From 8d3b266bf22d3e1f7f653be28d10ddc0cce02475 Mon Sep 17 00:00:00 2001
From: Eric Rutherford <eric@invisionapp.com>
Date: Mon, 8 Mar 2021 22:44:37 -0600
Subject: [PATCH] adding a custom assertor function signature that implements
 the Assertor interface

---
 .travis.yml        |  4 +++-
 README.md          |  7 ++++---
 assertions.go      | 19 ++++++++++++++++++
 assertions_test.go | 50 ++++++++++++++++++++++++++++++++++++++++++++++
 4 files changed, 76 insertions(+), 4 deletions(-)

diff --git a/.travis.yml b/.travis.yml
index 46893a6..f3b525b 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,8 +1,10 @@
 language: go
 
 go:
-  - 1.12.x
   - 1.13.x
+  - 1.14.x
+  - 1.15.x
+  - 1.16.x
   - master
 
 script:
diff --git a/README.md b/README.md
index 9fd5ef8..186ce12 100644
--- a/README.md
+++ b/README.md
@@ -45,13 +45,14 @@ supported assertions are:
 * The expected body of your request
 
 [WithTesting](https://godoc.org/github.com/maxcnunes/httpfake#WithTesting) **must** be provided as a server
-option when creating the test server if intend to set request assertions. Failing to set the option
+option when creating the test server if you intend to set request assertions. Failing to set the option
 when using request assertions will result in a panic.
 
 ### Custom Assertions
 
-You can also provide your own request assertions by creating a type that implements the
-[Assertor interface](https://godoc.org/github.com/maxcnunes/httpfake#Assertor). The `Assertor.Log` method will be
+You can also provide your own assertions by creating a type that implements the
+[Assertor interface](https://godoc.org/github.com/maxcnunes/httpfake#Assertor) or utilizing the
+[CustomAssertor function type](https://pkg.go.dev/github.com/maxcnunes/httpfake#CustomAssertor). The `Assertor.Log` method will be
 called for each assertion before it's processed. The `Assertor.Error` method will only be called if the
 `Assertor.Assert` method returns an error.
 
diff --git a/assertions.go b/assertions.go
index 2a9bf90..907b68d 100644
--- a/assertions.go
+++ b/assertions.go
@@ -168,3 +168,22 @@ func (b *requiredBody) Log(t testing.TB) {
 func (b *requiredBody) Error(t testing.TB, err error) {
 	t.Errorf(assertErrorTemplate, err)
 }
+
+// CustomAssertor provides a function signature that implements the Assertor interface. This allows for
+// adhoc creation of a custom assertion for use with the AssertCustom assertor.
+type CustomAssertor func(r *http.Request) error
+
+// Assert runs the CustomAssertor assertion against the provided request
+func (c CustomAssertor) Assert(r *http.Request) error {
+	return c(r)
+}
+
+// Log prints a testing info log for the CustomAssertor
+func (c CustomAssertor) Log(t testing.TB) {
+	t.Log("Testing request with a custom assertor")
+}
+
+// Error prints a testing error for the CustomAssertor
+func (c CustomAssertor) Error(t testing.TB, err error) {
+	t.Errorf(assertErrorTemplate, err)
+}
diff --git a/assertions_test.go b/assertions_test.go
index 89472cd..47ae931 100644
--- a/assertions_test.go
+++ b/assertions_test.go
@@ -266,6 +266,36 @@ func TestAssertors_Assert(t *testing.T) {
 			},
 			expectedErr: "error reading the request body; the request body is nil",
 		},
+		{
+			name: "CustomAssertor should execute the custom assertor as expected",
+			assertor: CustomAssertor(func(r *http.Request) error {
+				return nil
+			}),
+			requestBuilder: func() (*http.Request, error) {
+				testReq, err := http.NewRequest(http.MethodGet, "http://fake.url", nil)
+				if err != nil {
+					return nil, err
+				}
+
+				return testReq, nil
+			},
+			expectedErr: "",
+		},
+		{
+			name: "CustomAssertor should execute the custom assertor and return an error as expected",
+			assertor: CustomAssertor(func(r *http.Request) error {
+				return errors.New("custom assertor error")
+			}),
+			requestBuilder: func() (*http.Request, error) {
+				testReq, err := http.NewRequest(http.MethodGet, "http://fake.url", nil)
+				if err != nil {
+					return nil, err
+				}
+
+				return testReq, nil
+			},
+			expectedErr: "custom assertor error",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -341,6 +371,16 @@ func TestAssertors_Log(t *testing.T) {
 			assertor: &requiredBody{},
 			expected: "Testing request for a required body value\n",
 		},
+		{
+			name: "CustomAssertor Log should log the expected output when called",
+			mockTester: &mockTester{
+				buf: &bytes.Buffer{},
+			},
+			assertor: CustomAssertor(func(r *http.Request) error {
+				return nil
+			}),
+			expected: "Testing request with a custom assertor\n",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
@@ -401,6 +441,16 @@ func TestAssertors_Error(t *testing.T) {
 			assertor: &requiredBody{},
 			expected: "assertion error: test error",
 		},
+		{
+			name: "CustomAssertor Log should log the expected output when called",
+			mockTester: &mockTester{
+				buf: &bytes.Buffer{},
+			},
+			assertor: CustomAssertor(func(r *http.Request) error {
+				return nil
+			}),
+			expected: "assertion error: test error",
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {