Repository: coinbase/rosetta-sdk-go
Pull request #305 (2021-03-10 22:38:24)

[Parser] Update parser.MatchOperations to do non-negative and non-positive matching
### Motivation
<!--
Does this solve a bug? Enable a new use-case? Improve an existing behavior? Concrete examples are helpful here.
-->
There are several cases where the matcher may expect opposite amounts but zero amounts are sent. Instead of having clients implement additional fallback logic, we want to update the sdk to be able to handle non-negative or non-positive scenarios when expecting opposite amounts.

### Solution
<!--
What is the solution here from a high level. What are the key technical decisions and why were they made?
-->

Add a new OppositeOrZeroAmounts matcher and corresponding matching logic instead of replacing the existing OppositeAmounts matcher. This way, this isn't a breaking change for other users of the library.

Add PositiveAmountSignOrZero and NegativeAmountSignOrZero amount signs for amount matching when using  `OppositeOrZeroAmounts`. We could just use AnyAmountSign, but these additional signs let us get the same order of matches as with `OppositeAmounts`. 

### Open questions
<!--
(optional) Any open questions or feedback on design desired?
-->
1. Does the order of elements in the Matches array returned by `MatchOperations` matter? 


Patch:
diff --git a/fetcher/configuration.go b/fetcher/configuration.go
index 3df344b..77b0dda 100644
--- a/fetcher/configuration.go
+++ b/fetcher/configuration.go
@@ -73,7 +73,7 @@ func WithInsecureTLS() Option {
 // WithTimeout overrides the default HTTP timeout.
 func WithTimeout(timeout time.Duration) Option {
 	return func(f *Fetcher) {
-		f.httpTimeout = timeout
+		f.rosettaClient.GetConfig().HTTPClient.Timeout = timeout
 	}
 }
 
diff --git a/fetcher/fetcher.go b/fetcher/fetcher.go
index b13bf41..122a11d 100644
--- a/fetcher/fetcher.go
+++ b/fetcher/fetcher.go
@@ -74,7 +74,6 @@ type Fetcher struct {
 	retryElapsedTime time.Duration
 	insecureTLS      bool
 	forceRetry       bool
-	httpTimeout      time.Duration
 
 	// connectionSemaphore is used to limit the
 	// number of concurrent requests we make.
@@ -90,7 +89,6 @@ func New(
 		maxConnections:   DefaultMaxConnections,
 		maxRetries:       DefaultRetries,
 		retryElapsedTime: DefaultElapsedTime,
-		httpTimeout:      DefaultHTTPTimeout,
 	}
 
 	// Override defaults with any provided options
@@ -108,7 +106,7 @@ func New(
 		defaultTransport.MaxIdleConns = f.maxConnections
 		defaultTransport.MaxIdleConnsPerHost = DefaultMaxConnections
 		defaultHTTPClient := &http.Client{
-			Timeout:   f.httpTimeout,
+			Timeout:   DefaultHTTPTimeout,
 			Transport: defaultTransport,
 		}
 
diff --git a/go.sum b/go.sum
index b6f85ed..7651b05 100644
--- a/go.sum
+++ b/go.sum
@@ -14,51 +14,38 @@ github.com/Azure/go-autorest/logger v0.1.0/go.mod h1:oExouG+K6PryycPJfVSxi/koC6L
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@@ -66,7 +53,6 @@ github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA
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@@ -76,12 +62,10 @@ github.com/coreos/go-semver v0.2.0/go.mod h1:nnelYz7RCh+5ahJtPPxZlU+153eP4D4r3Ee
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@@ -104,7 +88,6 @@ github.com/envoyproxy/go-control-plane v0.9.1-0.20191026205805-5f8ba28d4473/go.m
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@@ -114,10 +97,8 @@ github.com/fsnotify/fsnotify v1.4.9/go.mod h1:znqG4EE+3YCdAaPaxE2ZRY/06pZUdp0tY4
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@@ -140,7 +121,6 @@ github.com/google/go-cmp v0.2.0/go.mod h1:oXzfMopK8JAjlY9xF4vHSVASa0yLyX7SntLO5a
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-github.com/kr/pretty v0.1.0 h1:L/CwN0zerZDmRFUapSPitk6f+Q3+0za1rQkzVuMiMFI=
 github.com/kr/pretty v0.1.0/go.mod h1:dAy3ld7l9f0ibDNOQOHHMYYIIbhfbHSm3C4ZsoJORNo=
 github.com/kr/pretty v0.2.0 h1:s5hAObm+yFO5uHYt5dYjxi2rXrsnmRpJx4OYvIWUaQs=
 github.com/kr/pretty v0.2.0/go.mod h1:ipq/a2n7PKx3OHsz4KJII5eveXtPO4qwEXGdVfWzfnI=
@@ -237,7 +213,6 @@ github.com/russross/blackfriday v1.5.2/go.mod h1:JO/DiYxRf+HjHt06OyowR9PTA263kcR
 github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/segmentio/fasthash v1.0.3 h1:EI9+KE1EwvMLBWwjpRDc+fEM+prwxDYbslddQGtrmhM=
 github.com/segmentio/fasthash v1.0.3/go.mod h1:waKX8l2N8yckOgmSsXJi7x1ZfdKZ4x7KRMzBtS3oedY=
-github.com/shirou/gopsutil v2.20.5+incompatible h1:tYH07UPoQt0OCQdgWWMgYHy3/a9bcxNpBIysykNIP7I=
 github.com/shirou/gopsutil v2.20.5+incompatible/go.mod h1:5b4v6he4MtMOwMlS0TUMTu2PcXUg8+E1lC7eC3UO/RA=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
 github.com/spaolacci/murmur3 v0.0.0-20180118202830-f09979ecbc72/go.mod h1:JwIasOWyU6f++ZhiEuf87xNszmSA2myDM2Kzu9HwQUA=
@@ -250,9 +225,7 @@ github.com/spf13/jwalterweatherman v1.0.0/go.mod h1:cQK4TGJAtQXfYWX+Ddv3mKDzgVb6
 github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
 github.com/spf13/viper v1.3.2/go.mod h1:ZiWeW+zYFKm7srdB9IoDzzZXaJaI5eL9QjNiN/DMA2s=
 github.com/status-im/keycard-go v0.0.0-20190316090335-8537d3370df4/go.mod h1:RZLeN1LMWmRsyYjvAu+I6Dm9QmlDaIIt+Y+4Kd7Tp+Q=
-github.com/steakknife/bloomfilter v0.0.0-20180922174646-6819c0d2a570 h1:gIlAHnH1vJb5vwEjIp5kBj/eu99p/bl0Ay2goiPe5xE=
 github.com/steakknife/bloomfilter v0.0.0-20180922174646-6819c0d2a570/go.mod h1:8OR4w3TdeIHIh1g6EMY5p0gVNOovcWC+1vpc7naMuAw=
-github.com/steakknife/hamming v0.0.0-20180906055917-c99c65617cd3 h1:njlZPzLwU639dk2kqnCPPv+wNjq7Xb6EfUxe/oX0/NM=
 github.com/steakknife/hamming v0.0.0-20180906055917-c99c65617cd3/go.mod h1:hpGUWaI9xL8pRQCTXQgocU38Qw1g0Us7n5PxxTwTCYU=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/objx v0.1.1 h1:2vfRuCMp5sSVIDSqO8oNnWJq7mPa6KVP3iPIwFBuy8A=
@@ -261,7 +234,6 @@ github.com/stretchr/testify v1.2.2/go.mod h1:a8OnRcib4nhh0OaRAV+Yts87kKdq0PP7pXf
 github.com/stretchr/testify v1.3.0/go.mod h1:M5WIy9Dh21IEIfnGCwXGc5bZfKNJtfHm1UVUgZn+9EI=
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=
-github.com/stretchr/testify v1.6.1 h1:hDPOHmpOpP40lSULcqw7IrRb/u7w6RpDC9399XyoNd0=
 github.com/stretchr/testify v1.6.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/stretchr/testify v1.7.0 h1:nwc3DEeHmmLAfoZucVR881uASk0Mfjw8xYJ99tb5CcY=
 github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
