feat(numbers): added InEpsilonSymmetric (#109)

This variant of InEpsilon (also available as a generic assertion),
uses a modified relative error, so that both operands play a symmetric
role.

This is useful when the "expected" value doesn't play a particular role
when asserting that 2 numbers are close. Mirrors python's math.isclose.

Refers to: stretchr#1839

Signed-off-by: Frederic BIDON <fredbi@yahoo.com>

Author: fredbi

.gitignore

@@ -4,3 +4,4 @@ Godeps
 .idea
 *.out
 .mcp.json
+go.work.sum

assert/assert_assertions.go

@@ -40,7 +40,7 @@ Each domain contains assertions regrouped by their use case (e.g. http, json, er
 - [File](./file.md) - Asserting OS Files (6)
 - [Http](./http.md) - Asserting HTTP Response And Body (7)
 - [Json](./json.md) - Asserting JSON Documents (5)
-- [Number](./number.md) - Asserting Numbers (7)
+- [Number](./number.md) - Asserting Numbers (9)
 - [Ordering](./ordering.md) - Asserting How Collections Are Ordered (10)
 - [Panic](./panic.md) - Asserting A Panic Behavior (4)
 - [Safety](./safety.md) - Checks Against Leaked Resources (Goroutines, File Descriptors) (2)

assert/assert_assertions_test.go

@@ -15,14 +15,14 @@ Counts for core functionality, and generated variants (formatted, forward, forwa
 
 | Kind                      | Count             | Note |
 | ------------------------- | ----------------- | ---- |
-| All core functions             | 135 | Maintained core |
-| All core assertions       | 131 | Usage with `*testing.T` |
-| Generic assertions        | 50   | Type-safe assertions ("T" suffix) |
+| All core functions             | 137 | Maintained core |
+| All core assertions       | 133 | Usage with `*testing.T` |
+| Generic assertions        | 51   | Type-safe assertions ("T" suffix) |
 | Helpers (not assertions)  | 4    | General-purpose utilities, not assertions |
 | Others                    | 0     | |
-| assert/require variants   | 424 | Generated variants |
-| Total assertions variants | 848 | Available assertions API |
-| Total API surface         | 858 | |
+| assert/require variants   | 430 | Generated variants |
+| Total assertions variants | 860 | Available assertions API |
+| Total API surface         | 870 | |
 
 ## Quick index
 
@@ -71,6 +71,8 @@ Table of core assertions, excluding variants. Each function is side by side with
 | [InDeltaT[Number Measurable]](number/#indeltatnumber-measurable) {{% icon icon="star" color=orange %}} |  | number |  |
 | [InEpsilon](number/#inepsilon) |  | number |  |
 | [InEpsilonSlice](number/#inepsilonslice) |  | number |  |
+| [InEpsilonSymmetric](number/#inepsilonsymmetric) |  | number |  |
+| [InEpsilonSymmetricT[Number Measurable]](number/#inepsilonsymmetrictnumber-measurable) {{% icon icon="star" color=orange %}} |  | number |  |
 | [InEpsilonT[Number Measurable]](number/#inepsilontnumber-measurable) {{% icon icon="star" color=orange %}} |  | number |  |
 | [IsDecreasing](ordering/#isdecreasing) | [IsNonDecreasing](ordering/#isnondecreasing) | ordering |  |
 | [IsDecreasingT[OrderedSlice ~[]E, E Ordered]](ordering/#isdecreasingtorderedslice-e-e-ordered) {{% icon icon="star" color=orange %}} | [IsNonDecreasingT](ordering/#isnondecreasingtorderedslice-e-e-ordered) | ordering |  |