Implement string_to_not_be_blank assertion

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- Added `expect/string_to_not_be_blank` for asserting that a string is neither empty nor consists only of whitespace characters.
+
 ## [0.5.0] - 2024-07-31
 
 ### Added

birdie_snapshots/expect_string_to_not_be_blank_given_empty_string.accepted

@@ -0,0 +1,11 @@
+---
+version: 1.1.5
+title: expect/string_to_not_be_blank given empty string
+---
+Expected "" to not be blank
+
+- Expected
++ Received
+
+- non-empty or non-whitespace-only string
++ ""

birdie_snapshots/expect_string_to_not_be_blank_given_whitespace_only_string.accepted

@@ -0,0 +1,11 @@
+---
+version: 1.1.5
+title: expect/string_to_not_be_blank given whitespace-only string
+---
+Expected "\t \n " to not be blank
+
+- Expected
++ Received
+
+- non-empty or non-whitespace-only string
++ "\t \n "

src/startest/expect.gleam

@@ -113,6 +113,20 @@ pub fn to_be_none(actual: Option(a)) -> Nil {
   }
 }
 
+/// Asserts that the given string is neither empty nor consists only of whitespace characters.
+pub fn string_to_not_be_blank(actual: String) -> Nil {
+  case actual |> string.trim() |> string.is_empty() {
+    False -> Nil
+    True ->
+      AssertionError(
+        string.concat(["Expected ", string.inspect(actual), " to not be blank"]),
+        string.inspect(actual),
+        "non-empty or non-whitespace-only string",
+      )
+      |> assertion_error.raise
+  }
+}
+
 /// Asserts that the given string contains the expected string.
 pub fn string_to_contain(actual: String, expected: String) -> Nil {
   case string.contains(does: actual, contain: expected) {

test/startest/expect_test.gleam

@@ -161,6 +161,28 @@ pub fn to_be_none_tests() {
   ])
 }
 
+pub fn string_to_not_be_blank_tests() {
+  describe("startest/expect", [
+    describe("string_to_not_be_blank", [
+      describe("given a string that is neither empty nor whitespace-only", [
+        it_passes(fn() { expect.string_to_not_be_blank("Gunter") }),
+      ]),
+      describe("given a string that is empty", [
+        it_fails_matching_snapshot(
+          "expect/string_to_not_be_blank given empty string",
+          fn() { expect.string_to_not_be_blank("") },
+        ),
+      ]),
+      describe("given a string that consists only of whitespace characters", [
+        it_fails_matching_snapshot(
+          "expect/string_to_not_be_blank given whitespace-only string",
+          fn() { expect.string_to_not_be_blank("\t \n ") },
+        ),
+      ]),
+    ]),
+  ])
+}
+
 pub fn string_to_contain_tests() {
   describe("startest/expect", [
     describe("string_to_contain", [