@@ -294,7 +266,6 @@ golang.org/x/crypto v0.0.0-20190909091759-094676da4a83/go.mod h1:yigFU9vqHzYiE8U
 golang.org/x/crypto v0.0.0-20191011191535-87dc89f01550/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
 golang.org/x/crypto v0.0.0-20200115085410-6d4e4cb37c7d/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20200510223506-06a226fb4e37/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
-golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9 h1:psW17arqaxU48Z5kZ0CQnkZWQJsqcURM6tKiBApRjXI=
 golang.org/x/crypto v0.0.0-20200622213623-75b288015ac9/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
 golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a h1:vclmkQCjlDX5OydZ9wv8rBCcS0QyQY66Mpf/7BZbInM=
 golang.org/x/crypto v0.0.0-20200820211705-5c72a883971a/go.mod h1:LzIPMQfyMNhhGPhUkYOs5KpL4U8rLKemX1yGLhDgUto=
@@ -304,7 +275,6 @@ golang.org/x/image v0.0.0-20190227222117-0694c2d4d067/go.mod h1:kZ7UVZpmo3dzQBMx
 golang.org/x/image v0.0.0-20190802002840-cff245a6509b/go.mod h1:FeLwcggjj3mMvU+oOTbSwawSJRM1uh48EjtB4UJZlP0=
 golang.org/x/lint v0.0.0-20181026193005-c67002cb31c3/go.mod h1:UVdnD1Gm6xHRNCYTkRU2/jEulfH38KcIWyp/GAMgvoE=
 golang.org/x/lint v0.0.0-20190227174305-5b3e6a55c961/go.mod h1:wehouNa3lNwaWXcvxsM5YxQ5yQlVC4a0KAMCusXpPoU=
-golang.org/x/lint v0.0.0-20190313153728-d0100b6bd8b3 h1:XQyxROzUlZH+WIQwySDgnISgOivlhjIEwaQaJEJrrN0=
 golang.org/x/lint v0.0.0-20190313153728-d0100b6bd8b3/go.mod h1:6SW0HCj/g11FgYtHlgUYUwCkIfeOF89ocIRzGO/8vkc=
 golang.org/x/mobile v0.0.0-20190312151609-d3739f865fa6/go.mod h1:z+o9i4GpDbdi3rU15maQ/Ox0txvL9dWGYEHz965HBQE=
 golang.org/x/mobile v0.0.0-20200801112145-973feb4309de/go.mod h1:skQtrUTUwhdJvXM/2KKJzY8pDgNr9I/FOMqDVRPBUS4=
@@ -321,9 +291,7 @@ golang.org/x/net v0.0.0-20190311183353-d8887717615a/go.mod h1:t9HGtf8HONx5eT2rtn
 golang.org/x/net v0.0.0-20190404232315-eb5bcb51f2a3/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/net v0.0.0-20200520004742-59133d7f0dd7/go.mod h1:qpuaurCH72eLCgpAm/N6yyVIVM9cpaDIP3A8BGJEC5A=
-golang.org/x/net v0.0.0-20200813134508-3edf25e44fcc h1:zK/HqS5bZxDptfPJNq8v7vJfXtkU7r9TLIoSr1bXaP4=
 golang.org/x/net v0.0.0-20200813134508-3edf25e44fcc/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
-golang.org/x/net v0.0.0-20200822124328-c89045814202 h1:VvcQYSHwXgi7W+TpUR6A9g6Up98WAHf3f/ulnJ62IyA=
 golang.org/x/net v0.0.0-20200822124328-c89045814202/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
 golang.org/x/net v0.0.0-20200904194848-62affa334b73 h1:MXfv8rhZWmFeqX3GNZRsd6vOLoaCHjYEX3qkRo3YBUA=
 golang.org/x/net v0.0.0-20200904194848-62affa334b73/go.mod h1:/O7V0waA8r7cgGh81Ro3o1hOxt32SMVPicZroKQ2sZA=
@@ -345,7 +313,6 @@ golang.org/x/sys v0.0.0-20191005200804-aed5e4c7ecf9/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20191120155948-bd437916bb0e/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200116001909-b77594299b42/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200223170610-d5e6a3e2c0ae/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
-golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd h1:xhmwyvizuTgC2qz7ZlMluP20uW+C3Rm0FD/WLDX8884=
 golang.org/x/sys v0.0.0-20200323222414-85ca7c5b95cd/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200519105757-fe76b779f299/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/sys v0.0.0-20200814200057-3d37ad5750ed/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
@@ -361,14 +328,12 @@ golang.org/x/tools v0.0.0-20190114222345-bf090417da8b/go.mod h1:n7NCudcB/nEzxVGm
 golang.org/x/tools v0.0.0-20190226205152-f727befe758c/go.mod h1:9Yl7xja0Znq3iFh3HoIrodX9oNMXvdceNzlUR8zjMvY=
