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+# Table-Driven Testing with hydronica/trial
+
+The `hydronica/trial` package makes table-driven testing in Go simple and expressive. Below are practical examples and patterns for using this library, including time helper functions. For more, see the [trial wiki](https://github.com/hydronica/trial/wiki).
+
+---
+
+## Principles 
+1. Keep it simple
+   1. Use primitives when possible for input and output. 
+   2. Functions with multiple args can be passed in by creating an input struct with each arg
+2. Return errors in the test function. Use nil if needed  
+3. Test cases should be self-contained
+4. limit scope of custom structs and helper function by embedding them without the Test Function
+
+## 
+
+```go
+import (
+    "testing"
+    "github.com/hydronica/trial"
+)
+
+func Add(i1, i2 int) int {
+    return i1 + i2
+}
+
+func TestAdd(t *testing.T) {
+    type input struct {
+        i1 int 
+        i2 int
+    }
+    testFn := func(in input) (int, error) {
+        return Add(in.i1, in.i2), nil
+    }
+    cases := trial.Cases[input, int]{
+        "Add two numbers": {
+            Input:    input{i1:1, i2:2},
+            Expected: 3,
+        },
+    }
+    trial.New(testFn, cases).Test(t)
+}
+```
+
+---
+
+## Testing with error and using output struct
+
+```go
+import (
+    "encoding/json"
+    "errors"
+    "testing"
+    "github.com/hydronica/trial"
+)
+
+type output struct {
+    Name  string
+    Count int
+    Value float64
+}
+
+func TestMarshal(t *testing.T) {
+    fn := func(s string) (output, error) {
+        v := output{}
+        err := json.Unmarshal([]byte(s), &v)
+        return v, err
+    }
+    cases := trial.Cases[string, output]{
+        "valid": {
+            Input:    `{"Name":"abc", "Count":10, "Value": 12.34}`,
+            Expected: output{Name: "abc", Count: 10, Value: 12.34},
+        },
+        "invalid type": {
+            Input:       `{"Value", "abc"}`,
+            ExpectedErr: errors.New("invalid character"),
+        },
+        "invalid json": {
+            Input:     `{`,
+            ShouldErr: true,
+        },
+    }
+    trial.New(fn, cases).SubTest(t)
+}
+```
+
+---
+
+## Using Time Helper Functions
+
+The package provides helpers for time parsing in tests:
+- `TimeHour(s string)` — format: `"2006-01-02T15"`
+- `TimeDay(s string)` — format: `"2006-01-02"`
+- `Time(layout, value string)`
+- `Times(layout string, values ...string)`
+- `TimeP(layout, s string) *time.Time`
+
+## Using Pointer Helper Functions
+
+The `Pointer[T]` helper function makes it easy to create pointers to primitive values in your test cases. This is particularly useful when testing functions that expect pointer parameters.
+
+Supported primitive types:
+- Integers: `int`, `int8`, `int16`, `int32`, `int64`
+- Unsigned integers: `uint`, `uint8`, `uint16`, `uint32`, `uint64`
+- Floats: `float32`, `float64`
+- `string`
+- `bool`
+
+
+---
+
+## Using Custom Comparers
+
+You can customize how trial compares expected and actual values using comparers. For example, you may want to ignore unexported fields or certain struct fields when comparing results.
+
+```go
+import (
+    "testing"
+    "time"
+    "github.com/hydronica/trial"
+)
+
+type Example struct {
+    Field1     int
+    Field2     int
+    ignoreMe   string    // unexported, will be ignored
+    Timestamp  time.Time // will be ignored
+    LastUpdate time.Time // will be ignored
+}
+
+func TestWithComparer(t *testing.T) {
+    fn := func(i int) (Example, error) {
+        return Example{
+            Field1: i,
+            Field2: i * 2,
+            ignoreMe: "should be ignored",
+            Timestamp: time.Now(),
+            LastUpdate: time.Now(),
+        }, nil
+    }
+    cases := trial.Cases[int, Example]{
+        "basic": {
+            Input:    2,
+            Expected: Example{Field1: 2, Field2: 4},
+        },
+    }
+    trial.New(fn, cases).Comparer(
+        trial.EqualOpt(
+            trial.IgnoreAllUnexported,
+            trial.IgnoreFields("Timestamp", "LastUpdate"),
+        ),
+    ).SubTest(t)
+}
+```
+
+This will compare only the exported fields `Field1` and `Field2`, ignoring the unexported and specified fields.
+
+---