngx.HTTP_PUT,
	[[{
	"methods": ["GET"],
	"plugins": {
	"proxy-rewrite": {
	"uri": "/plugin_proxy_rewrite",
	"method": "GET",
	"scheme": "http",
	"host": "apisix.iresty.com"
	}
	},
	"upstream": {
	"nodes": {
	"127.0.0.1:1980": 1
	},
	"type": "roundrobin"
	},
	"uri": "/hello"
	}]]
	)
	if code >= 300 then
	ngx.status = code
	end
	ngx.say(body)
	}
	}
	--- response_body
	passed
	=== TEST 4: hit route(upstream uri: should be /hello)
	--- request
	GET /hello
	--- grep_error_log_out
	plugin_proxy_rewrite get method: GET

in proxy-rewrite3.t ,I thought the TEST 2 case according to the original code, it should not succeed。

Let's add a test to prove your suspect. The test is passed in the CI.

[liangliang4ward]

The fix LGTM.
You can learn how to write tests via https://github.com/apache/apisix/blob/master/docs/en/latest/internal/testing-framework.md and the current test

apisix/t/plugin/proxy-rewrite3.t

Lines 87 to 129 in ebe91aa

	=== TEST 3: set route(update rewrite method)
	--- config
	location /t {
	content_by_lua_block {
	local t = require("lib.test_admin").test
	local code, body = t('/apisix/admin/routes/1',
	ngx.HTTP_PUT,
	[[{
	"methods": ["GET"],
	"plugins": {
	"proxy-rewrite": {
	"uri": "/plugin_proxy_rewrite",
	"method": "GET",
	"scheme": "http",
	"host": "apisix.iresty.com"
	}
	},
	"upstream": {
	"nodes": {
	"127.0.0.1:1980": 1
	},
	"type": "roundrobin"
	},
	"uri": "/hello"
	}]]
	)
	if code >= 300 then
	ngx.status = code
	end
	ngx.say(body)
	}
	}
	--- response_body
	passed
	=== TEST 4: hit route(upstream uri: should be /hello)
	--- request
	GET /hello
	--- grep_error_log_out
	plugin_proxy_rewrite get method: GET

in proxy-rewrite3.t ,I thought the TEST 2 case according to the original code, it should not succeed。

Let's add a test to prove your suspect. The test is passed in the CI.

this PR will to solve this issue; TEST 2 case I don't why CI will success . this is my confusion.

[liangliang4ward]

@liangliang4ward Better to add some test cases to cover it.

add a test case

[spacewander]

Merged. Thanks!