 golang.org/x/tools v0.0.0-20190311212946-11955173bddd/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
 golang.org/x/tools v0.0.0-20190312151545-0bb0c0a6e846/go.mod h1:LCzVGOaR6xXOjkQ3onu1FJEFr0SW1gC7cKk1uF8kGRs=
-golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135 h1:5Beo0mZN8dRzgrMMkDp0jc8YXQKx9DiJ2k1dkvGsn5A=
 golang.org/x/tools v0.0.0-20190524140312-2c0ae7006135/go.mod h1:RgjU9mgBXZiqYHBnxXauZ1Gv1EHHAz9KjViQ78xBX0Q=
 golang.org/x/tools v0.0.0-20191119224855-298f0cb1881e/go.mod h1:b+2E5dAYhXwXZwtnZ6UAqBI28+e2cm9otk0dWdXHAEo=
 golang.org/x/tools v0.0.0-20200117012304-6edc0a871e69 h1:yBHHx+XZqXJBm6Exke3N7V9gnlsyXxoCPEb1yVenjfk=
 golang.org/x/tools v0.0.0-20200117012304-6edc0a871e69/go.mod h1:TB2adYChydJhpapKDTa4BR/hXlZSLoq2Wpct/0txZ28=
 golang.org/x/xerrors v0.0.0-20190717185122-a985d3407aa7/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20191011141410-1b5146add898/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
-golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543 h1:E7g+9GITq07hpfrRu66IVDexMakfv52eLZ2CXBWiKr4=
 golang.org/x/xerrors v0.0.0-20191204190536-9bdfabe68543/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1 h1:go1bK/D/BFZV2I8cIQd1NKEZ+0owSTG1fDTci4IqFcE=
 golang.org/x/xerrors v0.0.0-20200804184101-5ec99f83aff1/go.mod h1:I/5z698sn9Ka8TeJc9MKroUUfqBBauWjQqLJ2OPfmY0=
@@ -386,16 +351,13 @@ google.golang.org/protobuf v0.0.0-20200228230310-ab0ca4ff8a60/go.mod h1:cfTl7dwQ
 google.golang.org/protobuf v1.20.1-0.20200309200217-e05f789c0967/go.mod h1:A+miEFZTKqfCUM6K7xSMQL9OKL/b6hQv+e19PK+JZNE=
 google.golang.org/protobuf v1.21.0/go.mod h1:47Nbq4nVaFHyn7ilMalzfO3qCViNmqZ2kzikPIcrTAo=
 google.golang.org/protobuf v1.22.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
-google.golang.org/protobuf v1.23.0 h1:4MY060fB1DLGMB/7MBTLnwQUY6+F09GEiz6SsrNqyzM=
 google.golang.org/protobuf v1.23.0/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
 google.golang.org/protobuf v1.23.1-0.20200526195155-81db48ad09cc/go.mod h1:EGpADcykh3NcUnDUJcl1+ZksZNG86OlYog2l/sGQquU=
 google.golang.org/protobuf v1.25.0 h1:Ejskq+SyPohKW+1uil0JJMtmHCgJPJ/qWTxr8qp+R4c=
 google.golang.org/protobuf v1.25.0/go.mod h1:9JNX74DMeImyA3h4bdi1ymwjUzf21/xIlbajtzgsN7c=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6 h1:jMFz6MfLP0/4fUyZle81rXUoxOBFi19VUFKVDOQfozc=
 gopkg.in/alecthomas/kingpin.v2 v2.2.6/go.mod h1:FMv+mEhP44yOT+4EoQTLFTRgOQ1FBLkstjWtayDeSgw=
-gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
-gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127 h1:qIbj1fsPNlZgppZ+VLlY7N33q108Sa+fhmuc+sWQYwY=
 gopkg.in/check.v1 v1.0.0-20180628173108-788fd7840127/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15 h1:YR8cESwS4TdDjEe65xsg0ogRM/Nc3DYOhEAlW+xobZo=
 gopkg.in/check.v1 v1.0.0-20190902080502-41f04d3bba15/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
@@ -405,7 +367,6 @@ gopkg.in/olebedev/go-duktape.v3 v3.0.0-20200619000410-60c24ae608a6/go.mod h1:uAJ
 gopkg.in/tomb.v1 v1.0.0-20141024135613-dd632973f1e7/go.mod h1:dt/ZhP58zS4L8KSrWDmTeBkI65Dw0HsyUHuEVlX15mw=
 gopkg.in/urfave/cli.v1 v1.20.0/go.mod h1:vuBzUtMdQeixQj8LVd+/98pzhxNGQoyuPBlsXHOQNO0=
 gopkg.in/yaml.v2 v2.2.1/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.2.2 h1:ZCJp+EgiOT7lHqUV2J862kp8Qj64Jo6az82+3Td9dZw=
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.4/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
diff --git a/parser/match_operations.go b/parser/match_operations.go
index c45d5af..006e0b7 100644
--- a/parser/match_operations.go
+++ b/parser/match_operations.go
@@ -28,13 +28,19 @@ type AmountSign int
 
 const (
 	// AnyAmountSign is a positive or negative amount.
-	AnyAmountSign = iota
+	AnyAmountSign = 0
 
 	// NegativeAmountSign is a negative amount.
-	NegativeAmountSign
+	NegativeAmountSign = 1
 
 	// PositiveAmountSign is a positive amount.
-	PositiveAmountSign
+	PositiveAmountSign = 2
+
+	// PositiveOrZeroAmountSign is a positive or zero amount.
+	PositiveOrZeroAmountSign = 3
+
+	// NegativeOrZeroAmountSign is a positive or zero amount.
+	NegativeOrZeroAmountSign = 4
 
 	// oppositesLength is the only allowed number of
 	// operations to compare as opposites.
@@ -61,6 +67,14 @@ func (s AmountSign) Match(amount *types.Amount) bool {
 		return true
 	}
 
+	if s == PositiveOrZeroAmountSign && (numeric.Sign() == 1 || amount.Value == "0") {
+		return true
+	}
+
+	if s == NegativeOrZeroAmountSign && (numeric.Sign() == -1 || amount.Value == "0") {
+		return true
+	}
+
 	return false
 }
 
@@ -73,6 +87,10 @@ func (s AmountSign) String() string {
 		return "negative"
 	case PositiveAmountSign:
 		return "positive"
+	case PositiveOrZeroAmountSign:
+		return "positive or zero"
+	case NegativeOrZeroAmountSign:
+		return "negative or zero"
 	default:
 		return "invalid"
 	}
@@ -129,17 +147,22 @@ type OperationDescription struct {
 type Descriptions struct {
 	OperationDescriptions []*OperationDescription
 
-	// EqualAmounts are specified using the operation indicies of
+	// EqualAmounts are specified using the operation indices of
 	// OperationDescriptions to handle out of order matches. MatchOperations
 	// will error if all groups of operations aren't equal.
 	EqualAmounts [][]int
 
