Add IgnoringNewLines string decorator

README.md

@@ -90,7 +90,7 @@ For the following types basic assertions are supported
     * [x] HasSizeLessThan
     * [x] HasSizeLessThanOrEqualTo
     * [x] IsEqualToIgnoringCase
-    * [ ] IsEqualToIgnoringNewLines
+    * [x] IsEqualToIgnoringNewLines
     * [x] IsEqualToIgnoringWhitespace
     * [x] IsLowerCase
     * [x] IsNotEqualToIgnoringCase

assert/string.go

@@ -30,6 +30,13 @@ func IgnoringWhiteSpaces() StringOpt {
 	}
 }
 
+// IgnoringNewLines removes the new lines from the value under assertion.
+func IgnoringNewLines() StringOpt {
+	return func(c *AssertableString) {
+		c.actual = c.actual.AddDecorator(values.RemoveNewLines)
+	}
+}
+
 // ThatString returns an AssertableString structure initialized with the test reference and the actual value to assert.
 func ThatString(t *testing.T, actual string, opts ...StringOpt) AssertableString {
 	t.Helper()

assert/string_test.go

@@ -63,7 +63,7 @@ func TestAssertableString_IsEqualTo(t *testing.T) {
 		actual     string
 		expected   string
 		shouldFail bool
-		StringOpt
+		stringOpts []StringOpt
 	}{
 		{
 			name:       "should assert not equal strings",
@@ -82,13 +82,22 @@ func TestAssertableString_IsEqualTo(t *testing.T) {
 			actual:     "somestring with white spaces",
 			expected:   "some stringwith white spaces",
 			shouldFail: false,
-			StringOpt:  IgnoringWhiteSpaces(),
+			stringOpts: []StringOpt{IgnoringWhiteSpaces()},
+		},
+		{
+			name: "should assert equal strings ignoring new lines",
+			actual: `some string 
+with white spaces`,
+			expected: `some string with 
+white spaces`,
+			shouldFail: false,
+			stringOpts: []StringOpt{IgnoringNewLines()},
 		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {
 			test := &testing.T{}
-			ThatString(test, tt.actual, tt.StringOpt).IsEqualTo(tt.expected)
+			ThatString(test, tt.actual, tt.stringOpts...).IsEqualTo(tt.expected)
 			ThatBool(t, test.Failed()).IsEqualTo(tt.shouldFail)
 		})
 	}

internal/pkg/values/string_value.go

@@ -20,6 +20,12 @@ func RemoveSpaces(value string) string {
 	return strings.ReplaceAll(value, " ", "")
 }
 
+// RemoveNewLines removes all new lines from the given string.
+func RemoveNewLines(value string) string {
+	value = strings.ReplaceAll(value, "\r\n", "")
+	return strings.ReplaceAll(value, "\n", "")
+}
+
 // IsEqualTo returns true if the value is equal to the expected value, else false.
 func (s StringValue) IsEqualTo(expected interface{}) bool {
 	return s.DecoratedValue() == s.decoratedValue(expected)