-	// OppositeAmounts are specified using the operation indicies of
+	// OppositeAmounts are specified using the operation indices of
 	// OperationDescriptions to handle out of order matches. MatchOperations
 	// will error if all groups of operations aren't opposites.
 	OppositeAmounts [][]int
 
-	// EqualAddresses are specified using the operation indicies of
+	// OppositeZeroAmounts are specified using the operation indices of
+	// OperationDescriptions to handle out of order matches. MatchOperations
+	// will error if all groups of operations aren't 0 or opposites.
+	OppositeOrZeroAmounts [][]int
+
+	// EqualAddresses are specified using the operation indices of
 	// OperationDescriptions to handle out of order matches. MatchOperations
 	// will error if all groups of operations addresses aren't equal.
 	EqualAddresses [][]int
@@ -398,6 +421,40 @@ func oppositeAmounts(a *types.Operation, b *types.Operation) error {
 	return nil
 }
 
+// oppositeOrZeroAmounts returns an error if two operations do not have opposite
+// amounts and both amounts are not zero.
+func oppositeOrZeroAmounts(a *types.Operation, b *types.Operation) error {
+	aVal, err := types.AmountValue(a.Amount)
+	if err != nil {
+		return err
+	}
+
+	bVal, err := types.AmountValue(b.Amount)
+	if err != nil {
+		return err
+	}
+
+	zero := big.NewInt(0)
+	if aVal.Cmp(zero) == 0 && bVal.Cmp(zero) == 0 {
+		return nil
+	}
+
+	if aVal.Sign() == bVal.Sign() {
+		return fmt.Errorf("%w: %s and %s", ErrOppositeAmountsSameSign, aVal.String(), bVal.String())
+	}
+
+	if aVal.CmpAbs(bVal) != 0 {
+		return fmt.Errorf(
+			"%w: %s and %s",
+			ErrOppositeAmountsAbsValMismatch,
+			aVal.String(),
+			bVal.String(),
+		)
+	}
+
+	return nil
+}
+
 // equalAddresses returns an error if a slice of operations do not have
 // equal addresses.
 func equalAddresses(ops []*types.Operation) error {
@@ -468,64 +525,81 @@ func checkOps(requests [][]int, matches []*Match, valid func([]*types.Operation)
 	return nil
 }
 
-// comparisonMatch ensures collections of *types.Operations
-// have either equal or opposite amounts.
-func comparisonMatch(
-	descriptions *Descriptions,
+// compareOppositeMatches ensures collections of *types.Operation
+// that may have opposite amounts contain valid matching amounts
+func compareOppositeMatches(
+	amountPairs [][]int,
 	matches []*Match,
+	amountChecker func(*types.Operation, *types.Operation) error,
 ) error {
-	if err := checkOps(descriptions.EqualAmounts, matches, equalAmounts); err != nil {
-		return fmt.Errorf("%w: operation amounts not equal", err)
-	}
-
-	if err := checkOps(descriptions.EqualAddresses, matches, equalAddresses); err != nil {
-		return fmt.Errorf("%w: operation addresses not equal", err)
-	}
-
-	for _, amountMatch := range descriptions.OppositeAmounts {
+	for _, amountMatch := range amountPairs {
 		if len(amountMatch) != oppositesLength { // cannot have opposites without exactly 2
 			return fmt.Errorf("cannot check opposites of %d operations", len(amountMatch))
 		}
 
 		// compare all possible pairs
 		if err := matchIndexValid(matches, amountMatch[0]); err != nil {
-			return fmt.Errorf("%w: opposite amounts comparison error", err)
+			return fmt.Errorf("%w: amounts comparison error", err)
 		}
 		if err := matchIndexValid(matches, amountMatch[1]); err != nil {
-			return fmt.Errorf("%w: opposite amounts comparison error", err)
+			return fmt.Errorf("%w: amounts comparison error", err)
 		}
 
 		match0Ops := matches[amountMatch[0]].Operations
 		match1Ops := matches[amountMatch[1]].Operations
 		if err := equalAmounts(match0Ops); err != nil {
 			return fmt.Errorf(
-				"%w: opposite amounts comparison error for match index %d",
+				"%w: amounts comparison error for match index %d",
 				err,
 				amountMatch[0],
 			)
 		}
 		if err := equalAmounts(match1Ops); err != nil {
 			return fmt.Errorf(
-				"%w: opposite amounts comparison error for match index %d",
+				"%w: amounts comparison error for match index %d",
 				err,
 				amountMatch[1],
 			)
 		}
 
-		// only need to check opposites amount for the very first operation from each
+		// only need to check amount for the very first operation from each
 		// matched operations group since we made sure all amounts within the same
 		// matched operation group are the same
-		if err := oppositeAmounts(
+		if err := amountChecker(
 			match0Ops[0],
 			match1Ops[0],
 		); err != nil {
-			return fmt.Errorf("%w: amounts not opposites", err)
+			return fmt.Errorf("%w: amounts do not match the amountChecker function", err)
 		}
 	}
 
 	return nil
 }
 
+// comparisonMatch ensures collections of *types.Operation
+// have either equal or opposite amounts.
+func comparisonMatch(
+	descriptions *Descriptions,
+	matches []*Match,
+) error {
+	if err := checkOps(descriptions.EqualAmounts, matches, equalAmounts); err != nil {
+		return fmt.Errorf("%w: operation amounts not equal", err)
+	}
+
+	if err := checkOps(descriptions.EqualAddresses, matches, equalAddresses); err != nil {
+		return fmt.Errorf("%w: operation addresses not equal", err)
+	}
+
+	if err := compareOppositeMatches(descriptions.OppositeAmounts, matches, oppositeAmounts); err != nil {
+		return fmt.Errorf("%w: operation amounts not opposite", err)
+	}
+	if err := compareOppositeMatches(descriptions.OppositeOrZeroAmounts, matches, oppositeOrZeroAmounts); err != nil {
+		return fmt.Errorf("%w: both operation amounts not opposite and not zero", err)
+	}
+
+	return nil
+}
+
 // Match contains all *types.Operation matching a given OperationDescription and
 // their parsed *big.Int amounts (if populated).
 type Match struct {


Test patch:
diff --git a/fetcher/fetcher_test.go b/fetcher/fetcher_test.go
index fbf1fec..98e1e63 100644
--- a/fetcher/fetcher_test.go
+++ b/fetcher/fetcher_test.go
@@ -214,31 +214,3 @@ func TestNewWithHTTPCLient(t *testing.T) {
 	var assert = assert.New(t)
 	assert.Same(httpClient, fetcher.rosettaClient.GetConfig().HTTPClient)
 }
-
-func TestNewWithTimeout(t *testing.T) {
-	var assert = assert.New(t)
-
-	fetcher := New("https://serveraddress")
-	assert.Equal(DefaultHTTPTimeout, fetcher.rosettaClient.GetConfig().HTTPClient.Timeout)
-
-	var customTimeout = 6 * time.Minute
-	fetcher2 := New("https://serveraddress", WithTimeout(customTimeout))
-	assert.Equal(customTimeout, fetcher2.rosettaClient.GetConfig().HTTPClient.Timeout)
-
-	// If we pass in a http timeout value when initializing the fetcher, and also pass in an
-	// existing client,
-	// we will simply respect the timeout on the existing client and not override it.
-	var existingClientTimeout = 3 * time.Minute
-	httpClient := &http.Client{
-		Timeout: existingClientTimeout,
-	}
-	apiClient := client.NewAPIClient(
-		client.NewConfiguration(
-			"https://serveraddress",
-			DefaultUserAgent,
-			httpClient,
-		),
-	)
-	fetcher3 := New("https://serveraddress", WithClient(apiClient), WithTimeout(6*time.Minute))
-	assert.Equal(existingClientTimeout, fetcher3.rosettaClient.GetConfig().HTTPClient.Timeout)
-}
diff --git a/parser/match_operations_test.go b/parser/match_operations_test.go
index 5dee9b2..9b25c31 100644
--- a/parser/match_operations_test.go
+++ b/parser/match_operations_test.go
@@ -105,6 +105,152 @@ func TestMatchOperations(t *testing.T) {
 			},
 			err: false,
 		},
+		"simple transfer (with OppositeOrZeroAmounts) and opposite value amounts": {
+			operations: []*types.Operation{
+				{
+					Account: &types.AccountIdentifier{
+						Address: "addr2",
+					},
+					Amount: &types.Amount{
+						Value: "100",
+					},
+				},
+				{}, // extra op ignored
+				{
+					Account: &types.AccountIdentifier{
+						Address: "addr1",
+					},
+					Amount: &types.Amount{
+						Value: "-100",
+					},
+				},
+			},
+			descriptions: &Descriptions{
+				OppositeOrZeroAmounts: [][]int{{0, 1}},
+				OperationDescriptions: []*OperationDescription{
+					{
+						Account: &AccountDescription{
+							Exists: true,
+						},
+						Amount: &AmountDescription{
+							Exists: true,
+							Sign:   NegativeOrZeroAmountSign,
+						},
+					},
+					{
+						Account: &AccountDescription{
+							Exists: true,
+						},
+						Amount: &AmountDescription{
+							Exists: true,
+							Sign:   PositiveOrZeroAmountSign,
+						},
+					},
+				},
+			},
+			matches: []*Match{
+				{
+					Operations: []*types.Operation{
+						{
+							Account: &types.AccountIdentifier{
+								Address: "addr1",
+							},
+							Amount: &types.Amount{
+								Value: "-100",
+							},
+						},
+					},
+					Amounts: []*big.Int{big.NewInt(-100)},
+				},
+				{
+					Operations: []*types.Operation{
+						{
+							Account: &types.AccountIdentifier{
+								Address: "addr2",
+							},
+							Amount: &types.Amount{
+								Value: "100",
+							},
+						},
+					},
+					Amounts: []*big.Int{big.NewInt(100)},
+				},
+			},
+			err: false,
+		},
+		"simple transfer (with OppositeOrZeroAmounts) and 0-value amounts": {
+			operations: []*types.Operation{
+				{
+					Account: &types.AccountIdentifier{
+						Address: "addr2",
+					},
+					Amount: &types.Amount{
+						Value: "0",
+					},
+				},
+				{}, // extra op ignored
+				{
+					Account: &types.AccountIdentifier{
+						Address: "addr1",
+					},
+					Amount: &types.Amount{
+						Value: "0",
+					},
+				},
+			},
+			descriptions: &Descriptions{
+				OppositeOrZeroAmounts: [][]int{{0, 1}},
+				OperationDescriptions: []*OperationDescription{
+					{
+						Account: &AccountDescription{
+							Exists: true,
+						},
+						Amount: &AmountDescription{
+							Exists: true,
+							Sign:   AnyAmountSign,
+						},
+					},
+					{
+						Account: &AccountDescription{
+							Exists: true,
+						},
+						Amount: &AmountDescription{
+							Exists: true,
+							Sign:   AnyAmountSign,
+						},
+					},
+				},
+			},
+			matches: []*Match{
+				{
+					Operations: []*types.Operation{
+						{
+							Account: &types.AccountIdentifier{
+								Address: "addr2",
+							},
+							Amount: &types.Amount{
+								Value: "0",
+							},
+						},
+					},
+					Amounts: []*big.Int{big.NewInt(0)},
+				},
+				{
+					Operations: []*types.Operation{
+						{
+							Account: &types.AccountIdentifier{
+								Address: "addr1",
+							},
+							Amount: &types.Amount{
+								Value: "0",
+							},
+						},
+					},
+					Amounts: []*big.Int{big.NewInt(0)},
+				},
+			},
+			err: false,
+		},
 		"simple transfer (with too many opposite amounts)": {
 			operations: []*types.Operation{
 				{